Rebuild?

Driving today, no overrevs, always drive hard. I do take care of my 911, however. As I'm driving, I hear an odd change in the exhaust note next to the guardrail. I checked gauges and oil pressure is low. I just replaced the alternator week before, but at this point I did not check voltage. At the very last maybe 5 seconds before I turn the key off to shut the motor down at 65 70 miles an hour, I check oil pressure once again. It's between two and three bar. This whole process took about 20 to 30 seconds. I pull off side of the road and the car will not restart. Nor did I really push it hard to restart as I did not want to do internal damage. After getting the car home, my brother and I inspected and had to jump the car as the car would not restart from a voltage point. I was hoping that the alternator was the issue and that maybe that caused the engine to be running on the battery too long. However, after restarting, valve train is very loud and it sounds like a valve is hitting the piston. See the video, let me know what you think. Been looking at engine rebuild kits considering what I should do. I can do the rebuild myself, but not sure what's needed until I get the heads off. Anyone has any suggestions or rebuild kit suggestions as well, please let me know.

SBC LS3 crate engine with cam, 480 hp.

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What? You shut the motor down at 65-70 miles an hour? Then the car will not restart? Hmmmm....are you smoking weed? Everything you describe is non-sensical...meaning crazy. Yes indeed,disassemble your engine because it now is broken. That makes sense. Ummm...and there is no video.... Please tell me where you found a rebuild kit...I would love to know what is included in a "rebuild kit". Thanks.

Drain the oil, inspect the filter.

Drain the oil, pull the pan and see what's in there. There are no rebuild kits that I know of, you will need to buy the parts needed individually or at least that's what I did.

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Voice to text at midnight mate. Ran car very hard, but no over revving. Had the car 3 years with an AOS, starter as well as charging cable and alternator the only changes. While driving, I heard a change in the exhaust note. Checked gauges, lower oil pressure. No smoke from pipes. Yes, shutting the car down at 65-70 to keep what's left of internals. Smarter than trying to keep it running. So no idea what you're missing there. Weed? Yeah, okay buddy. Rebuild kits. Plenty around. LN engineering has a kit, or there are basic ones without too much hardware. https://lnengineering.com/m96-03-eng...r-premium.html Video, the YouTube wouldn't attach which I will try again here or from my PC later. Link is this: You Tube If you want to be a ****, which it sounds like you are, than you can go and eff off and why waste your time. Looking for some assistance as to next course of action based on the situation explained. I've seen these motors be fine with similar sounds. I've seen them need rebuilds with the same sounds. I plan to pull the pan or at least the filter and check for debris. But, again, asking for similar experiences what your course of action was. Regardless, thanks in advance.

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I would NOT start that again until you do some looking around.

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Correct. Based on what I hear and past experiences with a non-flat six, pistons and valves plus heads. It just sounds like a valve. I have not torn down a 911 motor before, but not scared to do it either.

Sorry to hear about this. Something all of us hope to never go through. Sounds like you just shut the car off at speed and let it coast in neutral and stop safely - nothing wrong with that and smart move. When was the last oil change btw? Have you noticed any leaks or seepage on the motor? Please post photos when you drop the pan and open the filter.

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Absolutely. You do not want a motor running regardless of what you are doing with possible internal damage on tap. Anyway, thanks for the message haha. Last oil change was 5k almost to the mile. I use 0W40 Mobil 1 as always. No seepage, no leaks, good coolant, good oil levels etc. I will certainly make a decision of what to do on the rebuild, assuming that is what it needs. I def will put a 3.6 back in rather than a swap. IMS was done at 76k as well as clutch right before I purchased a few years ago. I now just turned 110k.

That sounds like a bad piston slap. Pull the oil pan, inspect for debris and borescope from under the pistons. Possible d-chunk from the bottom of the cylinder?

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If you decide to rebuild it yourself, I'd go 3.8 or 4.0 Nickies since the costs are the same, except for maybe the head gasket cost.

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you should try it might make you less of an abrasive *****. probably not though. @Clockel got a link to the LN kit?

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OP, is this the car in question? 2002 C2? The one you complained about having excessive oil consumption? The sound in the video is similar to piston slap. Therefore, you'll want to watch Jake Raby's videos on the subject. This engine sounds done to me. You Tube

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Fact. Yes, I posted it near the video link.

@b3freak Yes, same motor. It appears that the AOS replacement was much of the consumption before. But, the bore scoring has been in my head since I have owned the car, and I assume is culprit here as well. Yes, I will watch those videos, seem on point. I agree that this is piston slap, but not knowing the internals as much as other motors, maybe a broken valve spring and the valve is coming in contact. Pretty light rod knock if that is the case. Most times a rod knock has deeper sound and much worse. This sounds higher, i.e., piston into a valve. Anyway, couple of things to look at first then will make decisions. But yes, lol, sounds like a done motor to me as well.

Sounds bad to me. Good that you shut it down right away, although starting it again could have been catastrophic. But doesn't sound like piston slap to me. I believe D-chuck would prevent it from running at all. Definitely drop the sump and take a look. Borescope from above, because if it's got THAT bad of piston slap I'd suspect you have bore scoring visible from above. If nothing, then borescope from below. If all looks ok there, then drop the engine and open the valve covers and take a look.

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Proper. I agree to some extent as well. And, re starting was to hear the sound......probably doing damage...fml, which I know. Annoyed with myself at many fronts. Anyway...scoping is next with the pan drop. Deciding whether to have my quality indy do all of this or rebuild myself.

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Good thinking! You know what to do. Remember, rod knock will change in pitch and timing as the RPMs increase and decrease. It's a horrible, deeper sound, no doubt about it.

Sounds like a "roasted rod bearing" to me. Failed rod bearings can have two distinct "sounds" on M96/7 engines. It can be a deep low tone from the slack in the big end of the rod, OR it can be a higher pitch lighter tapping sound from the piston hitting the head. (very close clearance from the piston top to the head) It can also be a combination of both deep low tone and higher pitch lighter tapping sound all at the same time or changing up some. But will always be the same cadence/frequency (ie once per revolution) Your low oil pressure scenario pretty much nails it to rod bearing failure, dropping the pan will confirm..

@PorscheTech3 that is an interesting observation about the sound. I'm no Porsche Tech but all the engines I've ever seen with a failed rod / bearing had the low tone knock sound you mention. You may want to pop over to the 986 Forum too, as a member there has this sound and I'm pretty sure it is a rod. I could see where the piston smacking the head and valve would have a different sound though. To me this one is a higher pitch click, which I've always experienced on other engines as a valve train issue.

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Absolutely. Facts here.

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This is fantastic. Haha, people are such d-bags with no reason. Though, I admit, my post was not the best either.

I apologize for my post. I read your post and really did not understand what happened. You appear to have some great knowledge regarding the 996 engine, and what you did now appears totally logical. Really hoping it turns out okay. Please accept my apology for not understanding. I hope you keep us apprised as to the problem(s) and repairs.

Not sure that sounds like bore scoring to me. I do know my car never made that noise and it was at a stage 4 (maybe 4+) when it was torn down.

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Not a problem mate, apology more than accepted. Thanks for the message. My post was not truly very well stated, so I do agree with you to some degree. Yeah, no worries. I will drop the pan and inspect, pop open the filter as well, and I will certainly have a rebuild thread following. I am now interested in which kits people have used and why, whether to sleeve it or buy another case(s), etc.

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First pull the pan and then go from there. If you spun a bearing, among everything else, you will also need a replacement crankshaft and carrier. There is no point speculating any further, time to get your hands dirty.

No question @Imo000 , at this point it is finding the space. Garage space just got limited prior to this hiccup.

Its nice when we play nice. I think Porschetech3 is onto something with the combination of knocking and low oil pressure.

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You are correct in that "most " rod bearing failures on common engines have that deep knock sound, but M96/7 engines have a really tight clearance from the piston crown to the head quench area. So much so that any carbon build-up in the piston crown of over 1mm can also lead to a sound like "piston slap".. Case in point a Rennlister here (3/98 911 Coupe ) had a knock that everyone assumed was a bore-score/piston-slap, I suggested he do a de-carbon of the pistons and TexSquirrel did it ( thread in here for some if interested) and it totally stopped the knock. I went over to the 986 forum and looked/listened to the video/audio, that engine with only 5 psi oil pressure and that sound for sure has a failed rod bearing.

the low pressure could be from the "0" weight oil it could be you dropped a valve seat, that could esplane the different exhaust note you mentioned prior to shutting it down scope it from the spark plug holes and see what's in there

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Interesting you say that. I was wondering the same. I have a rocket scientist coming this week to have a listen, he builds race motors for a living, so he thinks it is more valve train than "bottom" end. But yes, both the pan and boroscope are planned. Thanks!

Could be a " loose spark plug" too !! That's the fun thing about diagnosing cars on the " Internet" !!!

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Oh. My. Good. lordie. I always laugh about this shat. Haha, can never tell till my dumbass climbs under the thing with some fingers and inspects. So true.

Update finally. Took to my local Porsche stealership to confirm or deny what I already knew as I have been busy with work. Confirmed there is metal in the filter. So, decided to buy a low mileage running motor. Will be updating as I do the swap. Will be adding a clutch and a gearbox flush as well. My quote is quite hilarious, for the record. $25860 for a motor from Porsche. Life is good. Will add pics etc when I begin. Additionally, as some of you know and comment, I am going to get rid of the 0W40 and begin running much thicker. 15W 50 as recommended by my tech and Porsche classic for the car. Recommendations gladly accepted.

At that price just have your motor rebuilt and not have to worry about the new used one doing the same in the future plus your current engine can gain some performance Mike

Yes sir, obviously I am not buying that motor. In Denver, we have only one guy that can properly machine the casings and heads. Thus, I am going to part motor out based on condition and just slap an IMS into the low mileage motor. At the cost of less than $15k, I would rather buy that and do minor work on it than rebuild mine shipping and waiting for everything from LNEngineering.

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70 percent of wear happens at startup. Your oil is in the sump. If you want to change the brand etc and run something a little more viscous try a 5w40 or if you can find it a 5w50 (make sure oil has Porsche A40 approval). If you are looking at a 5W40 look at the tech data sheet. The Mobil 1 0w40 has a kin visc of 12.9 at 100. If you find an oil with 14.5 that should be good enough. I�m using 0w40 and based on what I know that�s the best for me , I�m a retired tribologist (lubrication engineer). Best of luck to you.

Update. Bought a motor, doing IMS and a clutch and some other minor needs. Motor had 39k on clock, needs a couple small things. One owner. Decided against a rebuild, unless the cases are salvageable. Will be strapping new motor back in this weekend. IF anyone needs parts off my old one, I will post in marketplace.

Bought a 39k mile motor out of GA. Excellent shape. Has original IMS and clutch, which will be replaced shortly. Also blew out the damn slave, so that is getting replaced as well. Other than that, all is going well on this swap.

Hopefully your luckier 2nd time around best of luck

They sure sprayed down that engine with Armora All. You can just put the slave cylinder back together and bleed it. That's what I did when mine blew apart during engine install. To save yourself a headache, install the slave before the engine/transmission goes into the car.

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The cheapest motor you can buy, could very well be the most expensive to own... Caveat emptor... Seems like you're in a rush. I think the best advice is to slow down and do some serious research - there are lots of options, but all the good ones take some time...

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I hear ya, but you are incorrect. Car has been torn down for 3 months. I have done extensive research into everything from building a 3.8 to swapping an LS. Been a mechanic for years. This has the best option with changes to already proven cases to a low mileage unit with good internals. Scoped etc. Thus, throughout the thought, planning, financials, etc, this is a slow process turned into an easy swap, if you know what you are doing. My serious research on top of what I already knew did me some good. Lot's of options? I disagree. There are not LOTS of options. Very few in fact. 3.8 build, rebuild, LS swap, or just put another running unit in with the correct structure. These cars are very niche when it comes to motors. Again, 3 months of work, research and planning. Thanks regardless.

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Not at all. Though, when I saw the imagery, I thought the same. Again, the car was 39k from new. Only AOS had been done. They are a Porsche transmission shop so they kept the gearbox. Was a decent buy and with an IMS and a new clutch will be a good unit I think. And for the record, Armor all sucks.

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Thanks mate, much appreciated. $12,000 less in the accounts means I hope for better luck as well. Haha.

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Good luck on your swap. Are planning any replacement parts or enhancements to the engine before you drop it into your car?

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Not other than IMS and the clutch/slave. Considered port and polish as well as exhaust, but really, these motors are so temperamental that I am choosing to do the necessary items. I inspected the IMS, it is the original part number, though, it is in great shape with no weeping. Regardless, I do not want to be a part of the 5-8% of failures. Period. haha. The motor is actually already in, running, and I will drive it about 3-5k before pulling gearbox to do both the aforementioned. I wanted to make sure it runs as expected as I do not have an engine stand to run it on. Thanks a ton on the support mate, much appreciated. It really is a simple swap. Simple.

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The more I talk to Porsche guys, attend events, etc, etc, I keep finding these smaller race shops that rebuild the engines. Interestingly most of them don�t advertise and prefer the word of mouth endorsement. I continue building my directory.

Solid work...I like the "getter done" types !!

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Absolutely. Cogs is renowned in GA for quality Porsche transmissions, buddy has used them before.

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Thanks mate. Yes, if you can turn a wrench, you can do a swap in this car. They are truly very basic, on the "outside." I hope it helps others to be inspired to do their own in the future.

Welp, new clutch in today and stabbed the gearbox. She runs and moves. Couple minor things to finish up.

Had a couple DM's about the car. So I decided to post up on current status. Car is running well, have driven it about 5k miles. The 40k motor I put in has been running well as well as the new clutch. I have been using 5w-50 synthetic on this motor, I still feel the 0-40 is too thin. Overall, motor swap was relatively simple, straight forward, and not as time consuming as some might expect. Some updated shots below. I plan to pull the motor again this spring to do the IMS bearing as I was struggling to get parts in time previous round.

Thanks for the update. Gotta love engine swaps in the driveway with some jack stands and some hand tools The stance on those wheels looks absolutely perfect! Well done.

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Thanks man. I did tons and tons of measuring and research to make sure they were perfect. And yes, jack stands and motor swaps are far from my favorite idea. But, these are for 3500 HD trucks haha.

Quick update to the rebuild..... Well, motor in for 20 months now. No issues thus far with about 15000 added to the clock nearly. Just did new set of tyres and some aero bits started. The front splitter is all fabricated mounts, by me of course, an APR carbon splitter and an APR GT rear wing. The wing is still in fabrication state as I am modding a secondary deck lid to accommodate the APR uprights while also building chassis-mount uprights. Splitter gets glitter water paint for downforce info and correct air flow. That is all being advised upon by a nasa fabricator, but it has come out well thus far. I have yet to see a 996 with "proper" aero. It is rare. Normally you see the typical GT3 bumper or aero front spoiler, that is about it. So this project has had zero influence by any build yet. Regardless, some build shots, mock up shots, and current status. I may trim the outer edges for the splitter. In addition, widebody RSR kit is on the docket for later in year. Obviously more than just a bolt on and run kit requiring new wheels, tyres, and of course bodywork.

If you really want the splitter to put in work, get some tunnels in it. I like the way you mounted it though. Not sure why you wouldn’t just go path of least resistance on rear wing and go with a cup based setup. If you wanted something with a more aggressive foil, you can go custom from a number of wind tunnel tested companies or Voltex makes a couple spicy versions that can bolt to cup uprights. Alternatively if custom is what you’re after, a swan neck would likely be worth the effort with a really good foil. ETA - if you want the contact of the best person to reach out to for your future WB plans let me know.

Thanks zbomb. I have definitely followed a bit of your stuff. Yes, the work load would be less, but with my buddies direction on stuff, and what I already own, I think it will be good. He is stating a lot of the cup stuff is lowering in height over the years (he builds a lot of cages for nasa porsche's along with time attack Subaru stuff) and the route I am going is proper for the parts I have. I did end up buying both parts from him actually. He'll be printing the wing risers from the uprights for me. As for the splitter yes, it worked out great. The piece has a place to go and compress but is solidified with 6 points including the original bumper mounts. They have an additional tack or two as a result as well. I am using adjustable splitter rods in the next week or so as well. Thanks for the contact on that, I will attempt the secondary deck lid that is black and off a similar car, and see what is what. I am always open and interested in further contacts on this stuff; so, thank you. The RSR body stuff is crucial. I have signed up for it already, I am too deep in this car. Stay posted.

Update to the build. Well, new stuff. Half second late on choice into intersection and he braked suddenly. My mistake and choosing to crack into the Saturn in front of me... Regardless, new hood, bumper cover and crossmember + latch is what is needed. Luckily, car low enough it is mostly cosmetic minus pulling out the crossmember. New bumper cover ordered, needed one anyway. Paint was also wanted on the hood and cover, so I am actually not too upset. Ig anyone has a hook on hoods, black or Arctic silver preferably, that would be great.

Hey at least the splitter and headlights didn't get damaged...minor fix and you will getter done in no time !! Glad everything is going strong !!

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Cheers man. Much appreciated. Just one of those things. Will come back uglier but better haha.

Hey I have a carbon fiber hood I’d sell but shipping would be a biatch

@EVOMMM Yeah, I would be interested, but shipping would be foam under wrapping and probably palette based. So yes, $250 is what I am seeing. PITA. Shoot me a DM and we see what is what. I am having trouble finding a hood nearby, so shipping may be it.

Well, been a while since I have posted. I have been flogging my 996 since 2021 when I swapped motors with a 39k mile unit. Car has been pretty solid overall. I had put in a new clutch, slave, new oil in gearbox, oil cooler, Cup motor mounts, titanium exhaust, and a couple ignition coils. Well, now a few years later and another 36k on the motor, the rear main seal has gotten so leaky that it has ruined the clutch and when it began slipping a few months ago I knew it was time to do all the bits. I have gotten closer to getting all the aero bits completed as well while ruining a couple carbon APR splitters in process. I am now working on bonding the wood and carbon splitter to get more strength and rigidity without cracking the carbon ones. The car won't get over about 120 without a fair bit of nose pull. I am building the aero with approximately 100 being the sweet spot. I have never really cared about the max, although I have hit 159 in this car more than a few years ago. Most of the roads I drive are mid speed mountain ones here in the Rockies. New bits ss follows: - New LuK flywheel (factory as I did not want to do all the spacing bits and lose the drivability) - New Sachs Clutch (the stage 2 kit with stiffer flex plate) - New rear main - New IMS bearing (while I am in there...) - New gearbox mount up front (been also loose for a bit, although I did put a bandaid on it a year ago) - New front Bilstein B8 struts (rears to follow ASAP) - New spark plugs - New hardware for all new parts - New CV shafts (the good ones) - Not new, but the TeachArt Carbon front bumper will most likely go on before paint in a few months. It requires some repair. I think that is it. So I pulled the motor and gearbox last night after the office. Came out easily as last time. But....this is by far the dirtiest motor I have seen in a while. That leaky rear main has caused buildup all over. And I am over it. I plan to degrease and clean up the motor and box as best I can. We shall see how far I get on this. I figured I would post up and let you all know that she is going strong overall. Cheers.

Just for a refference i get to 145ish every lap at watkins glen with this front end and have zero instability. Rsr chimney, Joe Thoth canards, gt3 liners and a demonspeed cup splitter

You'll be really happy you cleaned everything once you're done, and it will look great.

It is a dirty bit of mechanical crap.

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Heck yeah. I am stoked to have it clean again. Dirty is so bad on these cars with all the orifices on the chassis. I will post updates as they come along. Any suggestions on how to clean the muck off the gearbox and motor without destroying things?

Long overdue on the rear main, as can be seen by the immense amount of grit buildup, but.... Put in a rear main, IMS bearing, Clutch, Flywheel, gearbox mount, CV shafts, oil change, front Bilstein B8 performance struts. The IMS was in good and smooth shape, I have 75k on this motor. The process was not too bad, this is the first IMS I have actually done. I will say that most of the buildup is rear main as well as cam cover seals. They had been punctured before and looks like some oil was building up from them dripping down to the exhaust. I also inspected the cam covers for leakage and had thought that was additional culprit to the rear main. On top of all that, updated the Cup mounts to the middle stiffness setting and am working on the roll cage and seat updates. More to come on that in the coming weeks. Cheers.

A good time to install the UAOS Track System ....