996 M96 IMS failure symptoms..?
Discussion
As we all know the M96/97 IMS bearings are a weak point on these engines, we know they fail, and the results are a destroyed engine as the bits are then picked up in the oil and pumped around. This result has been well documented, and a retrofit bearing pack is the answer.
Porsche sent these engines out with either of 3 sealed bearing types, a single row ball race, then a double row ball race, which worked out too expensive so they went back to an improved single row I believe.
Q, is it the case that this will fail it's just a matter of when..?
Q, do they typically fail at certain mileages..?
Q, are there any audible symptoms that you can pick up on to indicate it's 'work in progress'..? or do they just let go 1 day.
Q, how many hours work is it to change 1 as a preventative measure.
Q, or is it a total lottery, and they can run for 100K+, and a few folk are just unlucky..?
A small leak is common, mines no different, but that could be RMS or IMS or both..!
I've never seen any oil spots on the floor tho'.
Mine is an -04- done 65,000, had a clutch, but not sure if they changed any seals when it was done tho'.
Porsche sent these engines out with either of 3 sealed bearing types, a single row ball race, then a double row ball race, which worked out too expensive so they went back to an improved single row I believe.
Q, is it the case that this will fail it's just a matter of when..?
Q, do they typically fail at certain mileages..?
Q, are there any audible symptoms that you can pick up on to indicate it's 'work in progress'..? or do they just let go 1 day.
Q, how many hours work is it to change 1 as a preventative measure.
Q, or is it a total lottery, and they can run for 100K+, and a few folk are just unlucky..?
A small leak is common, mines no different, but that could be RMS or IMS or both..!
I've never seen any oil spots on the floor tho'.
Mine is an -04- done 65,000, had a clutch, but not sure if they changed any seals when it was done tho'.
Edited by RatBoy M3CSL on Sunday 8th September 11:16
Any bearing failure is not usually instantaneous, that is most unlikely, it would take something like an impact of sorts to cause that.
The "problem" with bearings is that there are only two types of bearing - a perfect one, and a crap one, with nothing in between. As soon as a bearing starts to wear, the deterioration thenceforth is relatively rapid. They are not like regular wear items which are designed to deteriorate (wear) from day one.
Obviously the higher the loading, the more rapid the deterioration and eventual destruction of the bearing once there is an initial amount of wear.
However there is definitely a time window from the start of wear to total destruction. How long this is, is hard to tell, but I really don't think it's very long for an IMS bearing, considering the RPM.
Nevertheless this time window is the basis of how IMS guardian is supposed to work, by (literally) picking up fine pieces of metal in the engine oil and reporting their presence to the driver.
Another option I see, that may be more complicated and costly to develop, is to have some form of acoustic sensor and related circuitry that could listen to the no doubt specific noise made by a bearing on the way out.
That's how most pinking sensors work, so it's not Nasa - grade engineering.
The "problem" with bearings is that there are only two types of bearing - a perfect one, and a crap one, with nothing in between. As soon as a bearing starts to wear, the deterioration thenceforth is relatively rapid. They are not like regular wear items which are designed to deteriorate (wear) from day one.
Obviously the higher the loading, the more rapid the deterioration and eventual destruction of the bearing once there is an initial amount of wear.
However there is definitely a time window from the start of wear to total destruction. How long this is, is hard to tell, but I really don't think it's very long for an IMS bearing, considering the RPM.
Nevertheless this time window is the basis of how IMS guardian is supposed to work, by (literally) picking up fine pieces of metal in the engine oil and reporting their presence to the driver.
Another option I see, that may be more complicated and costly to develop, is to have some form of acoustic sensor and related circuitry that could listen to the no doubt specific noise made by a bearing on the way out.
That's how most pinking sensors work, so it's not Nasa - grade engineering.
Thanks, I understand that once a bearing starts to break up it can let go very shortly after, such is the nature of surface degradation with metal to metal contact. Any metal in the oil is a bad sign of things going wrong for sure.
What I was really driving at was can you actually hear any noises if it starts to fail, like say a clutch release bearing type of noise..?
Given what size the bearing is, and where it is in the engine, there's a lot of metal around it to sound proof any noises.
What I was really driving at was can you actually hear any noises if it starts to fail, like say a clutch release bearing type of noise..?
Given what size the bearing is, and where it is in the engine, there's a lot of metal around it to sound proof any noises.
Edited by RatBoy M3CSL on Sunday 8th September 17:03
With regard to your first question no bearing will last forever. It is a matter of time. But don't forget that no engine lasts forever either. Eventually, something on an engine fails and it goes. It's just that these engines seem to have at least 3 main design shortfalls that can lead to an earlier failure than is acceptable these days.
With the IMS, I understand that the main element is whether the oil finds its way into the bearing. They are sealed from new and lubed by grease. However, if the seal splits and oil finds its way in, this extends the life of the bearing.
It would seem to be a total lottery.
With the IMS, I understand that the main element is whether the oil finds its way into the bearing. They are sealed from new and lubed by grease. However, if the seal splits and oil finds its way in, this extends the life of the bearing.
It would seem to be a total lottery.
mollytherocker said:
But don't forget that no engine lasts forever either.
Yes no maybe, it's all do with with money, in the main.The problem is that ordinarily a well maintained engine will wear at a gradual rate, and in many cases, that wear is repairable at relatively reasonable cost. Admittedly it's getting more difficult nowadays, but older engines could be reconditioned back to as-new factory fresh clearances and performance more than once. Crankshafts, camshafts, bores, pistons, valve guides, valves, literally everything is regrindable / reboreable / replaceable.
IMS failure seem to me to be similar in effect to a cam belt failure, with added extras, but a cam belt failure is usually the result of neglect.
RatBoy M3CSL said:
Thanks, I understand that once a bearing starts to break up it can let go very shortly after, such is the nature of surface degradation with metal to metal contact. Any metal in the oil is a bad sign of things going wrong for sure.
What I was really driving at was can you actually hear any noises if it starts to fail, like say a clutch release bearing type of noise..?
Given what size the bearing is, and where it is in the engine, there's a lot of metal around it to sound proof any noises.
Some of the time there is noise which gives an early warning. The trouble is the noise may not be taken for what it means. This is not the fault of the driver. One does not buy a car like a Porsche with the foreknowledge he has to be able to recognize an IMS bearing failure noise at any time.What I was really driving at was can you actually hear any noises if it starts to fail, like say a clutch release bearing type of noise..?
Given what size the bearing is, and where it is in the engine, there's a lot of metal around it to sound proof any noises.
Edited by RatBoy M3CSL on Sunday 8th September 17:03
I have heard several car engines with what proved to be IMS bearing failure. The noise is not pleasant. It is clear -- granted I have some experience listening to engines -- the engine is not healthy and were it my car and its engine making that noise I'd turn the engine off ASAP.
But sometimes there is no noise. Or if there was it was not noticeable until the engine well, kind of exploded.
The other problem is the engine can make a noise that one might mistake for an IMS bearing failure, at least the early signs of it. My Boxster was making such a noise and I took off the serpentine belt and started the cold engine and let it idle to determine the noise was not coming from inside the engine (thank goodness!). It proved to be a bad water pump.
The bottom line is a driver might hear the bearing as it starts to fail, but he might not. The time duration can be short. Sometimes the engine can run minutes without getting worse. Other times the engine goes from noisy to well dead in just seconds.
I have to ask why do you ask?
Rockster said:
I have to ask why do you ask?
Why do I ask, curiosity really, I use my car daily, no noises, in fact it's the only 911 I've had which doesn't seem to use any oil, and its very well maintained.I'm aware of the IMS bearing risks and wanted to try and make sense of if there were any rules which may point to a mileage or a life span where the problem could develop.
Oh, and my buddy's 997 M97 just spat its balls out too which made me think..!
RatBoy M3CSL said:
Why do I ask, curiosity really, I use my car daily, no noises, in fact it's the only 911 I've had which doesn't seem to use any oil, and its very well maintained.
I'm aware of the IMS bearing risks and wanted to try and make sense of if there were any rules which may point to a mileage or a life span where the problem could develop.
Oh, and my buddy's 997 M97 just spat its balls out too which made me think..!
Daily driver?I'm aware of the IMS bearing risks and wanted to try and make sense of if there were any rules which may point to a mileage or a life span where the problem could develop.
Oh, and my buddy's 997 M97 just spat its balls out too which made me think..!
Well maintained?
Describes my 02 Boxster.
With 271K miles on its original engine, IMS bearing, even clutch.
There we go then, some of these engines do go on and on, it seems to be as total lottery if and when it might fail, I don't worry about it, just drive it and look after it.
However I do have to say it's piss poor advert for Porsche that this is so well documented now, what with so many manufacturers now giving 100K miles and 7 year warranties on their £12-20K cars.
OK so my old 4S was never a GT car or an uber expensive one, but it still cost someone £75K new which is a fair chunk of cash for anyone to shell out on anything with only a 2 year factory warranty.
A bearing is a bearing, made by SKF/RHP/INA/Timkins or many others, it's a £20 part used by the million, perhaps made a special for a specific fitment, but the balls and the inner/outer races wont be anything unique just because it's a Porsche.
However I do have to say it's piss poor advert for Porsche that this is so well documented now, what with so many manufacturers now giving 100K miles and 7 year warranties on their £12-20K cars.
OK so my old 4S was never a GT car or an uber expensive one, but it still cost someone £75K new which is a fair chunk of cash for anyone to shell out on anything with only a 2 year factory warranty.
A bearing is a bearing, made by SKF/RHP/INA/Timkins or many others, it's a £20 part used by the million, perhaps made a special for a specific fitment, but the balls and the inner/outer races wont be anything unique just because it's a Porsche.
Gassing Station | Porsche General | Top of Page | What's New | My Stuff