The cause of the problem has been researched by experts in the Porsche business and has been found to be loss of lubrication to the bearing, The reason for this is that the original bearing is a sealed unit, with grease packed inside - similar to a rollerblade wheel bearing. However, over time, the seal wears just enough to allow the grease to escape, yet not enough to allow engine oil in the area to seep in sufficiently enough to lubricate the bearing. It scores eventually, and can eventually just fail. The newly designed bearing by LN Engineering redesigns the bearing to eliminate the seal and allow engine oil to freely lubricate the bearing. Additionally, the bearing is made of a much more robust material that resists scoring, even when dry.

It's something Porsche should have come up with originally.

Thanks for that explanation....so it looks like this should be done, eventually

I looked at this closely when searching for a 996/997. My solution was to buy an '05 997, which is the last year that has a replaceable IMS bearing, with a 2 year CPO warranty. At 1 year and 11 months into the warranty I plan to replace the clutch and IMS bearing.

Another weak point, at least on the '05 model, seems to be ignition coils. I got a check engine light a few weeks ago. I took it to the dealer and they replaced all 6 coils.

The LN IMS bearing is a ceramic bearing made in Japan according to Charles Navarro of LN and, as has been mentioned, is an open bearing that allows motor oil to lubricate it. Ceramic bearings were tested by LN and shown to outlast metal bearings 5:1. LN does recommend a 5-40 wt. oil instead of the 0-40 wt. recommended by Porsche and a 5K mile oil change instead of the 15K recommended by Porsche.
LN has recently marketed an IMS Guardian that detects metals in motor oil that could indicate an IMS failure. The technology for it was developed from similar sensors used to detect failure in aircraft motors
Pelican is, or has, marketed a replacement IMS bearing but, correct me if Im wrong, is not a ceramic bearing.
As far as the frequency of IMS failures the only one who really knows is Porsche and they are not divulging that information.
Fortunately, or unfortunately, there is a plethora of information on the internet that may possibly be misleading depending on who publishes it and what they have to gain. Typically you will not be reading testimonials as to how long someone's motor lasted.

Another thing I did before buying my car was talk to Porsche Racing Parts : Engine Performance Parts : Brake Parts : Used Porsche 356 : 911 : 912 : 914 : 944 : Porsche Boxster Parts : EBS Racing Inc.

I just wanted to know if the worst happened what would it cost to have my engine rebuilt if I shipped the engine to them. They said about $7,500 so I just kept that in the back of mind for worst case maintenance cost. Certainly not cheap but at least I knew it going in.

http://forums.pelicanparts.com/porsche-996-997-forum/658149-well-finally-happened.html

Over on the 996/997 forum.......

That looks more like RMS failure.

Interesting, in reading another article is said to use oil with more zddp than Mobil 1 has in it, I bet if you are under warranty and had a failure, Porsche would use the fact you weren't using Mobil 1 to void your warranty :)

Bob

I replaced the IMS bearing on my 2002 Boxster with a dual row LM bearing at 51,000 miles and it failed 55,000 miles.

10 year old thread, just sayin'.

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Such a bearing may "fail" in 4k miles, but it seems suspicious as such a failure would likely be nothing more than a bit of noise. That is, catastrophic bearing failure (rolling elements) requires a lot of cycles.

Also, 4 posts?

hmmm.

http://forums.pelicanparts.com/uploa...1662241889.jpg

A lot of the posters in this thread are gone....

rjp

10 years just like that! Meanwhile... Does someone want to tackle my question?

Why doesn't Porsche fix the problem?
Because Porsche has become more interested in volume sales and profit instead of excellence.

I have a different view.

Despite what "Bell" says, and I consider him a friend and very experienced and incredibly knowledgeable expert tech, our shop experience has been different. But, that makes the point that it is great to gather as much info as possible from varying locations and experts. I 100% believe what he says.

Up here, where summers are hot and winters are very mild,(rarely below freezing) we see far more bore scoring issues than IMS issues. We build on average 6 M96/97 motors a year, 5 of those would be from Bore Scoring.

That said, we do countless IMSB replacements as preventive maintenance (common in our marketplace) that perhaps we do not get to see as many failures.

The failure is real. But these motors have other issues that are not really preventable (parts wise) and we see far more taken out from these issues.

All of that said, It is a good investment to solve the the IMS issue before it becomes an expensive problem.

Cheers

It was probably more cost effective to keep replacing motors under warranty since they knew they had a new motor design coming in 2009 (I think that’s when the design change was).

The bearing got massively improved in late 2005. It is HIGHLY unlikely a big bearing motor will suffer a failure of this sort. That said, again, there are other issues these motors have. Not Porsches best work.

Cheers

There's a bit of a backlog. They're still working on that head stud issue...