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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHM96 Engine failure teardown this weekend
Reported or suspected cause
ignorance
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
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Leading evidence: 'ignorance' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'ignorance' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check ball backed by a spring' (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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Performed · outcome unconfirmed
Thanks Tippy - I checked their parts catalog for a decent picture first time around, but it was a generic lifter, and not a good shot at that,
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Performed · outcome unconfirmed
The cylinder is actually a rather porous insert with a high content of silicon that is fitted into the engine block mold and then during the casting process molten aluminum flows into this insert.
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I've never heard of cast iron cylinders cracking although most iron block engines used a closed deck which supports the upper cylinder wall better.
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Performed · outcome unconfirmed
I have used Mobil 1 mainly 0W-40 but sometimes 15w-50 and even 10w-40 exclusively since buying the car new.
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Suggestion
Should this spring fail or the check ball develop a leak this would allow oil to flow out under pressure of the valve being opened and a noisy lifter the result.
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The cylinder is actually a rather porous insert with a high content of silicon that is fitted into the engine block mold and then during the casting process molten aluminum flows into this insert.
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Suggestion
I do know people that are afraid of expensive repair bills from dealerships (including some that trade cars in once the warranty expires), hence why I said it could turn others away from the car.
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Suggestion
I think if some of these could be done in conjunction with other "normal" issues like replacing a clutch or something, it might be well worth the effort to do....
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99 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
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If you are in the area feel free to stop by my place this saturday (1/17/09). A friend (easy C on rennlist) had an engine failure last year in his BoxsterS and we will be taking it apart in my garage. I will take photos. There will be a few PCA guys there. Beer is included with the admission price of $ 0.
The fun starts at 11 AM.
PM me for the address if you want to attend. I am in Georgetown, Kentucky.
Hopefully, it doesn't look like this:
Seems pretty simple once it is torn down that far, doesn't it? I figured it would be easy to find someone adventurous at a machine shop who would be willing to fix that cylinder wall as a challenge. Couldn't even find someone who would look at it, even after I gave them the "you can repair LOTS of 996 motors" pitch. In the end, the Man won.
I hope yours turns out to be a head gasket or something easy(ier).
Good luck, wish I could come get in the way/help/watch.
How can you be doing a failed M96 block tear-down?
I've been reliably told, on this very forum, that that's statistically impossible/unlikely/irrelevant.....
I know your statement was probably "tongue in cheek" but it IS virtually impossible if you a) got Porsche to replace your engine under warranty or b) bought a new engine and did a core swap to reduce your cost. Either way, you would not have the old engine to tear down.
However, if the car was out of warranty and you didn't want to buy a new engine, then you still have the engine to tear down.
I think the sarcasm resides more in that, he thinks the M96 fails a lot and he thinks many of us who try to point out that that is probably not true are wrong...
Not my engine. My Boxster is running fine. They guy who had the engine replaced it with a 3.6L engine. His Boxster has a little more zoom now. I will take photos but I highly doubt my wife will be anywhere near the garage tomorrow!
Not the engine police but the validity police. Something which you have no desire to learn and something you instead proliferate with hysteria and inaccuracy. And you wonder why so many people get bitch-slapped for asking questions like "Interested in a 996 but I have read here that these cars are prone to failure, what do I look for". People like you create the hysteria instead of trying to support the argument (either side) with facts. All I have done (and others) is try to get you to support your argument with fact instead of anecdote.
Not going to get into the same argument with you anymore. You know my stance, and I know yours. Enjoy.
Unsubscribe time
How could you be driving one??? I've been reliably told by people on this forum that all of the M96's fail....
Quick sell your car cdodkin.......she's gonna bloooooow any second...
Naah, I'll hang on to this one thanks - the last two blew, so what are the chances of the third one doing the same!
Apologies for not including you in the list of Engine Police - not intentional.
Yes, it's a tired argument.
I don't want to hijack this thread too much though. It's going to be an entertaining thread. Good luck, and thanks to the OP. Keep us posted.
cylinder crack failure, as long as rest of engine sound.
One can even elect to take engine up to 4.0l. All it takes is money.
Do not recall off hand if any company in USA offers this.
(Essentially AutoFarm bores out old cylinders and machines block to accept new cylinder liners. These interlock together at top to create essentially a closed deck which helps strengthen the engine.)
There have been some engines in some UK long term Porsche cars fixed this way and so far I've not heard of anything bad.
Sincerely,
Macster.
Well as Judd has said... the engine is (or was) as M96 3.2 from a 2001 986S... The engine died coming out of Turn 7 at putnam park in Indiana... after shifting to 3rd it blew going into big bear... I was towed off, and a tech from an unnamed dealer (NOT Porsche of Lexington) attempted to start the car in "flood mode" and it starting clanking...
The engine had about 72,000 miles on it.. with about 2,000 of the last 10,000 at the Track doing DE's...
I want this to be an informative post, as I think we can all be mature enough to not make this single event seem like every engine does this!!! I know of quite of few M96's running well into their 100+ miles... a few over 200,000 miles!!!
Long story short, my car is now running 7.8 DME with a 3.6 !!!!
Anyways here are the photos from today's dismantling of my original engine... big thanks to my fellow Bluegrass Region PCA'ers, Brian W. from Porsche of Lexington, and of course Judd for lending us his warm garage...
All Thumbnails are clickable, and I guess they explain themselves... looks like cylinder 4 hydrolocked from a cylinder crack... which can be seen on the head side of it in three places on the third and fourth photos on row 4
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If anybody is interested in any of these parts... make me an offer...
Good luck with that assumption. The "all M96 engines are bad" crowd is already circling.
Thanks for the post and the high quality images. Is the 2001 3.2 a variocam plus or regular variocam motor?
Was there excessive wear on/around the chain ramps for the variocam?
Thanks again.
regular variocam... 7.2... now car is 7.8 with variocam plus
yes there was excessive wear on the chain ramps for the variocam... as per our master mech there...
So what's the prognosis - does it look like the constant flexing of the block caused a structural failure in the cylinder wall?
Or did the block crack and take the cylinder with it?
Interesting that it was cylinder 4.
It's more common to find one of the center cylinders cracking.
That's why I was asking if the head had cracked as well, as this is more common on the outer cylinders.
Did you have any signs of intermix or coolant loss before the engine eventually let go at the track?
well none of those signs were seen... it was a friday open lapping day, fairly cool, and on my first hard lap of the day after two warm up laps... coolant and oil were checked that morning as well... also you can see the heads in the photo... the piston themselves were completely destroyed and only a few larger pieces were left as can be seen in the first photo from inside the cylinder... my theory is that the crack in the wall reached its critical point that morning on the track, and trying to start it multiple times later caused the hydrolock... again this is just my amateur theory... Im medically trained... not mechanically...
We are working with LN now on a 4.0 engine based from a 3.2 foundation with our parts and processes coupled to theirs.. I have done all the product testing and development for LN and was their very first customer years ago... We work together continually.
Lots of things never seen or heard of before will be released really soon. We have been busy!
Like I said on 986 forum, these broken pieces are valuable to our program and I'll purchase them for investigation.
I'd have to see it up close and Charles would have the final call in the matter, but I'd say that this block is repairable with LN's procedures. It would be a good foundation for one of our 4.0 test engines.
We see D chunk failures with all cylinders.. In fact #1 seems to be the most failure related cylinder in the 996 while #4 is the most fail prone in the Boxster applications.
We have seen all cylinders fail from all models and years.
Mainly due to the difference in oiling from the opposite G forces the engine oil encounters during cornering, accelerating and decelerating..
In a Boxster the engine is inverted when compared to a 996.
+1. This is a good thread, informative as well. Stop trying to manifest a confrontation where there isn't one. And for what it's worth, I've never seen or heard anyone in these forums or otherwise say "all M96 engine's are bad".
Understood that the 986 has the block rotated 180 degrees horizontally, I have one of each - so the absolute physical position determines the most likely cylinder to fail in your scenarios?
Do you see the lack of lubrication under load as the main issue?
or is the cooling of the block inconsistent for similar reasons, leading to differential expansion and eventual stress fracturing?
my question is:
from looking at the cams and the way the contact the valves, what is used to set the gap? I have "heard" these had hydrolic lifters but from the pictures I dont see anythng there.
Doens't have anything to do with the failure, just the motor in general
Ray, you need to just start to ignore this troll. See post #9 and #12 and that's all you need to know (they are quoted above in this post of mine. Not at any time did you, I, or anybody else come to this thread "attacking" cdod, but instead he chose to post not once, but twice with his usual diarrhea of mouth and instigation to try and pull us in so that he can have some forum to release his irrational unsubstantiated crap. I've decided to quit engaging such bottom feeders. See my last post to him (quoted above as well). Yet I still don't think he will get it. In predictable fashion though he won't be able to keep from posting some sort of irrational rebuttal to you and/or myself.
it was always a center cylinder. My thinking was the block was undergoing some stress/twisting and the crack happened at the weakest point.
Mr. Raby reports the failure is not limited to any cylinder but appears in all of them with no apparent pattern.
Thus this would appear that twisting of the block not to blame.
Several things come to mind: One is that the failing cylinder experiences improper combustion -- detonation or something close to it -- and the extreme pressure spikes cause a crack. I note the crack is always at the top of the cylinder. The open deck design doesn't help.
Another possibility is the cooling of the area that cracks is uneven. Perhaps low coolant or maybe coolant that has lost some of its ability to resist boiling causes an air pocket to periodically form. This allows this area to heat up and then when the pocket collapses the relatively cooler coolant heat shocks this area. If this happens, over and over again, at some point the wall fails.
The Boxster engine can suffer from oil starvation under some circumstances. One is under extreme braking in (IIRC) a left hand and high speed corner.
This forces oil under the right cylinder bank camshaft cover away from the scavenge pump located at rear of head under camshaft cover. A huge volume of oil is constantly fed to the cams and valve gear. It doesn't take much time for a considerable volume of oil (just several guarts is all it takes, maybe less if oil level a bit lower than optimum) to accumulate under the camshaft cover.
This can result in the oil level in sump going down to the point the oil pump may ingest oil with more air in it. If the oil "old" its anti-foaming additives may have been depleted too.
If the main bearings, or rod bearing don't suffer the hydraulic lifters might. With air in the oil these lifters will collapse though how this can result in engine failure I'm not sure. That is causes a drop off in power at higher rpms is a given as the valves no longer follow the desired valve action and lower lift, less duration, etc. work to reduce engine output.
If this air laden oil makes it ito any of the camshaft chain tensioners a tensioner could fail to maintain proper cam chain tension. This can be very serious cause the chain with more slack -- and at high speeds -- jump/skip a tooth and valve contact with piston can result with disasterous results.
Or the chain slams against tensioner that has lost its ability to maintain tension and breaks the tensioner/guide. Same bad result for engine.
Sincerely,
Macster.
Macster - interesting reading, and a very logical review of potential issues - How much of the damage we see is initial failure, and how much happens 'after' the initial failure, either by the engine continuing to run or attempts to start the engine after the event?
Is it even possible to tell after tear-down?
I started reading this thread to learn whatever I can about the project, but I have to read yet another diatribe from cdodkin. Get a life and another car! I and a bunch of other people are here to learn about the engine project - not hear your endless jabs at other members who have a different opinion from yours. You took a great thread and pissed on in.
Bob
Don't worry about his usual and predictable diatribes Bob. He continues to give strength to the kettle-pot theory. I take great pleasure now in watching him continue to talk to a wall as I will not address him anymore.
You're right of course, but I don't really like being pushed around by an e-thug. Judd posts what could be (and hopefully still is) a good thread (informative rather than random speculation) that could illuminate causes of a failure only to have cdodkin lay an e-crap in post #9. I can certainly empathize with someone who has lost two motors, but it's sad to see blantent contempt injected into every topic on this subject.
+1
Honestly, as someone who hasn't been reading this forum until I started looking at 996s, I found Dell and the others posts against cdodkin to be the more annoying and a lot closer to flame posts than cdodkin's posts. Does cdodkin go a little overboard with the engine failure stuff, maybe, but it is something that a perspective buyer should take into account, since there is a chance of it happening and with a 911 it's going to be more expensive than say, an S2000, or an Elise, etc, etc. I don't see the slight chance changing my opinion of the 996, but I could see it being a decision maker for others.
There has been some good info and pics in this thread so hopefully it doesn't die in a dell vs cdodkin arguement like another thread I read yesterday...
You are definitely entitled to your opinion and I respect that. However, you fail to understand the complete history and the reason for the near beatdowns we were forced to give cdod in threads past. Anybody can cry fire in a crowded theater. The problem with cdod is that there is no fire in the theater, just the possibility of said fire.
Not to worry, as the banter is one sided now. I have no desire to address a post of his anymore. People see the instigator in him as evidence by his posts of pleas for people like me, Ray, etc, to chime in and get it going once again. It's one thing to flame somebody for no reason (ala Ben Choi) but it a whole 'nother to try and enlighten the ignorant. Problem is, sometimes the ignorant don't respond to either the initial help or the subsequent beatdown. Time to leave him to his bitterness and gospel.
ps. explain to me (and the rest of us) why a perspective buyer should take into account an anonymous internet poster's overboard opinion on the M96 motor..as you stated??? There is alot of stuff that "can" happen but if you lived your life on what "can" happen, you'd be miserable. These cars are so dang cheap now it's not even funny (numbers produced and the economy) and if a motor "should" need replaced, for a whopping 8K and a 2yr warranty, a modern day Porsche sure sounds like a steal!
The very fact that there are people here who feel that they have some sort of right or authority to hand-out 'near beatdowns', and be proud of that fact, is very disturbing.
But let's not let that get in the way of a good thread.
I understand that, and if you read between the lines in my post (the part about not reading this forum long) I already said that
In my opinion it's wise to gather any information you can about potential problems/trouble areas on a car you are looking at purchasing. It ensures that you are prepared for any expensive items that could fail (no matter how small the chance, I'd rather be ready for it than to be caught off guard and then have to deal with it). I'm not saying you should live your life in fear of what could happen, hell ANYTHING can happen, but ignoring any and all potential issues isn't the best course of action either. I can work on my own car, so none of the mechanical issues worry me one bit. I do know people that are afraid of expensive repair bills from dealerships (including some that trade cars in once the warranty expires), hence why I said it could turn others away from the car. Granted, those probably aren't 911 owners for the most part......
There are enough threads on here about the engines going, a number of them in the same manner, so I don't think it's really just one internet poster's overboard opinion, nor did I mean that (I meant that the fair number of "my engine died" threads are sufficient to at least acknowledge that it's a potential issue one may have to deal with, a sure bet, of course not. Likely? no. Possible? absolutely).
I'm not suggesting that there is evidence that this is a widespread issue/concern (IMO it's not) nor that people should stay away from the 996 just because of the isolated cases of engine problems.
I absolutely agree with you there.
Dave, thank you for your rebuttal. I agree with you 99.9%
Further, I appreciate your candid and polite response. Very classy
Sure it's out there (M96 problems). The problem with cdod is he has preferred to ignore the proper way to support and argument and instead injected falsehoods in invalid arguments which do NOTHING but scare the crap out of potential M96 owners rather than educate them. But I do agree, the heated banter of past has gotten old and does nothing to further the cause. This is why I have elected to no longer response to cdod. He will continue to talk to me directly and take jabs indirectly but I have thick skin and the ability to ignore him
I hate the rap the M96 has gotten but I have had several and even tracked the snot out of them and never had a problem. Many others have as well. I honestly believe that the M96 is one of the most reliable Porsche's one could ever own and will provide for miles and miles and miles of enjoyment. I feel truly bad for the small number of owners who have had an engine failure, etc, (yes, I even feel for cdod). My problem is with ignorance. Spreading "fact" that is unsubstantiated will not be taken lightly.
There are a couple things you just don't do on this forum....
1. Spread hysteria for which you have no evidence to support
2. Come to this forum without posting pics BEFORE your first posts.
separated from the main failure.
I've seen one 996 engine -- I have pictures -- with a failed IMS bearing and teh engine disassembled, on its way to be resurrected.
Besides the obvious IMS bearing failure signs one cam chain guide/tensioner had broken.
Fortunately, the owner shut off engine before the noise he heard from the IMS bearing going to pieces progressed into a disasterous change in cam timing.
But I suspect the above case is a rare one. By the time the noise has stopped the insides of the engine are a mess. If one had the time and experience he might be able to determine what the failure point was and recognize the rest of the damage as that which happened after the fact. For those engines returned to Porsche the postmorteum there might turn up something but Porsche doesn't share this info outside of the company.
Sincerely,
Macster.
in a sliding fit pair of sleeves. These for an open cylinder that receives pressurized oil which makes this sleeve rigid (cause oil doesn't compress very much at all). The pressure causes the sleeve halves to push apart until the bottom part is against the top of the valve stem. The upper part is against the underside of the large round surface against which the cam lobe presses as the cam rotates.
As the lobe presses down the open cylinder makes for a nearly solid connection between the large lifter body and the valve stem head.
As the lifter body travels down its bore it cuts off the oil feed from the lifter galley. This effectively seals the oil that is in this lifter body and the small cylinder contained inside it so the oil maintains sufficient pressure to transfer all cam lift action the valve.
These lifters are amazing devices. I have one on my desk and use it as a paper weight! They work even better in an engine...
BTW, I have pictures of this unit disassembled. If you want PM me and I'll email them to you.
Sincerely,
Macster.
Macster.....you raise an interesting point about the ability to recognize when the motor is starting to have "issue". One wonders if there is a way to have a shut-off system integrated into the design that would essentially stall the motor when a specific code was thrown like this.
How many people find the time to post and start a thread like "My car's engine runs like a top" vs "My car's engine is having problems"?
This forum, aside from some light comedy, is to help people in trouble with their cars. You will mostly see people asking for help not threads about their engine running like the way it should.
Here's a lifter as listed by our friends at Jegs high performance
First time I came across them was in an '86 VW GTi - amazing idea - used to use one as a paperweight myself after doing a swap-out at 120,000 miles
Thanks Tippy - I checked their parts catalog for a decent picture first time around, but it was a generic lifter, and not a good shot at that,
didn't think to check the Pelican forum!
and variable lift) but not the standard M96 lifter. I dare say all hydraulic lifters work similarily and the interesting stuff's inside that housing.
I got to take some better pictures of the insides of an M96 engine lifter and post.
These zero-lash valve lifters are fantastic devices. We don't appreciate them enough I think. Well, as some who's done his share of valve adjustments I think I appreciate them.
Sincerely,
Macster.
So,
have any engines had issues with the lifters getting weak due to exessive wear from age? In other words the parts end up allowing the oil to leak out and thus not remain in contact with the valve (ie...ticking, like the old days with manal adjustments?)
second, Those dont look to hard to change, I am guessing there is a bit more to it than meets the eye with relation to the cam shafts/chains and timing... (I have never seen those exploded views or pictures)
And on another note.... I read up a few about a bad IMS bearing, What would one look for, listen for or have as a way of determining if the bearing needs replacing - then of coarse, how would you aproach that job.
AGAIN, I really am just interested in these things and NOT trying to pee all over the thread with stupid questions. My thoughts are more preventative maintenance. I think if some of these could be done in conjunction with other "normal" issues like replacing a clutch or something, it might be well worth the effort to do.... just ideas
As I mentioned above, I did a set of hydraulic lifters in a GTi, and this was specifically because they had become noisy.
Based on the assumption that increased noise indicated the lifters were no longer pumping-up onto the cam correctly - and that this would quickly translate into increased cam wear - I initiated a complete swap out.
Cam removal/refitting and timing settings were the key issues - the lifters themselves were pretty straight forward, they just needed priming with new oil before fitting.
The old lifters showed some scoring on the outsides - not excessive, but definitely there after the 100+ thousand miles of use.
Certainly far superior to the manual setting of days gone by!
VW GTi ??
I have done them on a Chevy 327, so far nothing on my P-car equates to those days except the little thing I use to inflate the tires with. The Cam and variocam (which I have no idea what is or does) frankly sound a bit scary to work on. (which might help explain why not many people have worked on them) The IMS is another WTF part for me and I hope to gain an understanding of it....(again, anyone who has had problems, had the motor replaced so there may not be much info on these areas.)
Not that your info isn't good, I just want to know about the M96
The pictures are great to look at and study, thanks to the OP!!!
Yep VW GTi - just using to illustrate what to listen for when hydraulic cams need replacing due to high mileage.
Maybe someone here can post M96 specifics.
OK I am going to shut up...... I just spent over an hour watching this guys vids on youtube. There are about 12+ vids each one is about 4 minutes. Here is what he did:
He had a bad Boxster, he rebuilt the motor, he video taped it. Made a lot of his own tools (obviously not an amature mechanic)
LINK (to one of the series)
So I know its not the same animal BUT there are some things I can see that cross over. I think the info is amazing and I see now what some of the parts are in the motor and how they are installed.
This is a cool look at the entire build of a motor - worth watching IMHO
Ed, thatnks for that link. His rebuild and documentation was awesome! I now know why these engines fail. It is because the chain guides are held in place with rubber bands.
I could do that, if I stay at a Holiday Inn Express for the next 6 years!
Yea, the one showing the chain assy is pretty hairy... and like you say, those rubber guides (not the bands LOL) have to wear (like he shows) and at some point must become less effective. Cheap and easy to replace as long as you already have the 6 years invested in a motel 6 !
I also liked the one that shows the upper end of the head assy with the lifters and cams going in, and the one where he is installing the wrist pins into the 4-5-6 cyliders, Thats some trick there too!!
Oh yea, and I see how "easy" it would be to replace/service
The thing that I have in the back of my mind is there is also "electronics" that have to interface with all these things... that's where I get triple lost !
getting weak (worn) and thus unable to maintain as much pressure and produce more valve clatter at least at startup. During engine running if a lifter noisy that's more than just wear.
These things fed from an oil passage fed by oil pump. They see high pressure oil all the time. The mating parts have some very nice sliding fits. By nice I mean given the diameter of the parts they fit together even with no oil so well that they have the abilty to even trap air and thus become an air spring. Assemble the two pieces together with no spring inside and I think you'd be hard pressed to separate the two without resorting to some method of gripping that would damage the parts. They fit together and slide very well.
My point is that it is hard to imagine a wear scenario that would see a zero lash device unable to retain sufficient oil pressure to function properly.
However, there's a check ball backed by a spring. Should this spring fail or the check ball develop a leak this would allow oil to flow out under pressure of the valve being opened and a noisy lifter the result.
The ball could develop a leak if a piece of debris got caught and prevented the ball from forming a good seal with seat.
Where would the debris come from? It would have to have entered the oil passage after the filter which is unlikely except in the case of a new engine.
More likely if the engine has some miles on it from dirty oil that is not going through the filter because the filter is full/plugged and the bypass valve is open allowing unfiltered oil from the pump to flow directly to all bearing interfaces.
The noise can of course come from another area. One possibilty is the lifter and cam lobe interface starts to wear. The zero-lash adjusters can only deal with a relatively small amount of lash take up.
Another possibilty is the lifter in its alumum bore wears the bore and the clearance becomes too great and oil flow and pressure that would otherwise flow to the zero lash device in the lifter housing instead follow a less restrictive path, the zero lash device becomes noisy at least under low oil pressure conditions because it has insufficient oil pressure to keep it pumped up against the normal bleed down that occurs during operation or after extended periods of no use.
The lifters can be changed. Whether it can be done with the engine in the car I don't know but I suspect not. Alot of dissassembly has to be done to expose the lifters. They live under the camshafts and to remove these requires removing the chains and this requires removing front and rear engine covers and well a change in lifters in the M96 not a quick or easy job.
For IMS bearing failure symptoms I know of no real advanced warning barring something turning up in the oil.
The transistion from a properly functioning IMS bearing to one that is not functioning properly is a very quick event. Seconds if that. If there is an advanced warning one may not have time to react to it before it is too late.
I know of at least one owner who detected something amiss and shut off the engine and apparently this limited the collateral damage and the engine was torn down and deemed rebuildable. I have pictures of this engine apart. I do not know the details of what the owner heard, what signal/sign he got other than something the mechanic said about noise. Probably just some horrible sounding noise that would make a person so alarmed as to shut the engine off first then think about the noise. Or better yet, not think but simply have the car flat bedded -- with no engine start/running -- to dealer for diagnosis.
As for preventative maintenance all I have to go by is my experience with an 02 Boxster with nearly 214,000 miles on its and its original engine. Frequent oil/filter services.
Mr. Raby does not like Mobil 1. He has covered this and I won't arque with him. There very well could be something about Mobil 1 oil that contributes to IMS failures and maybe other internal engine problems as well.
However, based on my experience with Mobil 1 oil it has served me and my engine well. I have used Mobil 1 mainly 0W-40 but sometimes 15w-50 and even 10w-40 exclusively since buying the car new. I do change the oil every 5000 miles along with the filter. Additionally I treated the engine to an early oil/filter service at either 1000 or 2000 miles, then again when the odometer read 5000 miles and every 5000 miles after.
Even at this stage of my Boxster ownership I'd change oil brands if I knew what to change to. But I don't and I am not in a position to buy an engine from Mr. Raby or have him redo mine in order to learn the better oil he has found.
Sincerely,
Macster.
The composition of the cylinder material also might be a cause of the cracking, I read about it in the 996 essential companion and as I remember the process is new.
though. I've seen pictures of broken cylinders and the material exposed looks more like ceramic than aluminum.
Could be the cylinder material. I've never heard of cast iron cylinders cracking although most iron block engines used a closed deck which supports the upper cylinder wall better.
Sincerely,
Macster.
True, but have you ever cut cast iron drain pipe? All it takes a a score line and then it snaps like how one would cut a piece of glass...
I dont know what materials we have, but I just brough this up
doesn't bother with any heat treatment to reduce stress in the casting. The stuff's cheap and once buried or in place is not likely to crack in spite of its brittleness.
Engine blocks are a different iron and have received some heat treatment to reduce internal stresses. Also, machining works to remove these as well.
I don't necessarily disagree with your point about the composition of the M96 engine cylinders being a contributor maybe the sole contributor to the cracked cylinders.
Any casting process can introduce stresses or weak points from inclusions of some contaminate. The cylinder is actually a rather porous insert with a high content of silicon that is fitted into the engine block mold and then during the casting process molten aluminum flows into this insert. If the insert is banged around during shipment, assembly, etc., it could have a crack that will cause it to fail later when the engine's in service. We do not have access to the Porsche factory failure analysis of the engines that fail so we don't know how big (or small) a percentage of early engine troubles/failures arise from this area.
Until something is clearly identified as the cause just about anything is suspect.
Sincerely,
Macster.
Any cylinder can fail... We have seen more outboard cylinder failures than center cylinder failures...
We are just starting to gather enough trend data to make accurate hypothesis about whats occuring and why... It takes direct interface with a high number of failed engines to see this and prior to our program the factory was seeing the engines so things were swept under the carpet.
More effort has gone into why and how things fail than anything.. The solutions to the issues only required money to create and thats the easy part coupled to somne intense motivation, dedication and application.
