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IMS bearing failure for your 996, Y or N? tell us (yr, 996 Mk1 or MK2 failure mode)
As requested I have posted this poll.
Many have been asking to understand how many of the 996 cars have had IMSB (intermediate shaft bearing) failures. Although the people on this board are not necessarily a random sampling of 996 owners many have asked to see a poll to get a better sense of it.
Please vote only once for each 996 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 and when.
Please let us know if there were any mitigating factors (low oil, overheat, etc) that might have led to the failure
Please post only about IMS failures, this is not about RMS 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)
Please ONLY POST DATA HERE. Not discussion.
Hopefully this will help owners and soon-to-be owners get a sense of how frequently this occurs.
I bought a ‘99 C4 almost exactly a year ago with 109k miles. I had always planned on doing the IMS bearing with the next clutch replacement. But clutch has plenty of life so I assumed this was a ways out.
Left town for a few months and returned home to two big puddles under the car. One right beneath the bellhousing. See photo — the smaller of the two large leaks was the one under the RMS, the larger was actually a cracked coolant expansion tank.
Decided it was a big enough leak to investigate even though primary suspect was RMS.
Dropped the tranny, and decided to replace the IMS bearing proactively with the LN retrofit kit.
Good thing too… IMS bearing was completely shot. My car is a very early MY99, with a dual row bearing. It was MISSING ball bearings, and there was a ton of play in the bearing itself. Honestly a miracle that the failed bearing hadn’t led to anything catastrophic. It was truly a ticking time bomb.
I’ve done Blackstone oil analysis with each oil change since my ownership and never saw any sign that the bearing was failed, save the leak in the garage.
Bullet dodged!
Weepy RMS leaked onto the IMS bearing, at this point not clear where the source of the leak was. Failed dual row IMS bearing. Engine survived. New LN engineering bearing.
No issues on my 996 mk2 40th anniversary.
As many veterans of this forum know, these polls suffer from selection bias, incomplete sample size, unknown denominator, fake posts, etc.
But some data is better than no data.
70,000 mile on a dual row bearing and no problems. At 50,000 mile when I had the engine dropped to fix a cracked head/intermix I did replace the IMS flange with the updated flange and removed the seal on the bearing. Next time the engine is out or the trans is dropped I do plan on installing the LNE bearing.
Had the the IMS flange replaced (+RMS) 1.000 miles/3 months ago at local OPC. At the time I didn't have enough knowledge to ask the OPC how the IMSB was or if they have replaced the IMS flange because they "were in there"... Just knew I had a leak and asked them to solve it...
They just suggested replacing the clutch at the same time, which I did.
I estimate doing 5.000 miles at max this year, so maybe next service I will ask the OPC to replace it for the LNE or the INSARO IMSB. On the other hand, I have read at 911uk forums that Hartech (major UK M96 rebuild specialist) doesn't like to replace IMSB on currently "good" running 996's...
This IMSB thing is a bit confusing to a newbie 996 owner like me...
02-03-2013, 10:41 PM
IMS bearing failure for your 996, Y or N? tell us (yr, 996 Mk1 or MK2 failure mode)
