25 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHIMS - not the usual question
Leading reported evidence
Install later/revised/larger bearing
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
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Read evidence and context
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Performed · outcome unconfirmed
Someone split open the case and installed the later/revised/larger bearing with a new IMS shaft.
Leading evidence: 'Install later/revised/larger bearing' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is '2005' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check engine numbers it's the original 2003' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed
It will be oil lubricated from now on, and there's a very, very high probability that it will be fine (this is the conclusion of multiple experienced indie mechanics with several years of history doing this on M96/M97 engines).
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Suggestion · Original poster
He assumed it had had an engine replacement at first, but checking the engine numbers it's the original 2003.
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Suggestion
The dealer would just replaced the entire engine and be done with it.
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Performed · outcome unconfirmed
It will be oil lubricated from now on, and there's a very, very high probability that it will be fine (this is the conclusion of multiple experienced indie mechanics with several years of history doing this on M96/M97 engines).
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
25 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Generation: 20261027T082735Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
Hi,
I have a 2003 C2 996 in for RMS and IMS.
Just heard that the IMS can't be removed as it is the 'new' M97 type larger bearing that requires the engine strip. The engine is original and the engine number is way before that cross over point fo the newer M96 engine after 2005
First question for those that know - Can the later M96/M97 larger bearing be retrofitted (assume the whole shaft) with the old crank case?
The only thing I can see in the reams of paperwork is a an invoice from Porsche in 2007 for a customer contribution to an RMS swap. Was Porsche updating IMS to the 2007 style as a matter of course to older M96 engines during this period?
THanks
Dodge
Not an original engine...If it's the m97 style (not a bad thing) bearing, just have them pull the grease seal and button her back up. That's about all you can do.
Look at the serial #
Yes. Porsche indie. he's done the RMS and has the IMS replacement ready to go in, but just rang to tell me he can't do it due to it being the newer bearing type.
No. 100%. He can't physically remove the old bearing as it is the type it needs the engine splitting to get out. He assumed it had had an engine replacement at first, but checking the engine numbers it's the original 2003.
This is the basis for my question really. The M97 style bearing was going into M96 engines from 2005. In 2007 my car went into Porsche for what looks like an RMS swap (only done 9000 miles at that point, so an early swap out for that)
Given the current IMS at the time was the post 2005 one (what I've been calling the M97 one), the court case with the old M96 single row version. If there was a question mark over the IMS at the time that Porsche went to repair the RMS, would they have swapped out the whole IM Shaft. The LN engineering solution wasn't really around then and I suppose Porsche wouldn't use anyway. So, I can see how it might have happened at that point in 2007, just not sure if it is mechanically possible just to swap the shaft and bearing with it, or whether more extensive engine work would be needed, different journals?
Was this standard practice for Porsche at that point in time?
They would have replaced the motor and it will have "AT" in the serial # like the picture I posted.
Can you get a picture of your serial # and flange nut from your mechanic to confirm?
Something isn't adding up here. I don;t thin Porsche was splitting cases at the dealership. That's a lot of hours and knowledge to complete a job like this. The dealer would just replaced the entire engine and be done with it.
Interesting. I'd be interested to know if they porsche could do it.
When I shopped for imsb replacement, Local Porsche dealership said no to LN Retrofit. They only install Porsche parts, so that meant open up and replace the whole shaft etc. With porsche parts.
The answer to your first question: Can the later/larger bearing be retrofitted? Yes, that solution works perfectly fine on LATER 996's with the single row chain, and that seems to be what was done on your car. I don't see any other way you would have the original case and the larger bearing. Someone split open the case and installed the later/revised/larger bearing with a new IMS shaft. In 2007, that was certainly a reasonable solution.
The solution for your current situation: As 808Bill said, remove the rear grease seal and close it back up. It will be oil lubricated from now on, and there's a very, very high probability that it will be fine (this is the conclusion of multiple experienced indie mechanics with several years of history doing this on M96/M97 engines).
If you need total peace of mind and want a virtually bulletproof solution, you need to convert it to an oil-fed journal bearing, like all previous 911 engines had in that location (and the 996 Mezger engines still had). In your unique case, that's a very expensive job because the case has to be opened up. I really don't think it's necessary in your case.
FYI for anyone with an early 996: The earliest M96's had double-row chains (between the crankshaft and IMS shaft), and at some point they converted to single-row chains. I really don't know when that happened, but I'm guessing late 99 or somewhere in the 2000 model year. If you have a later single-row chain, it's a direct swap to the newer IMS shaft and larger bearing. If you have an early double-row chain, it's not that simple because you can only get a newer IMS shaft with the later single-row sprocket. Bottom line, if someone has an early 996 with a dual-row chain, they would have to change the IMS shaft/bearing combo, the crankshaft, and the (front) timing chain. It's technically a viable solution, but not the best direction to go for someone that currently has the small bearing - it would be better to just go straight for the journal bearing retrofit.
If my memory serves me correct, Porsche didn't start introducing the large ceramic M97 bearing at the factory until 2006, if a 996 was serviced under warranty post 2006, then an engine replacement would have the "AT" (German - Austausch) in the new serial number and include the newer M97 bearing. That serial number you have listed is a M96.03 and so the bearing will be the most failure prone - single row.
The best way to confirm is ask the mechanic to take a picture of the bearing with the flange removed. Post it here on Rennlist and the experts will help you confirm on way or the other. As it stands, my vote is the mechanic is mistaken about the bearing OR someone have rebuilt this engine.
Make sure to get a pic of the IMSB flange...This is strange if true!
Have you tried contacting the previous owner or the shop/dealership that did the work?
I'm pretty confident in the mechanic. a proper Indie with lots of rebuilds, IMS, etc under his belt. He also has a 997.1 in for IMS at the min and that has the M96 engine in and he has swapped that one out today as it has the older style single row in. I will be trying the Porsche dealer later today to see what they say, although it was 12 years ago.
That 997.1 was probably a 2005. They all had the single row bearing. I'm assuming the car is still at the indy waiting you decision? Why not ask the mechanic to take a picture of the bearing's flange and the serial. It's not like people don't have access to cameras. Be kind to him and try to explain your position. That is, you're attempting to get some history on the car from Porsche and photos would help the process.
This is a source reference. Confirm exact model applicability in the original material.
