Palmbeacher

According to them they've had five bearings fail, all of which were the small, single-race version. Without them revealing the exact number of this particular version that have been installed, it's obviously impossible to calculate an accurate percentage. And a huge variable is the fact that many shops, not to mention DIYers have done these retrofits, so there's a significant possibility some or all of the failures are related to knackered fitment.

The design of the IMS shaft and bearing placement makes it prone to failure. Beefing-up the bearing, whether that entails increasing the size (as Porsche did some time in mid-MY05) or using stronger materials (LN approach) can clearly reduce the probability of failure, but not eliminate it. That's the cold hard facts. From there it is up to the individual to decide how much import to place on the issue. As far as inspecting/replacing the bearing at intervals, in theory it makes sense, but as a practical matter it is a) expensive, b)no guarantee that bearing won't fail in-between intervals, and c) it's possible to replace a perfectly good bearing with a defective one or have it improperly fitted, leading to a failure.

rsabeebe

here's the real issue, though. let's say 1% of all M3 engines do fail (doubt it that's high) - is it from a single part? 996/997s are losing motors due to the same bearing and that seems to account for a VERY high percentage of all engine failures. again, i do realize this is [potentially] on a small scale, but it certainly doesn't give you any confidence when you think/know it could happen at any moment, without warning. if the cost of repairs weren't approaching $20k, it wouldn't be such a PITA. reality is, we're at half the value of the car when it does happen.

i had the 4.2 V8 in my B6 S4 Avant drop a valve at 40+K miles. total repair costs were $19k for a brand new engine from Audi. without the extended warranty that was on that car, I was looking at repairs of 75% of the value of the car. i don't know what makes more sense, an extended warranty on a 996/997 or to spend similar money (likely less for a sufficient term) and go the LN route and a new clutch.

i'm leaning towards doing the bearing. i was just curious of the success rate of the LN bearing and what they have suggested as the service life. maybe someone from LN will chime in.

rsabeebe

all good points, palm. as you mentioned, there are variables that go beyond the actual service life of the bearing, but it would be nice to know if the 5 failure are out of 100, 1000 or maybe more. of course, there could be more than just the 5 and none of them could have anything to do with the bearing itself. what a clusterf*ck!

i wonder what 993s are for sale today??

USMC_DS1

Had to replace the engine on my prior 98 m3 after an accident. SUV ran a red light n side swipe the front driver side hard... engine block cracked they believe due to overheating. $12k in parts/labor to replace but covered by the other guys insurance. Not $20k like Porsche but still up there...

I'm starting to think that the IMS bearing is the scape goat for engine's imploding on the 06-08 motors. A recent article notes that there are zero IMS bearing related motor failures, however, we have seen postings of forum members indicating otherwise... i wonder if some of those catastrophic engine failures might have been related to engine over stress and over heating. The 6th cylinder, for, example is known to get the least amount of cooling n the most likely candidate for a crack sleeve. 3rd radiator seems like a cheap preventative measure compared to many other options. Of course, this still does address the need for stronger bolts within the engine which we're assuming the GT3's have.... so if you're going to track a car especially in hot weather a GT3 would certainly increase the odds in your favor, however, for us DD guys the standard Carrera with the larger IMS bearing seems to be doing fine. I discussed this topic with my mech friend at the local p-dealer... he would buy one if he had the cash. I'm going to drive my car now and not worry about this supposed issue anymore.

PHX 911

I had a 2006 Z06 in between my 997.1 & my current 997.2. Although I didn't have any trouble with it in my 7500 miles of use, they have an issue with valve guide wear that manifests itself by lunching a sodium filled exhaust valve. Hard to ascertain prevalence of the failure mode, but like most high performance machines, failure certainly is more likely, and abuse (missed shifts), is punitive.
I think someone mentioned the 2009 and up Z06's were better, but GM recently admitted a machining error on the heads of these cars and is warrantying head rework.
Through internet discussions regardless of brand, it's impossible to establish failure mode percentages, and the manufacturers aren't forthcoming with the data.

Luxter

+1 here.
The third rad, good oil & 160*F T-stat installed too, so I am not going to worry about D-chunks or scored cyliner bores either.
Quit worrying, go driving!
=L=

Para82

Well i've been wondering about this too. I've got a 05997S Launch Edition with 30k miles. I've been considering doing the LM bearing. Not sure if it would be better to just leave it alone, the car drives great.

What percentage of 05 vehicles have had engine failures due to the IMS? Another question, people are mentioning replacing the clutch, what does that have to with a failure?

eflight

What percentage of all 997 cars built by Porsche had an IMS failure, either early bearing design or later one?

What percentage of all 997 with the LNE replacement bearing have had a failure?

Are there sufficient numbers of LNE bearing replacements with similar mileage to the failed original Porsche bearings to be able to statistically analyze the reliability?

From what I can gather nobody knows the actual answer to ANY of those questions, so how can anyone know if they should replace the original bearing with one that is "supposedly" better?

USMC_DS1

The only relationship is that while you have one or the other being serviced... go ahead and do both(IMS and clutch) as labor is the most significant portion(cost wise) of the job.

alexb76

Where did you see a 2006-2008 IMS fail? Please elaborate. Porsche, LN Engineering and the article you refere to have all mentioend that the upgrade has solved the IMS problem, end of the story.

Now, definitely GT3 engine is much more robust for tracking than Carrera engines and that's nothing new or surprising.

pissedpuppy

Seriously, when did all the 996 fear spreading doomsdayers get 997s (LMAO)

It just isn't all the prevalent. As for my 997 (and my old 996) both have REAL Porsche engines....not Mezgers (not yet) but still, REAL Porsche engines!!!

utkinpol

there were failures, even reported here.

all new bearing design did - it _probably_ extended an average time to failure on this bearing 2x times or so. it did not eliminate the cause of the failure - when vibrations and wear deteriorate that seal on the bearing and outside oil gets inside - it washes away original lubricant and then at high rpms this bearing pushes away light engine oil and runs dry efficiently scrubbing off its own metal.
when it starts happening it is only a matter of time for it to fall apart. but, as with all this stuff it depends on many various factors, vibrations, oil, condition of the seal, etc. i also think it depends alot of how accurate an original installer was and how this bearinng was installed or if it was damaged originally during installation.

i think most recently reported failures were related to cracks on 6th cylinder sleeve and rod bolts. that is more typical for m97 engines. but realistically as more m96/m97 motors age we should see an increased number of ims related failures - strictly from engineerinng standpoint it has good chances to happen when more and more motors will start getting to 70-80k miles on them.

Palmbeacher

The larger IMS bearing is ironically at an engineering disadvantage as RPMs increase. Each ball travels farther with every rotation, and any out-of-true is magnified. DD driving, the larger bearing accomplishes what Porsche intended; tracked frequently, it has a somewhat higher theoretical propensity for failure.

Exactly my thought and why I had the LN bearing installed. It can't hurt, it is made of superior materials for an under-lubricated situation, and the part itself is relatively cheap once you're in there doing the clutch anyway. The most important thing is choosing a mechanic who has done the job successfully many times before, as a ham-fisted fitment is sure to be worse than keeping a still-perfect OEM bearing.

Additionally, it would be prudent to check the oil filter for debris prior to fitting a new bearing. If there is evidence the old bearing has begun to shed shards of debris, you would not want to simply fit an LN bearing and go on your merry way. Remnant debris can enter the LN bearing and reduce it to rubbish in no time.

Luxter

Here is some info on the bearings:

Single row replaceable bearing 6204 (Early 2005)
ID = 20mm
OD = 47mm
Dynamic Load = 12,800 N
Static Load = 6,600 N
Limiting Speed = 11,000 RPMs with grease

Single Row Non-Replaceable bearing 6305 (Late 2005 - on)
ID = 25mm
OD = 62mm
Dynamic Load = 23,600 N
Static Load = 12,100 N
Limiting Speed = 12,000 RPMs with grease

The load rating of 6305 (the non-replaceable one) has been increased by nearly 85% compared to 6204.
The 6305 is larger therefore more of the bearing is submerged in engine lubricant all other things equal.
Seems like a substantial change in design.

Cheers,
=L=

USMC_DS1

I think we're violently agreeing here... but in answer to this query - I recall that utkinpol, for example, reported an IMS failure on his '06 C2 and has been one of the most vocal re this topic as a result. Now he has a modified track weapon, does 20+ track days/yr, and his engine blew during one of those track session in the heat of summer last year in Atlanta(hope I captured that accurately). But again... I wonder if this was IMS, heat related(cylinder sleeve), or a broken rod. BTW, I don't have the time to "prove" anything or to link to utkinpol's prior postings and really only he can enlighten us... my basic position remains the same though. I think the potential IMS issue(especially with '06-08) has become a lightning rod issue(blown out of proportion) and is being blamed for what's really happening. Guilt thru associated(996 and 997 engines are similar, same IMS for early 997's, etc) or a case of troubleshooting inference (IMS issues have been known to cause catastrophic engine failures therefore any engine failure must be IMS related). Much easier to just blame IMS if the engine blows... but I believe that there is something else going on here when these engines do fail and I wish there were some real and technical post-mortem reports of these failed engines to clear the air. Again, I plan on enjoying my car and driving the **** out of it. BTW, did you know that we're mortal. I don't really think about it much but someday our own engine will give out one way or another - that's a fact you can bank on. Seems like a motivating factor to go drive that p-car ladies and gentlemen and put all this morbid internet stuff miles and smiles behind us!