From the 997 work shop manual I extracted the following information on which engine has the smaller or revised larger IMS bearing:

Base engine (3.6) has designation "M96", can have the smaller IMS or revised larger bearing, you will need to know your engine number in order to determine which one you have:

Engine (3.6) number up to M96/05 69507475 has the smaller IMS bearing and Engine number from M96/05 69507476 has the larger revised IMS.

"S" Engine (3.8) has designation "M97", can have the smaller IMS or revised larger IMS bearing:

Engine (3.8) number up to M97/01 68509790 has the older IMS bearing and Engine number from M97/01 68509791 has the larger revised IMS.

The smaller IMS bearing can be replaced, this requires removing the transmission in order to get access to the bearing. The flange uses a 13mm center nut.

The larger IMS bearing can also be replaced but a tear down of the engine is required. The flange uses a 22mm center nut.

Jophiel, I'm very curious to know which IMS bearing was in your engine. I have done a lot of searches and have not found a failure with the larger revised IMS bearing. Often when I read about a IMS failure it never states if the engine had the smaller or larger IMS bearing.
Jophiel, I would appreciate if you can let us know your engine number so I can document in more details the IMS bearing failure.

 

I talked to the dealer and found out the failed engine's information. According to your information, I had a the older, smaller bearing. At this time I don't want to publically release the exact serial on the engine until my warranty work is completed.

Thanks for your info!

 

Thanks for the reply,

I would definitely request a "new" engine with the larger revised IMS bearing!

Good luck.

 

Dumb question: (If any) What's the failure history on the larger bearing? Do we know if the larger bearing properly addressed the IMS failure?

Obviously they upgraded it for a reason, I am just wondering if that was a definitive fix.

Thanks.

 

yes, the owner is a member here and in rennlist. we has put like 10,000 miles on top of that...

 

All Porsche remanufactured engines have used the 3rd gen. IMSB design since 2006.

 

The last design IMSB has failed, but like the others there are no statistics available to show how many. The original dual row bearing is the strongest IMSB 1996-2001

 

I think having those bearings where they are, for the size / power of the engine is just a critical design shortcoming in the water cooled engine(s).

 

good question, so far I am not aware of any failures with the larger IMS bearing, hopefully there won't be a history and we can put this issue to rest. I believe Porsche was aware of the issue and went with the larger bearing.

Here are some data between the smaller and larger bearing:

Smaller single row bearing "6204"
ID = 20mm
OD = 47mm
Dynamic Load = 12,800 N
Static Load = 6,600 N
Limiting Speed = 11,000 RPMs with grease

Larger single row bearing "6305"
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 the larger bearing has been increased by nearly 85% compared to the smaller one.
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.

 

I agree, this is why the 997.2 engine eliminated the IMS...

 

The larger revised "6305" single row bearing has a load rating similar to the dual row bearing "6204".

 

Good information guys. Here's another question. Can the 997.2 engine just "plug and play" into the 997.1? What would have to be upgraded for a 2005 c2s to take on the 997.2 s motor?

My thinking is if the warranty company pays for the replacement of a 997.1 engine, maybe I can spring more for the upgrade.

Just thinking out loud.

 

Unlikely. Then they would be on the hook for future TT or "other engine" repair. He should be ecstatic that he had the forethought to buy the extended service plan. That's exactly why I've done it with my last 3 P's.

 

I'm pretty sure you'd need all new computers and maybe even a gearbox.
That's if you could even get your hands on a crate 997.2.
Cheaper to just trade up to a 997.2 car.

 

OK...so after some time on my back trying to read my engine code, I have learned two things.

First...the engine code is not easy to read. I couldn't make it out with a flashlight as the indentations had no contrast vs. the surface of the plate they were stamped into. After a little trial and error, I was able to get them to show up by scratching a #2 pencil accross the surface then using my fingers to wipe away the pencil from the surface. The pencil marks remain in the indents and gives some contrast.

Second...engine serial is M97/01 685085XX (didn't want to give full digits) so it has the smaller bearing design. That puts me back to square one. 46K miles on a '05 with the smaller bearing, driven fairly regularly, no warranty, waiting for clutch to fail so I can upgrade the IMS part. The silver lining is I only need to drop the tranny to change out the IMS...bad part is pretty obvious. I am running a risk here.

Anyone have a good feel for where these clutches go out? I am doing mostly city, probably not too easy on the clutch. If I remmember, I think my 993 started slipping at like 50ish...but 997 has a bunch more power.