Datura

'06 Carrera S, some moderate tracking, 58K, has had zero mechanical issues along the way.

gla

07 Carrera S 15K perfect

MLindgren

I have a 2005 C2S with VIN number WP0AB29925S742410

I am having my clutch replaced and had asked to install the LNE retrofit bearing. I was just told that my car has the 2006 style bearing and they recommend not splitting the case to do the bearing. Based on the lack of failures on 2006 and later I have to agree. It would be interesting if we could gather data and narrow down when the changeover happened.

On another note my clutch failed due to the pressure plate fingers on one side bent back causing the clutch to only engage one side of the flywheel.

red carrera

I listed the issue in another thread too, but the '06 RMS & IMS both were found to be leaking during the annual service mid October at 24k miles.

Dealer replaced RMS and IMS seal cap and offered to split the cost with me. I thought it was fair.

gpjli2

This might be more meaningful if it isolated the reported 05 failures and computed reported failure rates separately for 05's and 06-08 cars. This would highlight what we already know: 05's have a significant issue. They also have for the most part a easily (relatively) replaceable bearing. Sorry to state the obvious but there have been a # of posts from 05 owners that don't seem too sure what to think about this.

997_rich

the original post asks for which year you drive when you claim failure. Not everyone has been doing that but if you look back at all the people who claimed failure in this posting it's something like 65 or 70% 2005 failures. Surprisingly there ARE a few 06-on failures.

We can assume most 05s are m95 engines and most 06s are m97 engines but that's not always the case. A few late 05s got M97 engines and a few cars that are 06-on actually might be 05 cars that were sold for the first time to a customer in 06 getting 06 on the title.

997_rich

Many have been asking to understand how many of the 997 cars have had IMS (intermediate shaft) failures. Please post only IMS failures (not IMS seal failures or RMS seal failures, these are not catastrophic). Although the people on this board are not necessarilly a random sampling of 997 owners I would like to see a poll to get a better sense of it.

Please vote only once for each 997 you own (yes or no).. you can post multiple times but only vote once
Please include details of your car and engine if it failed via IMS (m96 or M97) and when.
Please let us know if there were any mitigating factors (low oil, overheat, etc) that might've led to the failure
Please post only about IMS failures, this is not about RMS failures or IMS seal failures.
Please post only for your car, no heresay or posting for a friend who doesn't frequent the board
Please post what was done to rectify the failure if your car failed (CPO engine, engine out of pocket, used engine, sold, insurance fire, pushed it into a river etc)
Hopefully this will help owners and soon-to-be owners get a sense of how frequently this occurs.

*Thanks*

odurandina

i just voted so i could see the results.

mod. please strike out my yes vote. 997 guys, please accept my appologies for voting.

911SLOW

1 vote removed

simsgw

No problems of either sort. Or any other sort for that matter. 2009 C2S with 29,500 miles. I wasn't even tempted to violate that last stricture because the only acquaintance with a failure ascribed to IMS was running a 2005 with aftermarket forced induction. And from his stories at least, he liked to use all that extra power, so his experience would be what we call a "wild point" in formal statistics.

Gary

Gas Passer

My CPOed '07 S with 41K had weeping RMS replaced and they went ahead and replaced IMS as well under warranty. Stated IMS was fine, but dealer states they replace due to the easy access. No other issues but O2 sensor which failed 6 months ago. Dealer was happy to report 80% life left on clutch. Glad no abuse from previous owners, got her with 22K almost 2 years ago.

MLindgren

Are you saying that you think a leftover 2005 that is sold in 2006 is sold as a 2006?

gpjli2

Ok. now, I don't get this. To replace the IMS in an 07 you have to split the engine cases. The bearing is larger than the hole in the case. Easy access this is not. A MAJOR undertaking not to be done just because you are fixing an rms leak. Either the dealer was blowing smoke up your a$$ or there is a misunderstanding. Either way enjoy your great car. '07's very rarely have ims problems. I would find a different dealer for service though unless you enjoy being lied to.

gpjli2

Don't think so. Late manufacture 05's can have the updated bearing. You really have to look to be sure.

simsgw

I just took time to read the answers in detail and realize we owners of 997.2 models had been asked to not vote, since we don't have an intermediate shaft. Should have realized that for myself. Sorry, folks.

Speaking as a professional, I have to say first that I agree with the comments from WinkingChef back in April that our venue and the procedure both skew the poll heavily toward exaggerating the problem.

Since that is the case, the results say the notions about a class-action lawsuit are so much froth. Understandable froth, if it's forming around the mouth of an owner whose engine has failed, but still foam with no substance. With no statistical support for a negative result, we nevertheless have pretty good results in Porsche's favor. Consider:

1. The number of 997.2 owners who voted when they should not, like myself, looks pretty low. I don't feel like re-reading everything to do a tally, but it was surely less than thirty of us. That leaves about 200 owners of the 997.1 that have had no problem with their IMS.
   
2. The number of people who reported an actual failure within the poll's intent was quite low. Under ten it seemed, though the 'yes' tally is higher because of false reporting in the other direction. (That is, non-IMS failures.) Even using a method that skews the result badly, the problem is reported for less than five percent of cars we owners consider to be "at risk." Which suggests we're wrong, except in the rather useless sense that men are "at risk" of prostate cancer and women are not. Clearly, the IMS bearing cannot fail if you don't have an IMS, but we needed no poll to tell us that. You can avoid all risk of engine problems if you simply stick to a soapbox racer.
   
3. I didn't see my acquaintance's name here (he who blamed the IMS for a modified engine failing that already had lived a lot longer than would have been my personal expectation). But I did notice at least one that denied abuse in terms that actually admitted abuse. Like the case of an engine with aftermarket induction, Porsche would be justified in refusing any warranty claim for the direct power path of an engine with the DME print-out that particular yes-voting owner reported. (He said: "Nothing in ranges five or six, and not much in four" -- which is a self-admission of serious abuse. Revealing, though not to be confused with a serious admission of self-abuse.)
   
4. That case, and my acquaintance as well, were cars well past the time limits on the warranty in any case. As we'll see below, for technical reasons this problem is more likely in cars with more time and fewer miles, so this is relevant. For all owners with cars within warranty, as far as I noticed, they report having had the dealer replace the IMS bearing in early-manufacture cars. And all the cars in warranty that failed first had their engine replaced by Porsche.

Bearings fail. Since the invention of the engine, load-bearing surfaces have been a critical and difficult design issue. I'm an aerospace engineer, not automotive, so I don't have numbers at the top of my head for this, but one of the two biggest factors in picking a red line has got to be bearing stress. (Valves are the other of course.) So manufacturers are justified in declining warranty claims on engine regularly operated above redline or with aftermarket changes that intentionally raise the bearing pressures to the same level at slower rotation levels. (In case, it isn't obvious, the whole point of forced induction is to raise the pressures inside the cylinders. That's where the additional torque arises. And cylinder pressures translate to bearing pressures. That's one of many reasons you have to lower the effective redline if you add forced induction to an engine.)

For those reasons, I'd expect to see a group of avid enthusiasts like us report one or two instances of bearing failure somewhere in the engine out of every hundred owners. Now as for the bearings supporting the intermediate shaft, let's consider that further.

From the article in Excellence magazine, the problem with the '05's as shipped was traced to some of the suppliers... (Or possibly all? I don't remember offhand. I read the article out of vague interest since I don't own a dot one.) Anyway, whether briefly universal or affecting only part of the manufacturing line, the IMS bearings in those early 997.1 cars used a bearing shell that was too aggressively lightened. It was made from an alloy in a wall thickness that permitted corrosion to make the casing porous. That is, engine oil could seep into the bearing case which dilutes the permanent grease and eventually thins it to the point that bearing surfaces contact each other at high loads. That eventually leads a bearing to fail. In other words, it takes corrosive fluids in the oil to start the process of weakening the case, and then it takes high loads to complete it. In fact, the latter applies to almost any Porsche, so if the first arises, then the second is sure to follow. Perhaps a little delayed in a car driven 'gently' but still inevitable once the wall of the casing begins to allow engine oil to seep into the bearing volume.

That description is my memory of another man's writing and probably he got it from another source who actually examined examples of failed bearings, but what I read sounded well-considered and I think I've done it justice in the retelling. It certainly is consistent with the wide impression that this problem is most likely in lightly driven cars, and also that it deserves the title of "an issue" only in the first year cars, those manufactured in 2005. Case wall corrosion can occur with any ball bearing of course, but to be perceived as "an issue" we'd have to see it in cars within the normal range of ownership, and I think low mileage has to be considered one of the more common modes of Porsche usage, even if Porsche recommends against garage queens. (For those who may not know, corrosive fluids build up in engines that are not operated regularly at power levels high enough to reach full working temp for the oil and coolant. Running at those temps evaporates the worst acid compounds and is an essential part of good care, along with changing oil sooner if you don't use the car as a daily driver.)

Again, our results are consistent also. We have most of the failures in '05 cars, and of the others, at least a couple I remember were cars that might well have been built in '05 although they register as later models. So what we have is a design choice at Porsche themselves (if it was all suppliers) or at some of the suppliers who deviated without being caught immediately. Porsche has corrected it in cars affected, but some of the owners who have a prostate gla... uh, an IMS feel they should have their engine changed anyway for their peace of mind.

I can understand those owners. My own prostate gives me pause occasionally, though it hasn't failed, but the maker also has declined replacement. Nevertheless, ball bearings can't be viewed as irresponsible design choices or all us engineers would be jailed. Nor is that intermediate shaft so supported a reason to complain. The use of intermediate shafts is another routine design technique.

What really comes of all this, adding in the technical article in Excellence, is:

• Owners of cars manufactured in 2005 (and you can look at the plaque in the door jamb) should make sure their car had the IMS bearing replaced if it is one of those with thin walls. If not, Porsche is likely to honor a request to replace it now, even if the car is beyond warranty, but do the work in any case. This is the group of cars that really is in the "at risk" category. Dealers have specific VIN numbers I believe.
  
• If you have added forced induction to one of those early cars, don't expect Porsche to replace that engine if it fails, in warranty or out. As a matter of fact, I eagerly await counter-examples, but I don't know of any manufacturer who would replace an engine so modified. That's one of the hidden costs of significant aftermarket mods. That is, those that actually produce serious horsepower gains, not just improved acoustics or similar benefits.
  
• For peace of mind, and because you never know what corrosion has been going on that deep in the engine, an owner of a 997.1 might want to consider the IMS bearings to be a life-limited part. Like the rotor in a helicopter, that means you should replace the part routinely after so much time or so many hours of operation. This is personal choice of course, even after the warranty period. You won't fall out of the sky, but a failing bearing in the valve-train destroys any engine that lets the valves and the cylinders occupy the same space at different times in their cycle of operation. That's called an interference design, and again it's quite common, but it makes expensive noises if the method of timing those movements fails. The IMS is part of that control for a 997.1 engine. A bearing case of the thicker design isn't going to fail while we speak, but it is reasonable to replace it after the first 50k miles I think.
• Run oil analysis at each change, and if you're really paranoid about this, step away from the computer and go install that sensor described in Excellence that looks for metal particles in the oil in real time. Now. What are you waiting for? Why stay paranoid when someone offers a pi.. uh, a solution?

Personally, I find these reports reassuring, given the acknowledged tendency to skew the results in the frightening direction. I occasionally think it would be nice to have a roadster around for those beautiful days in Spring and Fall. From this poll, it sounds like I could buy a 986 in confidence, and at worst I would want to put in the LN bearing if I'm worried about the previous life of the engine. Considering that the prices of a used Boxster are seriously tempting for such casual use, I may well buy one.

Thanks for the reports, guys.

Gary