130 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBore scoring
Reported or suspected cause
less durable, especially
Reported cause
No successful repair reported for this finding.
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Identified cause
0
Suspected cause
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Reported fixes
Read evidence and context
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Reported cause
Also, when the 3.6 was intro'd they changed to a more "efficient" Lokasil process that turned out to be less durable, especially with the higher con-rod angles against the bore.
Leading evidence: 'less durable, especially' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'less durable, especially' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Adjust behavior i mean proper oil' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed
Because the flywheel speed sensor reads the speed every 3 power strokes any imbalance can only be adjusted by the ECU on the third stroke and as cylinder 4 is next and the bank 2 cam chain on the end of the IMS shaft feels any adjustment next, that chain receives the biggest jerk.
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Performed · outcome unconfirmed
A few decades ago - when tickover was adjusted by a screw - you raised it until any “ticking stopped” (hence the term tickover).
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Performed · outcome unconfirmed
I have removed the engine for IMBS update and of course have the UAOS/UIDS installed on it..But I use quality oil and monitor everything closely and take care of anything that can shorten the life of it ..
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Performed · outcome unconfirmed
I didn't hesitate to have the solution installed within days of getting my car.
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Performed · outcome unconfirmed
Because the flywheel speed sensor reads the speed every 3 power strokes any imbalance can only be adjusted by the ECU on the third stroke and as cylinder 4 is next and the bank 2 cam chain on the end of the IMS shaft feels any adjustment next, that chain receives the biggest jerk.
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Suggestion
If it is a tiptronic and at tickover the noise goes away or reduces if you engage “D” or if you switch on the air-con and it goes away or reduces and your tail pipes are equally sooty - you probably do not have a serious problem (boroscope to check).
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
less durable, especially
No successful repair reported for this finding.
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Identified cause
0
Suspected cause
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Reported fixes
Read evidence and context
Discussions that report identifying a cause
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
Also, when the 3.6 was intro'd they changed to a more "efficient" Lokasil process that turned out to be less durable, especially with the higher con-rod angles against the bore.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
130 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
2 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
Sometimes a sticky tappet is the cause but it is expensive to change them and find it made no difference.
Seems like everywhere I read most if not all 996/997 cars will have some kind of bore scoring. Is that a safe assumption? I want to buy one but not fond of the fact that most will have issues? Thoughts?
You need to read some more. That statement is overly generalized. My 99 C2 (produced 7/98) has 148K glorious miles and still running strong. I really enjoy my ownership.
Not if the previous owners ran good oil and changed it a couple of times a year. Definitely buy a 996. Just make sure you get one with service records to see and prove what was performed and when, as well as scope the bores. Owned mine for 20 years and would buy it all over again.
997 3.8 I would say yeah, pretty much a case of when not if, however, many will see signs of it and then do another 75k miles before it becomes a real issue.
997 3.6 seems to suffer more than the 996 3.6, which doesn't suffer much at all.
996 3.4 it is incredibly rare.
Porsche recomended oil and filter changes every 20k for the 997. 15k for the 996. Kinda silly isn't it.
Seems that we got alot of worn out and dirty old oil...
This is what I figured during my research. And, if you want to carry it down through the Boxster displacements: 2.5L and 2.7L pretty much never, 3.2L maybe a few cases. Also, when the 3.6 was intro'd they changed to a more "efficient" Lokasil process that turned out to be less durable, especially with the higher con-rod angles against the bore.
20k! That's just crazy, asking for trouble. I change my oil once a year around 4k miles but check and change the filter mid-way through this interval. Plus, I'm in a warm climate and never drive less than 30 miles.
Well, a couple of thoughts and my opinion. First of all - engine is a mechanical device so it means that once you start to use that it will start to wear from the day one.
Seems that most if not all engines/motors have some kind of a mechanical achilles heel ie. if nothing else it will eventually brake because of that and that because of the mechanical design.
On BMW early N47 engines that is the timing chain which is supposed to last a lifetime and because of that those smart engineers at BMW located that chain to the back of the engine - in other words between the firewall and the engine so changing that is a challenge that typically requires dropping the engine or at least the transmission. The problem of that timing chain is of course that it stretches over time and eventually will cause a timing issue and blown engine.
Well that issue on 996/997 is the bore scoring. If nothing else brakes it'll eventually suffer from bore scoring - sooner or later every 996/997 will suffer from bore scoring if nothing else or done some preventive action like rebuild the cylinders with Nikasil even before the bore scoring occurs. Problem with that is of course the price - it'll cost +-10k even if you rebuild the engine yourself. Of course as there are some known things that contributes to the scoring avoiding those can postpone this occurance further (ie. proper maintenance and taking care of the car in general).
996 that has never seen cold climate, has had oil changed every 5k / 6 months through out the 20 year history, has been driven properly long distances (no 1 mile daily driver) there's a random gem that will last forever - but unfortunately that's not the case of majority of 996/997s.
In a perfect world there would be an option to buy crankcase halfs off the self with the cylinder structure of the use case. Unfortunately we are too early - some day in the future technology would enable us to 3D print that then install the sleeve/plating/coating but by that time I think we are will be driving EVs.
It would be good if Porsche would step up and offer a 997 (3.8L) short block programs for $9K like the 996 programs. That would go a long way in solving this problem and restore faith to the faithful. I might even buy Porsche stock after the IPO.
I think you guys are making more out of bore scoring than you need to. Sure, if you didn't change your oil or the previous owners didn't change the oil, then you may have a problem.
Easiest thing to do is test your oil and take it into your Porsche indy and get your bores scoped. You either have it or you dont. If you do, you are better off knowing so you can slow down its growth with the proper measures. If you don't, then make sure you run good oil and change it at least 2x a year so you don't get it.
Remember, the engine is 20 years old. There is not an engine in any car on any planet that lasts forever. They all will need a rebuild. Just a fact of physical science.
I love the comment above with bore scoring being the new IMSB hype.
IMSB failure is essentially non-existent and rare. Bore scoring seems to be the same. I found a very thorough and detailed write-up of 3.4L idle tick on the 911 UK forum. I have noticed my idle tick vanishes completely if I turn on A/C... Because my compressor doesn't kick on (because I have a cracked A/C condenser that leaks all freon/compressor oil), the idle jumps to around 900rpm and the ticking goes away - oil pressure also jumps to 1.5-2 bar. My understanding is that idle is supposed to decrease with compressor on, but I may have that backward - my compressor doesn't turn on as just mentioned. It is an easy fix I have used to prevent the "tick" - as I've said many times before, there is no other symptom I have of bore scoring - no, I have no scoped the cylinders. There is another guy on the 911 UK forum that describes using air con as workaround as well.
I'll paste the comment here:
- - - -
"996 ticking noises can be signs of a problem or just a feature of the engine and its management system. If it has a tick after a rebuild it is almost certainly nothing to be concerned about.
If it is a tiptronic and at tickover the noise goes away or reduces if you engage “D” or if you switch on the air-con and it goes away or reduces and your tail pipes are equally sooty - you probably do not have a serious problem (boroscope to check).
The model has several reasons for a tick and several cures and sometimes it cannot be cured. It is usually from the bank 2 area half way from the crank to the camshaft, back of engine cylinder 4 area.
All engines speed up and slow down between each firing stroke and this causes a shake to the various chains, cams and tensioners. This engine has more chains than later ones.
A few decades ago - when tickover was adjusted by a screw - you raised it until any “ticking stopped” (hence the term tickover). An engine would then normally speed up at tickover when the oil is hotter and thinner but to reduce emissions (checked at tickover) and fix that problem more modern cars are made so the management system makes the tickover speed drop as the engine warms up (to compensate).
But older engines that are very free running and with lower oil pressure, weaker leaking tappets and cam timing systems - can lower the revs too far for an older engine when hot (especially if you leave it running to listen for a tick as heat soak initially raises oil temperatures and lowers viscosity even further).
Tickover revs can be increased when re-mapping – there are 8 or 10 settings at different temperatures gradually reducing the tickover revs as things warm up and ambient conditions affect the engine – sometimes raising these individual settings sorts the problem although the slightly higher tickover can change the drivers familiarity with the right throttle position for smooth driving off in first gear and can take a while to get used to and it is not an easy job (as the engine is sitting ticking over and changing various temperatures while the operative is trying to find the setting that reduces or fixes the issue) and it is not free either.
The main chain tensioners are a very poor design indeed. No reservoirs and not even a sprung loaded ball non-return valve. Furthermore the feed is after all the other drains on oil pressure and flow to the tappets, variocam systems, camshaft bearing areas etc. The tensioner has a tiny flat plate that is supposed to seal the return stroke if the chains flap.
The bank 1 tensioner allows the tiny sealing plate to fall onto the sealing face so when you strip it you usually find it full of oil still and with some resistance. The bank 2 one is upside down (so the sealing plate is always unsealed unless there is good oil pressure available) and is always empty when you strip it and has no resistance at all. There is not even a seal on the piston. This shows that at relatively low oil pressure and delivery this tensioner probably does nothing much to stabilise the cam chain ******.
The oil that feeds the tensioner is delivered to the head via a gallery that also feeds the tappets, variable cam timing unit (that also incorporates a tensioner) and the camshaft bearing journals. The oil pump design is poor on oil delivery at low revs and it is entirely possible that minute wear everywhere results in the oil being pumped into the head barely filling these components and by the time the oil in the gallery reaches the main chain tensioner from the IMS it just shunts back and forth in the gallery and fails to make the tensioner do its job.
We have over the years gone through changing just about everything you could think of to eliminate the noises. This includes heads, tappets, tappet housings, injectors, chains sprockets, tensioners, cams, pistons etc. Sometimes a sticky tappet is the cause but it is expensive to change them and find it made no difference. We even tried making tensioners with different springs and a ball valve which sometimes worked but often didn’t and finally concluded that at tickover the tensioner piston just flaps back and forth and the oil flow from the head isn’t sufficient to keep it pressured but just experiences the movement of the tensioner creating a pressure wave in the oil feed gallery leading to it but insufficient oil flow to maintain the tensioner blade position– hence the tick.
Because there are three firing stokes/engine rev – anything that causes one cylinder to produce a slightly different push on the piston (like a sticky injector) can result in the management system reading a pulse that it over corrects for setting up a cyclic speeding up and down of the tickover revs that also encourages ticking noises.
Rebuilding an engine can make it worse because the original standard cylinders had quite variable piston clearances and bore shapes and produce less tickover compression and therefore less of a tickover pulse from each power stroke than a rebuilt engine with tighter more powerful piston clearances and overhauled cylinder heads etc – that it was not designed to manage.
Different exhaust systems can also work better at higher revs than at tickover leading to rougher tickover performance - again moving the control parameters away from their designed areas – so really any uneven running between cylinders makes things worse and rebuilds with better than standard compression or bigger pistons can create a slight tickover problem (especially with lighter flywheels).
We only find this problem with the 996 3.4 engines and they also have off-set gudgeon pin alignment that works out different for one bank of the engine than the other (which doesn’t help). The Cayman S, 3.6 and 3.8 engines put that right but I guess it was found not to be an issue because the Gen 2 has gone back again to the original variance in off-set between banks.
Other reasons already previously listed by other contributors are probably all valid since almost anything can influence the tickover running between individual cylinders and it is therefore always possible to find someone who found a solution to their problem that they are trying to help by revealing – but that turned out didn’t work for anyone else.
Because the flywheel speed sensor reads the speed every 3 power strokes any imbalance can only be adjusted by the ECU on the third stroke and as cylinder 4 is next and the bank 2 cam chain on the end of the IMS shaft feels any adjustment next, that chain receives the biggest jerk.
Having spent hours and hours (and a not inconsiderable amount of money) trying to eliminate this problem - unless you have other problems or signs of imminent failure – it is probably just a noise that many have wasted hours trying to fix and usually eventually give up on after absolutely everything has been changed and the tick is still there.
You could get lucky and identify and change the component causing your problem first time but the odds are very much against it and you would be more likely to spend time and money getting frustrated and more annoyed with the engine and whoever you paid to try and fix it –all to no avail – as more often than not it is better just to live with it.
If the noise is not in the area I have descibed above it may be worthwhile investigating further but if it fits the descriptions most people provide and there is nothing else wrong with the car I suggest it is best to ignore it.
Sorry there is not an easy answer.
Baz"
What a long winded bunch of BS... Imagine trying to tell a customer who just paid $80k for a new 996 that his noise couldn't be cured, just to live with it...lol
Also not only is the 3.4 piston pin off-set, but the I know for sure and it documented here that 3.6 996 has the same piston pin off-set..
and don't kid yourself that IMSB failure is not an issue, lol, or borescoring either...hell IMSB even has it's own Facebook page with huge following...lol
2005(996)/C4S.
Classic symptoms that all started minimal and
progressed over five years(2014-2019) to severe especially the ticking
.
Occasional puff of smoke on start up, sooty left side tailpipe(I thought what the heck it's a tailpipe after all), Some spitting on garage floor after first start of the day(I figured moisture/carbon from humidity), slow increase in oil consumption, faint ticking from bank two side that became pronounced by year five. The pic is my cylinder six. Cylinder five was just behind it in severity. Cylinder four was starting the same.
My guess is previous owners followed the owners manual on oil changes as GC996 suggests above.
Scoring is NOT hype...
If I'm not mistaken, that article was written by Baz of Hartech fame. They are a well known UK Porsche engine specialist:
https://www.hartech.org/
I am not here to argue his reasoning is legit or BS, but knowing their history I would expect his knowledge base to be high. It's possible his post is being taken out of context and erroneously applied to a different issue. Baz is well versed in bore scoring & IMSB issues, they rebuild engines daily for these types of failures. His thoughts are likely directed at ticking complaints where bore scoring has already been eliminated as the cause.
This forum actually has a decent amount of "Feel Good" threads now and then, however, the forum is not where most people come to wax poetic. If you're "reading a lot of problems" it's probably a symptom of reading the trouble forums. If you gathered your data by attending PCA meets and talking to current owners you'd probably already own one by now.
The fact of the matter is that the 996 M96 doesn't have "unusual noises" that cannot be cured...
I know who Baz is and just got tired of reading.....and this comment I found at the top set the stage..".
If it has a tick after a rebuild it is almost certainly nothing to be concerned about "
Yes right...lol
I�m not asking what the signs are. I�m asking what other symptoms (edit- signs) he had.
so now we�re using social media as credibility.
I don�t know what I�m talking about, but I�m convinced 95% of you don�t either.
I�ve said many times that a tick at idle with no other symptoms is probably not bore scoring, and something else. That�s why I asked what else that guy was experiencing.
You know the routine, when you are a newbie, you should trust nothing and verify. Because you dont know if the info you are getting is good or bad.
When you have been around the block for 20 years, you already know the issues, what solutions actually make sense, and which ones work.
The challenge is the newbies will question as they should and the seasoned vets will keep giving the same answers. Eventually the newbies get enough information to verify and enough knowledge and experience to apply the info properly.
But to your point, sure, there are alot of folks that really have no idea.
Cool - so it seems like it took more or less 5 years, without doing anything different than previous owners, to get to the state you found yourself in where a rebuild was the only way to go. The reason I asked, for all those that have posted photos with fear of bore scoring (even though they're streaks at best) and thinking they need an immediate rebuild, it would appear that as long as you adjust your behavior now, you easily could have more than 5 years of driving you could potentially do while you figure out future steps and save up some coin. By adjusting your behavior I mean proper oil changes / interval and a low temp thermostat at the very least. From there just track metals with a UOA. You can't undo what's been done but you can certainly manage it for quite some time. Often what's been done isn't as bad as the internet may have you believe. Fear has big eyes.
One thing you didn't ask was: "Did you continue to drive the car as the signs/symptoms grew?"
Answer: "No I did not. The paranoia from worrying about what certainly exhibited all the signs/symptoms(which ever) of bore scoring led me not enjoy driving the car and it became a garage queen."
When it threw a misfire code for cylinder 6 and I found a bridged spark plug I scoped the car and found what required a reconstruction of the engine.
Best car decision I've ever made.
Sure, I hear you and I presume you stopped driving the car in 2019? "Classic symptoms that all started minimal andprogressed over five years(2014-2019) to severe especially the ticking" would indicate you still drove it over that period. If you didn't drive the car for 5 years the symptoms would not have progressed. I'm just trying to make a distinction between "something doesn't seem right but I'll continue to drive the car without any changes to what I've been doing" VS "something doesn't seem right - I'll make some changes to my maintenance and continue to drive while monitoring the situation. Nothing wrong with either but with all the information that's available now if someone finds early signs of scoring and makes appropriate adjustments they have a very good chance of being able to drive the car for many years before getting invasive. Charles Navarro said himself that one of the worst things you can do is stop driving the car. Of course, if you're at the end of the road, like you were after 5 years, then the maintenance ship has sailed.
I did drive the car from 2014 to 2019 just at a very low mileage per year rate.
In 2019 the car was sent for repair.
The information that is available now was not available or perhaps I was just not aware as I went through the progression of symptoms. So, yes, there are ways to mitigate/live with the issue today.
I had my car (2003) scoped in 2018 as part of the PPI @ 45000 miles. No visible scoring. I've only driven the car 4000 miles. Throughout my ownership, sometimes at startup I hear a minor tick (I open the window to always listen). Lasts a couple of minutes. Most times there is no tick. If the car is driven in back to back days, I don't ever hear a tick.
I think (hope) that it is not bore scoring. I have never heard the tick when warm, after a short drive (<10 miles) or extended drives. There is no tail pipe soot differences.
I change oil yearly in November. Car is driven on that day for the final drive of the season and is parked until end of March/early April. Car is never started during storage. Car is never driven in temps below 40 degrees.
So, my infrequent tick I hope is due to oil drain out of lifters or tensioners. Tick cannot be heard inside the car. I have no plans to scope the car again unless there is a reason to luck a regular tick or additional soot.
I use 5w40 - Castrol Edge. No plans on using DT40 due to cost in Canada.
I had the Solution installed at 45K and so I don't use the cartridge filter.
I don't hammer the car until warm. I never take the car out for anything less than a 20 minute drive. I don't even back it out of the driveway to wash without warming it up with a drive.
I've had a new waterpump, thermostat installed. Also AOS.
Hopefully I dodge the bore scoring dilemma and haven't jinxed myself.
I often wonder if my tick is just the tensioners or lifters pressuring up with oil....
my 3/98 had a thick noise. Everyone said bore scoring, heck some people we�re already saying FSI rebuild. Anyway, porsche tech 3 said probably carbon deposits on piston tops. Yeah CRC GDI thru throttle tick is gone. Also now I run a mix of Mobil 1
0w40, with 5W50. Better oil pressure at idle, the tensioners don�t leak as much when the car sits and when the 0W starts shearing the 5W doesn�t as much still 6-7 months oil changes at approximately 2500 miles. Car doesn�t seem to use any oil, filters look great, oil is cheap insurance. Almost 12k miles of ownership.
This is a great video on bore scoring from Flat 6 Innovations. I linked it to where they have heightened audio of the sound from scoring. Then they demonstrate on a pulled engine block how the piston is causing that sound. My new to me 1999 with 99k appears to have the same sound, so now I'm totally freaked out. I had already scheduled an inspection before I heard the sound, but now it's going to be a long 15 days waiting till I can drop it off... (no smoke on start up or warm running, no soot anywhere)
Link to Audio start potion
You Tube
I appear to have exactly the same noise..
You Tube
Ben, i wouldnt jump to any conclusions. What are you going to have your indy do? Drop the sump and scope it?
Have you thought about testing the oil before you take your car in? It will give you and your indy some useful info.
Oilvue.com and speediagnostix.com
If you make the exception a general rule is hype.
There are more M96/M97 engines produced than the total of air cooled ones. How many of them have bore scoring problems? How many of them are due to improper maintenance and the late adoption of fully synthetic oils in the US? (even today...)
All I heard there is a running engine and a running engine will make noise. No need to overreact until you have some hard visuals, be that bore scope images or some hard numbers from an UOA.
Skip - per your suggestion on here, I'm giving oilvue a try this week. I have used SpeedDiagnostix for the last few tests so curious to see how it compares. I'm most interested in their soot measurement that I think they provide.
I listened to that. And I am also a paranoid freak lol. As I stated earlier, I hear a tick when the car is started after multiple days of not being used. Goes away in under a minute. Never makes the noise again. Your car sounds normal to me. Raby's tick is harsh. The "tick" you hear doesn't sound harsh at all. Sounds normal to me.
And this year, I decided to not change my oil in the fall. My car was last started around Oct 20. Oil has 1500 miles on it. I will be changing the oil in the spring. Car will not be started prior to the oil change. So essentially parked for 6 months without being started.
If oil doesn't age when exposed to air, then it doesn't matter if oil is changed in November or April. If it does age when exposed to air, the changing it in the spring makes more sense IMHO.
Lastly, since my car is only driven for 6 months annually, I really can't get my head around oil changes every 6 months regardless of mileage, especially when the car is not started for 6 months.
Time to reframe the argument.
Bore scoring isnt an engine issue, it's a lack of oil lubrication issue that has occurred in 986,987,996,997 and time will tell with 991 & 992 engines.
So human nature is that we blame the engines instead of blaming the procedures set forth by Porsche thru their factory maintenence recomendations such as 15k oil changes, as well as blaming the misguided maintenence history, start up procedures and driving habits of the previous owners of the car.
The questions everyone should be asking is what causes the oil lubrication issues in the above mentioned models and what can we do to mitigate it so as to prevent Bore scoring.
We all know the answers,
(1) keep your oil fresh;
(2) use high quality oil and fuel;
(3) keep your fuel injectors, plugs, coils and maf fresh;
(4) pay close attention to your start up procedures;
(5) and when you start and drive your car, try to put at least 30 min of drive time to get the engine oil good and hot to burn of the moisture.
(6) if you aren't going to drive it in the winter months, don't start it. Use a trickle charger instead.
(7) test your oil every so often to see what's in there.
(8) after every oil change, check your oil filter for debris.
(9) drop your sump every so often to see what's in there.
(10) scope your bores from the sump to see what you have.
It all comes down to fresh oil and preventative procedures on any engine. Take your pick: 986,987,996,997, and maybe even the 991& 992. Time will tell.
I have a Ford too! It's got a faint unknown burning smell too
I hope so-- it still sounds the same to me, but my ears may be in cahoot with my paranoia.
Oil is only 100 miles in, so not sure testing it would show much. Indy is a post-inspection service. Starts at 2-hour standard inspection, then goes to other increments depending on what and if he has other concerns. He was referred to me from neighbor who has his 996 Turbo and current GT3 (street and track) serviced with him. So feel confident in that. Just have to wait till 12/15
I am prone to that--- but that sound is just so eerily similar ( this member has had the same sound issue for 5 years and seemingly okay! though my knock sounds more like FSI's than this one I think - only increasing the paranoi!)
https://rennlist.com/forums/996-foru...-rattling.html
Ben, something to think about...
If you are losing sleep over bore scoring, then you have to drop the sump and scope it. No other way to confirm or deny. You may already have spoken to your indy about this, but if not, do yourself a favor and tell them you want to sump dropped, oil fimter analyzed and a bore scope done from the sump. It's not a common procedure, but it's becoming more common. As the Nike commercial says, "Just do it!"
You will be glad you did regardless of the outcome.
Have we seen confirmed scoring cases in the later 991.2 cars? It definitely might be too soon to say anything about 992 but I was under the impression that later 991 cars and on were switched to sumebore technology for cylinder surface treatment that should be much more durable. That said, with enough will power and some questionable practices one could score up a freshly built motor with Nickasil liners.
Pete, you may be right and i may be wrong. I thought i saw thread referencing it RL. I will adjust my comment on the original post to "time will tell".
Thanks
No reports of any bore issues with SUMEbore. We have seen 991 bores fail that were alusil, just like the other 9a1 engines used in 997.2.
SUMEbore has been vert effective in all applications where it was used, except the Ford Coyote. VAG uses SUMEbore across the board with gas and diesel engines alike, even the large Scania and MAN diesel engines use this process.
This is a great quote that is very accurate. Previously before Mr. Raby shared the sump inspection process people were spending more money to perform a boroscope inspection through the spark plug holes only. This only shows the side of the bore above the piston at bottom dead center and one half of the problem area. Most all early onset scoring shows up at the bottom of the bore which is covered by the piston at BDC. The alternate method of scoping with the piston at TDC from the sump access shows the area of the bore most susceptible to scoring.
This is faster, cheaper and more effective than a spark plug inspection. If you do it at an oil change you can pay an extra 2 hours of labor and know exactly if you have an issue or not.
Sadly too many buyers still don't know this before they buy, and they have the scoping done later, only to find out that they have big issues that puts their love for the car to a test.
Yes will discuss with him. He's highly experienced Porsche mechanic so will obviously get the truth from him. This post was just all me trying to figure things out pre-appointment. 13 more days!
Did you ever listen to a drug advertisement on TV disclosing all of the potential issues of using the drug. As you are listening you say to yourself, holy crap...
Some Rennlist threads are like a drug commercial. It will scare the hell out of you until you are able to process all the info and realize that our threads are a clinical discussion of potential issues and solutions that are good to know depending on the path you choose to take. Not an everyday occurrence.
Get some good sleep tonight. The 996 is an awesome car with a very durable engine. Regardless of what your indy finds or doesn't find, there is a solution. That's the beauty of owning a 996.
A chevy small block, a ford small block, a Dodge slant 6, and Porsche Metzger motors are very durable engines. I know this will **** of some people off, but the M96 is far from durable no matter how good you take care of it.
It doesn't **** me off, some people look at things differently, some look at problems as opportunities to create/fix..
What do you think would be the first thing most likely to break on your M96?? ( that hasn't already been improved with a updated version)
I would have to go with bore scoring as the most unimprovable design flaws. The IMS bearing is obvious and can be helped with updating, but damage could already be done by the time a new owner gets the car. There is also the timing chain guides and oil pressure issues. At least for me, the list is too long to gamble on. M96 motors are 20 odd years old and need significant attention that is expensive, for the same money you could get a 996TT and not have to worry about it and you would end up with a much faster and more desirable car that will hold its value better.. It kind of seems like a no brainer to me.
I think engines that use no oil and/or have over fueling issues ( bad MAF sensor or fuel injectors) are more likely to have bore scoring than one that uses a quart oil every 1k miles ( more lube on the cylinders) ... I often wonder if using a "top end lube" would prevent borscoring by adding more protection for the cylinders...
Other issues such as IMSB and AOS and oil pressure have very dependable fixes. Chain guides are a wear item and the newer version are much more durable...
I have actually seen more timing chains snap on 996TT engines for no reason. There was apparently a bad batch of them used, and of course everyone knows of the coolant pipes that need engine removal to fix ( pinned or welded) ... All engines will eventually wear out, someday someone will be crying over the cost to rebuild that 996TT .. it is much more expensive to rebuild a 996TT or GT3 engine than an M96...
you make some good points. In the 10 odd years ive owned a 996TT I have maybe seen 2-3 catastrophic engine failures pop up on the forums. We see that many every month here on the 996 n/a forum...Failed coolant pipes are an inconvenience at worst and a pretty easy and cheap fix in the scheme of things. Agreed, all engines were out from use, but the M96 has a tendancy to grenade itself that is higher than it should be. Replacing/rebuilding an M96 costs more than half the price of the car which is kind of nuts if you think about it.
I tend to not think in terms of $$$$$ , but I know that many/most people do....( I actually bought two 99 996's and a 2002 Boxster for under 20K and four m96 spare engines with minor reparable problems for 7K over the years) . My daily 996 has 190K ( I put 90K of them) and it has never left me stranded or broken down. The closest it has came was recently when I was experiencing a failing CP Sensor, I had to wait for an hour for the Sensor to cool off or spray it with something to cool it off before I could continue on my journey...A failing CP Sensor can happen to car no matter the brand/engine , even Toyota..
I run it hard and even use it for testing new things. I have removed the engine for IMBS update and of course have the UAOS/UIDS installed on it..But I use quality oil and monitor everything closely and take care of anything that can shorten the life of it ..
Not everyone wants/needs a Turbo 996 ...yes I would love to buy one with a blown motor and a few spare motors with minor repairable problems, but I can't afford that, so am truly happy without... ( also, I think I am cured of my boost/power addiction after setting a few world records years ago..lol)
Skip - this is an interesting statement and sort of makes sense. I assume this means that the oil is getting past piston rings, specifically the oil control ring and the car is not consuming oil via bad AOS or a leak. Speaking with one local shop, they have seen a few cars with bad carbon deposits on rings which caused heavy oil consumption. Result of long oil drain intervals that caused this over time. This is something rarely discussed anywhere in the Porsche world but seems to be a huge problem with some cars - Prius being one example. That's right - a Toyota, believe it or not. Quite a few injector cleaner and gas additives tend to claim to add upper cylinder lubricity so might not be a bad idea to use at least every so often.
Yes, oil getting in the cylinder via AOS is a bad thing, even a little, ( due to carbon deposits and also emissions) ,but oil getting past the rings in a small amount is actually expected/excepted, and even beneficial in a small amount as it will lubricate/protect the upper top ring/cylinder ...Just looking at cylindesr that have not scored you can see exactly where each ring stops it's travel..When the cylinder fires the pressure expands the top ring very very tightly against the cylinder. If this breaks loose a particle of silicone it will be dragged down the cylinder just under the top ring and then be rubbed up and down between the piston and cylinder creating a groove and breaking off more silicon..
I have involved with 2-strokes all my life in Racing dirt bikes and outboards and cylinder/piston scoring has always been an issue for some people. Since 2-strokes have no oil sump around the crankshaft all lubrication has to be pre-mixed or injected in with the fuel . People who use the wrong mixture or try to cheap out on top end lube usually pay the price...It just seems logical that a quality pre-mix lube injected in with the fuel would do nothing but help protect the cylinders.....The only risk would be carbon build-up on piston tops or may have to replace the cats a little more early/often like maybe 80k instead of 120k ..
It would be one hell of a thing to prove/test though .....would take years and years...
That guy is notorious for stating incorrect or inaccurate information. First thing out of his mount: "First of all, a 996 is not common for bore scoring because it has steel sleeves and not the coated sleeves". I stopped listening after that.
TAKE A GOOD LOOK at this list of Alusil engines.
What we are discussing here is not just porsche engines, it's Mercedes, BMW, Audi etc. But most don't know it because they don't keep their cars long enough to know any better.
Good news is we know what to do to prevent it and/or treat it compliments of the RL forum. Unfortunately, the other guys don't.
https://en.m.wikipedia.org/wiki/Alusil
from the comments of that video:
"
The M96 had a different composition Lokasil sleeve cast into the cylinder case and the piston skirts had a ferrite coating. Due to government regulation the M97 had a less durable coating on the piston skirts and the new Lokasil sleeves destroyed the piston coating and then the sleeves. In some ways the M96 5 chain was better than the M97 3 chain engine."
"The ferrostan coating on the 996.1 pistons was replaced by a non-ferrous material (grafal) to comply with environmental concerns about production by-products starting in '02. The grafal was far less durable than the ferrostan and led to bore scoring earlier in the engine's life, especially with fuel injectors that leaked with age. The early cars are still susceptible to bore scoring due to the lokisil cylinder material, just takes longer."
and of course the definitive:
"996.2 gets bore score not the 996.1 I had both"
This guy had both. End of discussion. /thread.
Wow, lots of disinformation in such a short amount of time.
I guess someone should tell Jake Raby that Nathan said the M96 doesn't normally have bore scoring.
Jake has had lots of customers send them their engines for no reason. "It's just cosmetic!"
Also tell Charles Navarro at LN that he doesn't need to sell Nickies anymore, Nathan says it's not needed.
On another note, I saw a 4 YouTube series yesterday that showed the process of boring the M96 cylinders and installing/boring/honing steel liners.
While I believe that Nickies are superior, the process was interesting to see.
The machine shop that did the work, did not look nearly as clean as the LN Engineering shop. (I've watched videos from them as well)
The steel liner machine shop looked like what you'd expect for a budget price.
Here's part 1:
You Tube
PCA was just at our facility the last two days filming a 4 part series on bore scoring. Lake Speed from Total Seal, previously from Driven & a Certified Lubrication Specialist, and Mark Malburg from Digital Metrology, consultant to the OEMs with decades of experience with engines and cylinder geometries, came in to participate and to share their extensive knowledge.
Hopefully we'll be able to put a nail in this one and move on from these videos put out by YouTube certified mechanics.
In the last week we've received 12 blocks and 4 had been either dry or wet sleeved with steel sleeves, one even with a d-chunk welded up and sleeve installed in that one hold and the other cylinders were left alone which ended up scoring. It would seem there are more shops doing questionable work. It's bad enough to have a failure but to have to pay twice to rebuild the engine is even worse.
Where would you prefer to send your expense Porsche case?
Here:
or here:
Call me OCD, but the huge mess in the background of the first photo makes me think they’d lose my case.
There were other screen shots in the other videos that made it look like a hoarders episode.
Also the equipment LN uses is MUCH more advanced.
I will add that it's not only equipment. Although I do give my guys carte blanche when it comes to anything for the shop so we have the best equipment and tooling, with exception of my youngest machinist that I hired out of the local community college machine shop program, each of them have decades of experience and most of them are car guys too. LN used to outsource all our machining and the local shop I used ended up closing and a good number of the guys who had been making our parts there eventually all ended up working for me once I made the decision to expand and bring all the manufacturing in house. The end result is we have very talented guys that I've worked closely with for over 20 years and they are who make LN the success it is.
I watched the whole video series. I found the series to be quite good and detailed. I would suggest that although the shop isn't as pretty as LN's, they did seem to know what they were doing. Older equipment doesn't mean that the work is not done properly. With the lack of automation, the machinist really needs to know what he is doing.
Many years ago, I needed an alignment. Tried a shop with the "new" laser alignment. Car still wasn't good. I went to my neighburhood specialist that all he did was front end work. 6 bay shop. Alignments were done with chalk, measuring tapes. Techs knew what they were doing. Every car was test driven and then minor adjustments were made to make sure the car was perfect. Wheels were always balanced on the car and lug nuts marked.
This was not a race shop or a high end shop. Just a good, dirty shop.
If I could use LN, I would. Being in Canada, although possible, it becomes a complex proposition. When the time comes, I hope to find a local shop that can do the work.
You sir, are mistaken. Unless your rebuild was performed by FSI\LNE then it's crap, it WILL fail, and you'll end up sending it to them anyway since they are the ONLY place in town (USA) that knows what they are doing. /sarcasm
We get tons of blocks from Canada. Not an issue. We have had enthusiasts send us cases and all the IMS Solution Certified installers in Canada have taken Jake's hands on classes and send us blocks:
https://imssolution.com/certified-installers/
We have two blocks here from Hong Kong and have recently done blocks for customers in Australia, South Africa, and the Netherlands. Shipping is a non-issue as long as you package the block properly, do the paperwork right, and insure it.
I thought of you as an example where iron sleeves can and do work when done properly. Conveniently, we always hear of failed attempts at iron sleeve option but when it does work it's quietly dismissed and not talked about. They can and do work when done properly. There are tons of shops that support race cars, rebuild engines and do amazing work but just choose to keep their head down and churn out solid work without advertising on forums. You never hear of them unless you seek them out. They're plenty busy, trust me. I've purchased and like LN products a lot and appreciate very much what they do for the 996 community. That said, everyone is on that bandwagon and any other option that is proposed is immediately shut down based on legacy information that may not reflect the current situation. As a customer, you want to have options. Options are good and dismissing anything other than the big player in the space is not helpful to the community at all. It's also downright disrespectful to the many shops and people that have been working on P cars for longer than some of the big players have been around.
My local machine shop that I use for valve job, head work, and some air cool case work has a very messy small shop. Messy as in untidy, dirty floor, spare parts everywhere, unclaimed customer pieces over flowing, pieces of cuttings can be found wall to wall. I would prefer my shop to be clean and tidy because it is just a safer place to be. But, I close my eyes and take some work there anyway because those local shops are harder to find and he has always done excellent work for my Ferrari 355 heads multiple times. So, a messy shop can do good work. But I doubt that my local shop can scale up to do twenty 996 cases a year.
For the 996 engine I just did, I went straight to LNE. And for the 997 engine I am doing next year, it will go to LNE. I have not seen their shop, but there is something to be said for having done it a few dozen times before.
I had the IMS solution installed in my car in 2018. The installer had been certified by LN. In 2018, he no longer was certified. In 2018, the closest certified installer was in the Toronto area but I had not heard good things about him. Today, the closest certified installer is a 5 hour drive away. I'm not sure how these shops loose the certification. I should also say that I live in Toronto - biggest city in Canada. Only Mexico City, New York and maybe LA is bigger than Toronto. I would hope that there were more specialized shops in the Toronto area. At most, there are maybe 4 competent indy specialists.
Porsche market is huge in Toronto. I can walk in 5 minutes to at least 10 911's.
If I do encounter the misfortune of needing an engine rebuild, I would likely reach out to one of these indy's and let them do their thing. My preferred indy, does list on their website using LN products and state the following "
We will rebuild your engine using LN Engineering as the machine shop & supplier of the upgraded weak points"
I've been to the shop when they were doing a rebuild of an M96. Although years ago, looked like they were putting the whole thing together after the machine work was done.
And I hope that everyone understands I'm not bashing LN. On the contrary. I didn't hesitate to have the solution installed within days of getting my car. I think they are the premier M96 engine builders. Unfortunately, very long wait times.
Understood. Not taken negatively in the slightest. The good shops have plenty of work and large backlogs, so getting a car in, engine pulled, disassembled, and case halves shipped to us can take time.
We however do everything in our power to get blocks turned around in 6-8 weeks. We do our part in about a week, but the plating process can get slowed down, especially in the winter. They do offer rush service, but usually it's not necessary as we're usually not the limiting factor for most rebuilders.
We also stock 6-9 months of inventory of everything needed to rebuild these engines as well so we can support those shops that partner with us. For example, Mahle Motorsport is still at 26 weeks for pistons and during covid it took 40 weeks to get head gaskets, so we make sure we order well in advance and in large quantities.
Idk, I am an FSI owner for just over a month. I approached it with a completely open mind, honestly if it all went to **** and sucked I was/am ok with it. The transformation to this point is nuts, this is what the 996/997 should have been from the factory. $30k on a 996 +$35k on an FSI build, I do not think you will find something that will put a bigger smile on your face. I have a thread with my experience and if it starts to suck I will be 100% honest, but right now the difference is dumb and I haven�t made it through the break
https://rennlist.com/forums/997-foru...s-build-2.html
I got an LN 3.4 to 3.8 M96 kit dealing with them from Australia - for my Vesuvio 996.1, elective rebuild, as have other Aussies on our forums. . As supply chain issues were already affecting my other GM car projects. I went with the LN Nickies, deluxe kit, IMS Solution, and many other in stock items from LN.. It was more professional, low stress and personal to deal with LN, than local Australian suppliers. than on my local projects.
Just got back from a PPI on a 2002 Carrera 4 and it had bore scoring. Went to one of the best rated Porsche rated Indy�s in my area they said out of the last 5 996s they have done PPIs on 3 had bore scoring. Feeling pretty defeated.
Where are you shopping? I could see that if you're in a colder, low income area looking at cheaper examples with limited service history. Try shopping in some warm climates and look for cars with frequent oil changes. I think you might do better.
In Toronto so warmer is hard. But I appreciate the tip. Are the non scored engines not just doomed to start scoring by design at some point if I live in a cold climate? Planning to buy a Carrera 4 and drive in the winter. Seems like it might not be realistic.
I don't think it's unrealistic. Just might have to look a bit harder or buy from out of the area. From what I've heard it's really important to start driving immediately at low RPMS in colder temps. avoid excessive idling and do frequent oil changes.
the bore scoring comes letting the cars idle in the drive way to warm up when it was freezing outside. and following the original factory service interval, which was 10,000 miles or more. explains why there are so many cars with some scoring.
Edit: I don't think they're doomed. You can easily stay non-scored and light scoring is not really that big of an issue. Its is problem many people live with.
Plenty of good ones out there and plenty of bad ones. Remember its a 20 year old car and if it had lots of owners and very few service records, there is a pretty good chance it was treated no differently than a 20 year old Toyota Camry. Very few oil changes, 20 year old fuel injectors, plugs, coils, etc. You get the idea. You will find a good one. But start with getting the service records. Imho, no service records means it's a waste of time.
And those remaining two had probably already problem fixed ie. Nikasil cylinders
Seriously - considering that there are so many contributing factors to bore scoring and since that is the Achilles heel of that engine it's inevitable that sooner or later - if nothing else - it'll develop bore scoring as it's a mechanical thing that wear when they are used.
But the car itself is not doomed. It's a wonderful car and fixing that
properly
solves the problem - that of course requires some "small investment". Over time things will get better because these cars are being fixed all the time with a proper solution.
Let's reframe the argument.
It's a tough concept for many to grasp, but with any 20 year old Porsche, Ferrari, Mercedes, BMW, Audi, Toyota, Honda, etc, you are BUYING all of the previous owners maintenence history. They either did the right things to, with and for the 20 year old chunk of metal, plastic and rubber or they didnt.
If they did the right things, then the engine is most likely in great shape and can continue to be for long in the future with the right service, maintenence and procedures. If they didn't, then you will have a problem on your hands. This is why service records, ppi and bore scope are so critical to confirm the condition of the engine that you are looking to buy.
With all this being said, it is inevitable that every engine known to man, sitting in any car from any car manufacturer will someday need an engine rebuild. Why, because metal eventually wears out regardless of whether the engine was well maintained or not. It just so happens that a well maintained engine wears out a lot later than does a poorly maintained one.
So if you are looking to buy any 20 year old car from any manufacturer, get its service records, perform a PPI, test its oil, drop the sump to see whats in there and scope the bores. If everything passes, then it's a pretty good chance that an engine rebuild is way off in the future.
However, if their aren't any service records and it doesn't pass its: PPI, oil test, sump drop exame and bore scope exam, then you have a ticking time bomb and a rebuild will be needed shortly.
Nothing wrong with buying a rebuild candidate, especially if the rest of the car is in great condition, but you better lowball them with a price that takes into consideration a rebuild.
Conversely, no reason not to pay up for a car with an engine, exterior and interior that is in excellent shape, and all of the right things have been done to it when they should have been done throughout its life.
Keep looking, you will find a good one.
Just be glad you aren't looking for a 20 year old Ferrari, Lamborghini, McClaren or Aston. You would need a printing press to keep them in good running shape. If you want a high performance classic sports car, the 996 gives you maximum performance and enjoyement with minimal costs in relation to the other classics. That's is one of the most beautiful aspects of the 996.
That really sucks. I'm also from Toronto. I purchased in 2018; an '03 C2. Had the full PPI done at Autowerks in Vaughn. Stage 1 of PPI was overall condition, then Stage 2 PPI was leakdown and borescope. In 2018, the tech (and owner) told me he had seen very few failures of the IMS bearing or bore scoring. Said my car was good. I did post on here and a local Toronto guy did comment that his 996 a C4, did bore score and he was none to happy about it and turned him against the 996 and Porsche's in general.
I will say that every time I start my car, I listen for the tic tic. I get weird noises from the car that go away in 30 seconds from starting when the car hasn't been driven in a couple weeks. Always kind of concerns me and does indeed does take away some of the enjoyment of the car. Anytime I take it out, I wait for it to get up to operating temperature. I won't even back it out of the garage to wash without driving it to get up to operating temperature.
I don't know this car or the owner....Have you looked a this one:
2004 911 C4S (996) � UCR Porsches for Sale/Wanted | PCA UCR
How bad was the scoring? To be fair the vast majority of 996s will have some cylinder wear. The difference is what's normal use and what is problematic. In Toronto any 996s that have been driven regularly in the winter will likely exhibit it more. Which indy did you go to?
Let's say you go through a PPI including bore scope thought the sump and you/shop observes the start of scoring. Do you offer just about the value of a roller and start the FSI/LN process or just walk away and keep looking? If she's still running and in the early stages of bore score, do you keep up oil changes/maint. and drive for a year or 3? I think if I'm in that position, IF there is no obvious engine tick, I would try to get a deal. Dive for 5-10k miles with oil change and bore scope every 3k miles. That might get me 2 to 3 years of a weekend car and plan for a winter time engine out service.
Ha! I do the same thing with backing it into the driveway so I can work on the other car. To my wife, "Honey, I'm moving the Porsche to the driveway, be back in 45 minutes, do you want to go?" :-)
It's kinda funny, but at the same time...kinda not.
Does sound pretty funny doesn't it.
In reality, I pay attention to this in the winter months when the car has been sitting for extended periods of time. In the warm weather months where I am driving the car frequently and therefore oil has been circulating and lubricating the engine, I don't give it a second thought to start it move it and then shut it down. But I will turn the key 2-3 times before it fires up to get things turning whether its the summer or winter.
These engines don't have to be babied, but they do need to be lubricated with clean oil. But what 20 year old engine doesn't.
I would offer roller, or roller+, pricing and plan to drive it as-is until I had all the parts (and time) necessary for a quality 3.8 rebuild.
My next planned engine (likely a M96.01) will be rebuilt by me just to have something to do in my spare time after retirement.
My next 996 build (at least my current thoughts about it) will be different than my current 996.2 interior & exterior-wise.
I won�t be in a rush to finish since my current 996.2 will be available to go have fun!
I'm in Toronto driving a C4 cab year round...of course, I've got Hartech cylinders now.
It's not about the cold. On the rare occasion that I start the car only to move it (we have a narrow driveway), I can see next time I start it there was probably unburned fuel left from the last time. I really try to avoid that, but I'm less concerned about it with the new engine.
There are some that say you'll find signs of wear on any and every 996 or 997 you scope, however that's simply not the case - there is no "normal"
996 bore scoring
. If you find an engine with early stages where there are no symptoms, we've seen those cars go upwards of another 10k miles as long as you correct any problems that are contributing to the issue. If a weekend driver, the car could last years. That said, you shouldn't pay top dollar for a car that already has bore scoring knowing there is no way around your having to pay for an expensive engine rebuild.
Sadly, we see many examples where sellers either knowingly or unknowingly sell cars with bore scoring, so doing a pre-purchase inspection with scoping of the cylinders is a must for any 996, 997, or Boxster/Cayman with the 3.4 liter engine.
It's important to change to an engine oil with lots of moly, like Driven DT40. In warmer climates, you can even get away with running Driven FR50 or DT50 instead, which would provide even more protection. Reducing the oil change interval to 3 months or 3,000 miles can't hurt either. I'll add that I personally would not track any car with known bore scoring.
I don't think it's necessary to repeatedly scope the cylinders since you already know they are scored. I would however continue to do used oil analysis to monitor the wear levels. You will know when it's getting bad. End stage bore scoring will result in very high oil consumption and even misfires because the plugs end up getting fouled.
Just to calibrate myself, this is a picture scoped from the top of a 997 Cyl 6. Bore-scoring is clearly visible to the left. I classified this as intermediate stage, and gave it 5,000 to 10,000 miles before it needs a total rebuild.
Charles, where would you classify this engine?
Are there any
996 bore scoring
symptoms, especially ticking (piston slap) or excessive oil consumption. I'd gauge how for it is along based on these factors. I'd say it's pretty far progressed visually. The 10k miles I quote is based on finding very little at BDC when scoped through the sump.
I would say that engine would not be "fit" for any Track Events, but like Charles mentioned it can still have a few years of "normal driving" if there are no signs of embarrassing ticking noise or excessive oil.consumption...
Measuring the Blow-by is a good indication of how "fit" the engine is....
As a comparison, here is a picture of a Cayman S cylinder 6 that had 170 LPM of Blow-by , it had no ticking noise, and the oil consumption was modest, but on the Track the blow-by was excessive enough to cause the AOS System issues/smoking on high G force corners that cannot be corrected...( except to correct the blow-by issue)..
170 LPM Blow-by
#6 piston 170 LPM blow-by
On my own 997, here is Cyl 6, and it has piston noise, very high oil consumption, and sooty exhaust, and it needed an immediate rebuild.
This is my neighbor's 997, cyl 6, same 3.8S engine. It does not yet have loud noise, or high oil consumption. The tail exhaust pipes are just getting darker.
I am firm believer in high quality oil film protection , and the extra heat and pressure that is exerted on the #6 cylinder upper thrust side constitutes the need for more robust oil film protection than most engines are getting.
To Prevent bore scoring I would recommend that a more robust oil with High Temperature High Shear Viscosity be used , like a 50 weight or even a 60 weight...
Since the bank 1 side has the same cylinder and ring materials , and is not prone to this type failure ," the straw that is breaking the Camels back" is the extra heat and pressure, and a higher HTHS oil film WILL stop this failure.
Even a 20w-50 oil can be safely used in temperatures down to 14F ...of course if you are operating in temperature below that ( 0F or below) , you would want a thinner oil ..( 5w-50 or 10W-60 )
IMHO a 0W-40 or a 5W-40 just can't protect the bank 2 thrust side, especially #6 cylinder...
Remember that the 0W-5W-10W-20W is the "actual weight " of the base oil in mutiviscosity oils.. then the polymers are added to make to 40-50-60 weight when the polymers get hot and expand/thicken .....but the polymers get chopped up by the chains and gears and can beak down with "high temp shearing" , and is why I recommend the most robust oil to begin with....
1999 C4 Cab, 3.4L (posted in the bore scoring poll but thread bump here to get some more eyes on this)
Checking the cylinders while I have the plugs and coils out. 1-5 look fantastic. I got to cylinder 6 and just about had a heart attack with the black "bore scoring" looking marks.
One member suggested it was maybe carbon buildup so I went back in with the camera and took some more pics and made a video. Sure enough, there are some carbon deposits floating around and the valves look to have some on too. Is it possible that this is carbon and not the dreaded scoring?
Car has no symptoms of scoring otherwise. No tick or knock and no oil consumption over 1 year and 1900 miles. Sent the oil out to Blackstone. Sump was mostly clean, say for a few little brown pieces that I assume are from the timing guides but very few and very tiny.
Pics and link to vid below.
Thoughts? I put a bottle of driven injector cleaner in about 150 miles ago. If this is carbon, should I run several tanks and several bottles through and recheck?
Unfortunately that's scoring. Time to swap in DI40 or maybe even better, DI50.
By the carbon on the piston, it's been burning oil for a while.
I'd be curious to see what the UOA looks like.
I just ordered a new oil cap and manometer to test the UAO as I�ve been digging into this topic all day. Hopefully that will give me some answers. It�s off the road for a few weeks while I wait on coils and plugs.
thank you for the response, I appreciate all the feedback as I�m still new to the 996/M96.
I'm guessing it�s early on as I have no smoke, no oil consumption and no tick�
I'd wager you still have some time based on your current vehicle usage. Just would be a good idea to make sure you don't have anything specifically making the problem worse, like fuel washdown from a bad injector, etc.
https://lnengineering.com/products/w...e-scoring.html
thanks for the link. I was also looking at the procedure to extract injectors for a service�.especially as I only seem to have this carbon issue in cylinder 6
Cylinder 6 is a common location for bore scoring. From this perspective you would expect carbon deposits to be higher in this cylinder. If you extract the injectors it would be best to replace them and not try to clean them.
Circling back to the above messages. I got around to doing a Manometer test. Engine at operating Temp.
Car OFF : 0.10" h20
Start brief Spike: 7.03" h20
Idle: 4.53" h20
I think those are all within normal specs. Plan to check cam deviation and fuel trim next.
Also got an oil analysis back. This was my second oil change and second analysis. First change and analysis was when I got the car with little to no history of last service (first sample unknown oil and mileage, oil change 2 is mobil 1 5w50 no additives). This oil interval was 1 year and 1900 miles. Iron appears to be high still...
My feeling at this point is keep an eye on it, keep changing the oil. I've got the LN magnetic plug. Also running 2 tanks of techron then re scoping Cyl 6 to check on the carbon and the scoring. I'll fix it when it needs fixing, for now i'm gonna drive the heck out of it and enjoy it for all it's imperfections!
Side note, This oil change I put in Liquimoly 5W40 and Ceratec and I must say it the motor does seem quieter and the initial 1 or 2 seconds of chain rattle aren't there now.
This is a source reference. Confirm exact model applicability in the original material.
