IMS data collection update - 132 cars (Page 3)

rottenbend said:

Chris_in_the_UK said:

Will be interesting to see how many have changed the bearing due to paranoia rather than need?

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Difficult to prove that one, though. You could look at it the other way and it might be interesting to see if any bearings that have been changed consequently failed? If not (or the failure rate is significantly lower), it's difficult to say that changing is necessarily a bad thing, if the result is a lower failure rate and less paranoia? However, I suspect the current sample size is not big enough to be conclusive one way or the other.

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In the quiet words of the Virgin Mary... come again?

rottenbend said:

Chris_in_the_UK said:

Will be interesting to see how many have changed the bearing due to paranoia rather than need?

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Difficult to prove that one, though. You could look at it the other way and it might be interesting to see if any bearings that have been changed consequently failed? If not (or the failure rate is significantly lower), it's difficult to say that changing is necessarily a bad thing, if the result is a lower failure rate and less paranoia? However, I suspect the current sample size is not big enough to be conclusive one way or the other.

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Maybe I have not been clear?

I meant how many people had a perfectly running car with no issues but they have changed the bearing anyway as a precaution. I am not saying that changing it under these circumstances is bad, just curious how many were changed as a precaution.

alex yates said:

rottenbend said:

Chris_in_the_UK said:

Will be interesting to see how many have changed the bearing due to paranoia rather than need?

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Difficult to prove that one, though. You could look at it the other way and it might be interesting to see if any bearings that have been changed consequently failed? If not (or the failure rate is significantly lower), it's difficult to say that changing is necessarily a bad thing, if the result is a lower failure rate and less paranoia? However, I suspect the current sample size is not big enough to be conclusive one way or the other.

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In the quiet words of the Virgin Mary... come again?

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Sorry it was a bit late when I wrote that and I misinterpreted Chris's post.

I think the choice of whether or not to change/modify the bearing seems to depend very much on the type of bearing. This has been talked about for a while and this dataset seems to support those theories. If I bought a 3.4 I probably wouldn't bother, other cars I might do it as preventative measure:?:

What is for certain is that the more owners know about this issue and how it may or may not affect their car, the better more informed decisions they can make. Which can only be a good thing :thumb:

Chris_in_the_UK said:

Maybe I have not been clear?

I meant how many people had a perfectly running car with no issues but they have changed the bearing anyway as a precaution. I am not saying that changing it under these circumstances is bad, just curious how many were changed as a precaution.

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:thumb:

Chris_in_the_UK said:

alex yates said:

I'll post some info over the weekend on replacements.

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:thumbs:

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9962 C2 X51 3.6 replaced at 49,000 (preventative)
9962 C4S 3.6 Bearing replaced for peace of mind and showed minimal play. Dust shields removed
9962 C2 3.6 Parr replacement - preventative - original found to be in perfect condition. Bearing replaced for peace of mind and improve residual value of car
9962 C2 3.6 IMS replaced October 2014. Replaced IMS with modified kit from Northway alongside with new RMS which needed doing. Mix of Porsche and Specilalist history
9962 C4S 3.6 replaced twice in the space of a few months by the previous owner at Parr (original replacement LNS? failed very quickly and engine was leaking oil?). assuming it actually failed, the original was replaced Q4 2012
9961 C4 3.4 replaced by me at 95k as a preventative measure. Bought from Pelican parts. Single row bearing used to replace double row. Old bearing was in perfect condition.
9962 Anniversary 3.6 Upgraded Hartech bearing now fitted
9962 C4S 3.6 I had the bearing replaced when I bought the car as a preventative maintenance thing (LN bearing). (The original turned out to be fine BTW).
9962 C4S 3.6 IMS was replaced in February 2011 during Hartech engine rebuild. The rebuild was primarily to fix bore scoring, I assume IMS was replaced as a preventative measure rather than failure.
9962 C4S X51 3.6 Previous owner elected to go for a replacement clutch/RMS seal/IMS bearing (ceramic I think) during a major service in 2001 @ 12,000 miles. Not due to any problems but rather as a preventative/upgrade.
9962 C2 3.6 bearing: Original removed but was till in good order, @58k , bearing 2: Hartech, no seals: Removed but still in good order, @85k, bearing 3: Hartech, no seals: Currently fitted.

Data collected so far for 72 cars (28th April 2015).

Here's a couple of bar charts showing which engines and models have sustained a failure:

Total number of failures - 8.3% (Not including the LN as a original failure)
of which 3.4 - 0% and 3.6 - 11.3%
of which all X51 - 0%, C2 - 11.8% and C4S - 13.3%



Last reported failure was July 2014 (not including the LN failure).
I'm starting to wonder if the reported failures are anything to do with Porsche moving to a 2 year/20,000 mile service plan around the same time they were registered :dont know:

Clean oil and proper levels contribute to mitigate IMS failures, so that is not a bad hypothesis.

Agree two year intervals are likely to be a contributing factor, but find it unlikely that all those cars which had IMS failure wouldn't have if they'd had more regular oil changes.. I reckon a fair few 04 owners still go for annual servicing anyway.

For what an oil change costs it's a no brainer (price of filling a tank of fuel). Why risk the cost of an engine failure :dont know:

jm24 said:

Agree two year intervals are likely to be a contributing factor, but find it unlikely that all those cars which had IMS failure wouldn't have if they'd had more regular oil changes.. I reckon a fair few 04 owners still go for annual servicing anyway.

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You are contradicting yourself?

Chris_in_the_UK said:

jm24 said:

Agree two year intervals are likely to be a contributing factor, but find it unlikely that all those cars which had IMS failure wouldn't have if they'd had more regular oil changes.. I reckon a fair few 04 owners still go for annual servicing anyway.

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You are contradicting yourself?

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I simply meant that of those 2004 cars that did switch to bi-annual servicing and had IMS failure, the less frequent oil changes were still only a contributory factor. I.e its an inherent design fault (albeit over hyped) for which oil change frequency can influence the risk of failure.

It would be interesting to know the service intervals of those 2004 models that have failed to see what proportion had annual/bi-annual servicing :?: If they all had the bi-annual servicing it would certainly give more credence to the hypothesis

It is interesting to see how many bearings were replaced and noted to be perfectly sound. I've been reading an interesting thread on Rennlist where the Merkins seem to fanatically replace the IMS as the stateside 996 engine guru states it is essential to do so. They are investigating a failure of the ceramic bearing solution which has lunched an engine. Our own 996 engine guru (Baz Hart) doesn't advocate changing is essential, even though he has a solution himself. It'd be interesting if the ceramic solution turns out to be as risky as the original Porsche design.
It is also interesting to note that the majority of failures are with cars serviced every 2 years.
Great work Alex, the bore score one will be even more interesting, but, can we pick up whether manual or tip? :thumb:

But we don't know that the majority of cars were serviced every two years do we? We know the majority had 2 year service schedules, but theoretically could have all had annual services in this sample..

jm24 said:

But we don't know that the majority of cars were serviced every two years do we? We know the majority had 2 year service schedules, but theoretically could have all had annual services in this sample..

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Which, again given your earlier contradiction may be largely irrelevant.

Chris_in_the_UK said:

jm24 said:

But we don't know that the majority of cars were serviced every two years do we? We know the majority had 2 year service schedules, but theoretically could have all had annual services in this sample..

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Which, again given your earlier contradiction may be largely irrelevant.

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I don't see any contradiction and went on to explain what I was getting at. Feel free to explain what you specifically see as contradictory, but I'd just like to have as much understanding of the contribution of oil change frequency to IMS failure as possible.

Unless we know how many of the failed 04 cars were serviced bi-annually, we are making assumptions about the extent to which oil change can/does influence IMS failure. Perhaps they were all bi-annually serviced in which case it would look like a very significant factor. If though say half still had annual servicing, then its a somewhat different story. I'd just like to have as informed idea as possible.