If you think IMS bearing failures are all myth, then check this out...

This is a car that I bought last year from a fellow who took it to a local Porsche shop here with some odd sounds when running. The car ran and drove, but every few seconds, it would create a loud screeching noise and other associated weird noises. I bought the car for $10K from this fellow, as it was headed to LA Porsche dismantlers if I didn't buy it. The car drove and appeared to run okay, but kept making these noises, particularly on startup. Sometimes it ran perfectly quiet, sometimes not. The car is a 1999 Porsche 996 Carrera 3.4 engine with only 31,000 miles on it. Today, we took the IMS cover off of the engine to see what was underneath. Check out what we found: The entire bearing has been destroyed. The seal is nowhere in sight, and the race came out stuck to the bearing cover (which was scratched and damaged). Apparently the balls were just floating around inside and it was only a matter of minutes before before the motor lost timing and grenaded. You can often detect a problem like this by plugging in the PST-2 (or Durametric) computer into the car and then checking camshaft deviation. This car will be saved, as I think we got to it in time. As mentioned previously, we have a new prototype intermediate shaft bearing replacement kit that we are working on, and we'll be installing it on this engine for testing. This will all be detailed in a very lengthy tech article that I'm working on right now. Enjoy! -Wayne

Yikes! Suspect the oil pump is also trashed due to axial runout on the gear end of the intermediate shaft.

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I'll have to think about that one. There's a tab that turns the oil pump, but the shaft is secured on the opposite end as well... -Wayne

funny, i pulled my IMS bearing out and it looked like new. from my 2000 996 w/ 97k

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I was thinking that if the destroyed bearing was allowing the flywheel end of the intermediate shaft to wobble around, that would probably destroy the bearing surface on the other end of the intermediate shaft - and that bearing surface is part of the oil pump.

Maybe. I'll have to consult my torn-apart engine for more info... -Wayne

Thank you for the info Wayne I am hoping / assumed the startup squeal on my '99 was a starter bearing. It doesn't happen often. and my records that came with the car say the engine was replaced at 21,000 miles in Feb 01. Opinions? I was thinking with a replacement engine I had a starter to worry about not the IMS Looking forward to the 996 book.

I just bought a 2000 996 which had its engine changed under warranty in 2002 at 8K miles. The car now has 23K miles and runs great, but is there a way to tell whether this engine is susceptible to this kind of problem?

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That squeal on startup typically indicates failure of the starter - it stays engaged after the engine starts. It'll get worse until it does it every time you start the car. Starters are relatively inexpensive, and easy to change as a DIY.

IMS problems can sometimes be spotted through camshaft deviation measurements with the Durametric tool or the PST2. I have an article coming out on this very soon (Monday maybe?) -Wayne

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I'm waiting I downloaded the beta software durametric has since their site says you can run both. I didn't know it would be strange trying to figure out how to load one or the other. The old desktop icon loads the old version while it seems the durametric program under programs starts the beta. Anyway the beta so far doesn't seem as detailed as the regular program for cams. Please include in your story actual screen grabs and data exported to excel so I'll know what I'm looking at. A guy on another forum was posting deviation numbers for bank one and two while I am not seeing anything but one deviation for my 1999 using the software. Oh well possibly its a vario cam plus thing. At least this car is the same year and I should find out if my software is lacking. Looking forward to your story on spotting IMS problems with the Durametric. Thanks.

My 996 mechanic informed me yesterday that the slight engine vibration and cam shaft deviations of my 2000 996 indicate a potential IMS bearing failure, and that I should not drive her until I have this replaced. She has 77K miles and has been properly maintained and never tracked. After reading this thread (and staying up all night in dismay) I am assuming this is good advice and I should go through with the preventative repair? Thanks in advance for comments Lauren

I replaced my clutch and had a LN Engineering ceramic IMS bearing installed at 45K miles on my 2003 C2. The total cost was less than $2.5K and I can now sleep well at night. Money well spent, IMHO. BTW, the old IMS bearing looked fine, but had a bit of a bind to it when hand turned.

Thanks for the input 88carrera. I have scheduled the replacement and also plan to have the clutch disc and oil separator/oil tube replaced at the same time. Clutch is fine as it was replaced after it started to go returning from Rennsport III 4 years ago. LOL. What next? I think I will be happy to have the ceramic bearing from LN installed and have the peace of mind you spoke of. Cheers. Lauren

I just had the LN Engineering IMS replacement bearing installed by Joe at Series 9 in Deland, FL. Clutch, pressure plate, throwout bearing, RMS, AOS, and oil and filter for $2,700 out the door. Car had just turned 100,000 miles, IMS bearing appears good, clutch was worn but not worn out. All parts virgin. Looking forward to the next 100,000.

LarryHughes, Good to hear this. I am now at 55K miles and sleeping very well. It is good to put to rest all of the garbage out there about our 996s being hand grenades. Love mine and trust it to get me where I want to go. It has not failed me. I also did do a preemptive water pump replacement just to be sure. Keep the faith!

I dropped '01 off at the shop on Monday. 68K miles. I've been driving with my fingers crossed since I got the car 6 months ago.

We have changed quite a few bearings during clutch installs for clients, yet to see a bad one. That said, some will prematurely fail for sure, but there is much hype with these. All Porsche engines have had issues.... If the internet was around in the 70's and 80's imagine how bad the stories of head studs and valve guide wear would have been...

Just in time!

I agree with Jeff. The old style camshaft chain tensioners (in air cooled cars) would fail with destructive results, the same as the IMS bearing. Porsche redesigned the system with pressure fed tensioners and failures went down. There are a number of remedies to this problem. You choose the one that works best for you and then monitor it every time you change oil.

I was checking the oil filter when I changed it. I didn't see any signs of a problem. There was nothing in the oil to give me any indication there was a problem.