Sapientoni

Any ball bearing has a "designed service life" which is affected by contamination of the bearing, overloading of the bearing, or exceeding the rpm design of the bearing. I have replaced a 2006 3.4 IMSB that failed at 145,000 miles. It did not bend valves nor suffer any collateral damage (save financial and loss of use) because it had just come off a lift in prep for the track (brakes being serviced) and made one helluva racket! It had apparently been dying for some time and that was just the LUCKY timing of the total fail. The inner stub flange for the 2006 (at least) has only a 1 mm clearance of the inside of the IMS. This stub supported the IMS for the 6 miles limp home. Shoulda flat topped it, I know. On a bb somewhere is a pic of the inner race which had spalling on 180 degrees of it. This was the pressure side. Ball bearings are like basketballs rolling in a bowling gutter under pressure. The pressured areas are flexing a minute amount and at some point, they can't rebound to the original shape. When the little pieces start flaking off, the failure is accelerated by rolling thru the trash. Now they die.

Sapientoni

RE:the RMS. It's a rubber piece. I put a clutch in a 928S4 and the rear seal was dry as a chip. Two weeks later I was having it aligned for d.e. and it was leaking like a sieve! Lesson, change it anytime you're in there. Of course me being the clutch mechanic and they are so easy on the 928, it was just a minor incovenience, but if I'd been paying someone, it would have been big bucks for a $40 part change.

jdjones2010

Guys, it seems like i'd seen on here somewhere before that IF you're going to have one of these issues, that they Usually happen Before the 60k mile mark compared to After! Is there any truth to this, Thanks & Happy Motoring!

mikefocke

You can think of failure causes as falling into several areas: manufacturing tolerances, simple part failure, caused by failure of another part, wear, poor oil change habits and installation variables. The well used higher mileage car has several of those causes ruled out. So are the odds of failure by increased wear due to the number of revolutions more than the causes ruled out? Who knows.

rick1

I proactively had IMS bearing replaced at 60k miles. My IMS bearing settlement claim for my 2001 996 was rejected because it was manufactured before 05.04.2001. The following is a quote from the email from the plaintiff attorney's email explaining why my claim was rejected:

"Based on the information provided to us by Porsche in discovery, the failure rate of vehicles with your version of the IMS, from 2001 to 2005, was in the range of 4 to 10%. Porsche began using that particular version of the IMS that was subject to the higher failure rate as part of its production runs exclusively as of May 4, 2001. This same IMS model was used through February 21, 2005. The failure rate of the IMS in Porsche vehicles pre-dating May 2001 and post-dating February 2005 was documented at less than 1%. The higher failure rate between May 4, 2001 and February 21, 2005 is the reason why some vehicles are included and others are not. "

Mechintosh

I dropped my 02 996 C2 off at Flat6 over the weekend to Proactively have the IMS Procedure done. My 996 has 76K with a regular service history. Also replacing the Water Pump and Air to Oil Separator. I want to enjoy the car and not have to worry about when the bearing will let go.

Picking her up on Friday.

JP66

Hello to All,

About 2 weeks ago I purchased a 1999 996 C4 with 58k miles on it, but always dealer maintained. I immediately sent it to my local tech for an LN IMS upgrade, new brakes, and new tires. Yesterday the tech called and said they were having trouble getting the IMS bearing out. It seemed to be stuck. They also said there was no sign of bearing failure. They soaked it with WD-40 and will try again today to remove the bearing. I asked them to now pull the oil pan and open the oil filter.

Question:

1) Has anyone ever experienced an IMS bearing that was exceptionally difficult to take out or worse yet actually frozen to the shaft?

Flat6 Innovations

Your engine utilizes a dual row IMS Bearing with an internal wire lock. This lock must be broken to remove the ins bearing. This does take a lot of effort, but if they are using my extraction tools, or my Fautless Tool, the job is possible.

It sounds like this shop lacks experience with a dual row extraction. That's not good.

JP66

Wow! Thanks for the quick reply, and I am excited to have one of the nation's finest authorities on Porsche engines answer my question. Thanks again.

I did ask if he knew about the 1999 having the internal wire lock, he claimed he knows and has done them before. In your experience have you ever had or heard of an IMS bearing that wouldn't come out with the proper tools?

I totally agree with your sentiment though; he did come highly recommended from a fellow that uses him to maintain his spec boxster, and he supposedly does a lot of Porsche work, but he is most definitely not exclusive to Porsches, and now I'm nervous. I think I'll take a trip to the shop and look at what he's using as an extraction tool. Is that obnoxious?

Flat6 Innovations

Some are tougher than others, but I've always removed every one. In fact, a super tough dual row bearing extraction is what lead to my extraction tool development.

I have broken center studs during extraction efforts, and if that happens the tech will have to use the broken stud accessory in the tool kit.

The trick here is to place a load on the extraction tool and walk away from it. Every 5 minutes or so crank the tool down harder and walk away again. Keep doing this and you might hear the tool, and bearing break free, and shoot across the shop. Been there.

The key is letting the heavy load be placed on the bearing for a period of time, rather than just being Goliath and wrenching it out.

He now HAS to remove the bearing, because the bearing has seen dented races and ***** from trying to be extracted.

dwdunn

2002 C4 cab, 72,000 miles, IMS bearing went, scarred cylinder walls, case okay [ now bored to 4.0 liters], everything else was good. IMS bearing gave way with no warning; nothing in the oil or filter, checked it religiously. Single row.
8% of cars?! To me, it happened 100%! Not giving up on the car, I plan on keeping it. The engine is at Vision Motorsports for the full meal deal rebuild.
dwdunn

perryinva

Had my '02 C2 with 55k miles IMSB done (LNE, single row, with serial number sticker) last week, along with the clutch, pressure plate and bearing, and RMS, at Lufteknic in Richmond. IMSB was perfect, seals intact, and full of grease. Smooth as butter. On top of that, RMS had already been done and was bone dry, but it was a red & blue aftermarket, so I had the latest Porsche one installed, AND the clutch disc had been replaced as well! It had an '05 DOM on it. So, in essence, all the work was unnecessary! But amazingly, the engine shifts, feels and sounds significantly better! Of course you get a fresh oil change with that, which may account for a lot of it, and they use Liqui Moly Hi Tech 5W-40, which I've never used. $3300 out the door, but documented peace of mind, now..

Zeus993

I'm in the care of a year 2000 Carrera with just over 125K miles on it. RMS replaced with new clutch but not IMSB. The engine is running very very free and shows no signs of anything. It's fantastic.

The door manf date of 04/2000 puts the engine design in the pre-May 2001 to Feb 2005 period (where the incidence of failure was 4-10% and PAG covered the IMSB problem) with the % failure of <1%.

Question: Obviously it's best to get the IMSB replaced but has anyone here actually had a year 2000 IMSB breakdown?

Tx in advance...

AA717driver

Just did my first oil change after IMSB replacement. My filter is littered with metal.
















I know someone else had this happen but couldn't find the thread. Should I do another change in a short period? Flatbed it to GA...? I found the previous thread and the metal is ferrous.

Thanks in advance!

TC

ETA: Sending my oil out for analysis first thing tomorrow.

prc197

Ok guys,

I just got my first 911, its an 03 C2 6sp with 90k miles
I read all I could find on the IMS issue and still don't have a conclusive answer, maybe there isn't one.
From what I have read I would have to conclude that at 90k miles, if it was going to fail it would probably already have. We'll never know the real effected population because many good bearings have been replaced as a precaution, and even those replacements aren't a permanent solution. Please advise, thanks