21 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHReplacement engine reliability
Reported or suspected cause
failed/failing imsb
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
The master mechanic who did the work is no longer with the dealer to confirm the exact problem, but the service manager believes the issue was a failed/failing IMSB.
Leading evidence: 'failed/failing imsb' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'failed/failing imsb' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check ims bearing-it is the "improved" large bearing' (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.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
The work order also notes the engine was thoroughly cleaned - I suppose due to metallic debris in the engine.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
According to dealer service records, original engine was replaced due to IMS bearing failure in 2007 at about 23,000 miles.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Performed · outcome unconfirmed
The state of the IMSB was not noted in the paperwork, but the IMSB was replaced along with main engine and rod bearings, chains, and oil pumps.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that performed work without a confirmed outcome
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Performed · outcome unconfirmed
Not a lot I know, but it also wasn't weeping or leaking or looking anything but healthy when I replaced my clutch last year.
These are separate views of the same evidence. Frequency alone does not establish a fix, and these counts must not be added together.
failed/failing imsb
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
Read evidence and context
Discussions that report identifying a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Reported cause
The master mechanic who did the work is no longer with the dealer to confirm the exact problem, but the service manager believes the issue was a failed/failing IMSB.
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.
21 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
0 acknowledgements have no verified action link; they do not establish a repair result.
Generation: 20261027T013556Z · outcome-qualification-6. Deterministic extraction; no AI model inference. How we use sources
This November I purchased my first Porsche, a 2004 C2 6 speed with 30K miles. The car�s history is as follows: first owner drove it 3 years (12K mi) when the IMS bearing failed and the engine was replaced under warranty. Soon after she was injured and the car was stored covered in a garage until 2010 (2yr 8mo) then sold to the PO I purchased it from. He is a rennlist and PCA member with (2) 944�s that he raced. His PPI and subsequent 3 yrs of driving 18K mi required only one minor repair, tires, and oil changes. My PPI and Post PI (paranoid I know) were also clean. I am very happy with the car and believe that I got a good car for a good price (I don�t want to hear otherwise).
So my questions are:
Since the engine was replaced in 2007 by Porsche OEM parts were used for the IMS bearing but did they use the �improved� version or the original? How would I determine this?
Could they have replaced the 996 with a 997 (highly unlikely)?
Is there any reason to expect that the replacement engine is superior or inferior to the original?
Appreciate any constructive comments.
Steve
By 2007 any factory replacement engine would have any and all improvements up to that point in time including the larger "improved" bearing found in the 997 in 2007.
This may not be so great after all. Like others have said, you now have a six year old engine that will need the case split to replace the IMSB which is now a PM item. (at least you can remove the bearings outer seal). Let the panic begin.
Take a look at the series number on the oil pan, if it's after M9603AT66565897 you most likely have the bigger bearing/ 997 assembly.
I've got 60K on a motor that's identical to yours, 114K on the chassis
If you find that you have the improved bearing, your comfort is knowing that the improved bearing appears to be much more reliable than any of the previous bearings.
While the new bearing requires much more expense to replace, the likelihood of failure is much lower, and the other forum members are weighing in on that trade-off.
I have a similar situation to yours where my engine was rebuilt in 2011 (by the prior owner) with the newer bearing, and personally I take comfort in the improved bearing.
OP, if you find that you have the non serviceable 997 style bearing and you're still uneasy about it, you can always go the DOF route which is also made for 997 engines.
http://tunersmotorsports.com/?page_id=103
I see no need for panic. Have no intention of doing a PM IMSB. Will drive it, maintain it, and enjoy it.
Excellent point I will file away
As I see it I have a 3 yr engine with 18 K on which I will put another 18K over the next 3 years. Still a low mileage engine.
My situation is almost identical. I'm the second owner of a 2003 996 with about 30,000 miles. I bought the car back in October. According to dealer service records, original engine was replaced due to IMS bearing failure in 2007 at about 23,000 miles. The clutch was also replaced at the time. Replacement engine serial number indicated a rebuilt 2005 engine. I just had a Porsche specialist here in New Jersey drop the trans to check the IMS bearing-it is the "improved" large bearing. They just closed it back up and told me not to worry. I may try a DIY install of the DOF system next spring, but I feel a lot more confident now. I won't complain-turns out I have a low mileage Porsche 911 with an almost new engine and clutch!
Again the earliest confirmed rebuilt number that got the new 997 IM assembly is M9603AT66565897. Next time I've got the car up, I'll shove a boroscope into mine (serial number couple hundred after the number above) to confirm.
I challenge anyone to find more than one documented IMSB failure on a big bearing engine....I don't want stories lads - I want evidence.
I tried this once already - I got one response, but that's it. The big Porsche bearings are simply not prone to failure.
I have a big bearing motor in my car with 80,000 miles. Not a lot I know, but it also wasn't weeping or leaking or looking anything but healthy when I replaced my clutch last year.
edit
That DOF looks pretty cool actually, I hadn't heard of it before this. Maybe at the next clutch change, although even these guys say:
"We have even seen IMS bearing failures on early 997/987 models...."
and we all know by now that the early 997 engines used the smaller IMSB.
About this, every 1mm increase of the radius adds 6.24mm of the race; I'm guessing porsche shove the bigger one in there to deal with the heat disputation.
Halik, what info do you have about replacement engines after...5897 having the larger bearing? Mine was replaced in 2005 and the number ends in ...5912.
Thanks
Thanks, I knew mine was made about the time of the changeover but had not seen a serial number associated with the switch. I have about 35K on the engine and it may be awhile before it comes out for a clutch. Then I will know for sure.
Continuing this thread, reiterating the question Jasper posted awhile back, but more specifically for engines replaced with the larger bearing .
I too am curious about the durability of the big bearing. They have been used in 3.4 and 3.6 engines for 7 years now which seems plenty long enough to begin to notice failures if they are going to happen in significant numbers.
My experience is a 3.4 engine in a 996.1 that was rebuilt in 2011. The engine had suffered some internal failure (at 33K) that took out the oil scavenge pumps, and broke the timing chain(s). The state of the IMSB was not noted in the paperwork, but the IMSB was replaced along with main engine and rod bearings, chains, and oil pumps.
The work was paid for by the owner's aftermarket warranty and I would suppose that the IMSB would not have been replaced unless it had failed or was failing.
The work order also notes the engine was thoroughly cleaned - I suppose due to metallic debris in the engine.
The master mechanic who did the work is no longer with the dealer to confirm the exact problem, but the service manager believes the issue was a failed/failing IMSB.
The car now has 58K miles and I just changed the oil for the 3rd time that I've owned it. I've found no debris in the filter or filter canister ever, and the engine uses no oil whatsoever.
So, does anyone have first hand knowledge of an engine that has received a large bearing which has subsequently failed?
This is a source reference. Confirm exact model applicability in the original material.
