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THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHMy 99 IMS Bearing
Reported or suspected cause
usually slower in progression
Reported cause
No successful repair reported for this finding.
1
Identified cause
0
Suspected cause
0
Reported fixes
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Discussions that report identifying a cause
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Reported cause
The problem is usually slower in progression for the average Porsche M9X owner and doesn't have the quick death like IMS bearing failure.
Leading evidence: 'usually slower in progression' (1 discussions report identifying this cause; no attributable repair resolution). Across 1 matching discussions, the most frequently mentioned possible cause is 'usually slower in progression' (1 discussions; 1 report identifying it and 0 suggest it). The most frequently discussed action is 'Check grease is' (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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Discussions that performed work without a confirmed outcome
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Performed · outcome unconfirmed · Original poster
I just replaced my 99 IMS Bearing with the IMS solution so I wanted to share a few pictures of it.
Replace alphabet soup in his 02c2, at 16 years/46k miles
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Performed · outcome unconfirmed
(sincere questions from s1 who pre-emptively replaced the alphabet soup in his 02C2, at 16 years/46k 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.
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Performed · outcome unconfirmed
The answer was 1,600 miles from a Boxster owner that only used his car inside his golf club driving to and from the clubhouse.
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Suspected cause · Original poster
I thought it was RMS but I believe it was the IMS.
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Suggestion
Remember, the intermediate shaft is submerged in engine oil during normal operation which provides more than enough oil to cool and lubricate the IMS bearing."
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Suggestion
These components were never intended to be repair components, they were developed to be proactively installed as an elective procedure to engines with "perfectly fine original bearings" fitted to them as a service item.
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Suggestion
We've had truck repair shops, Midas muffler, and instant oil change businesses carry out this work as people search for the cheapest price to just have the bearing changed.
Outcome qualification: Negation, uncertainty or missing explicit repair resolution overrides the raw extraction signal.
Coverage and how to read this overview
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42 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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I just replaced my 99 IMS Bearing with the IMS solution so I wanted to share a few pictures of it. I know these are to have the lowest failure rate. I changed it out when I notice a small oil leak. I thought it was RMS but I believe it was the IMS.
The bearing feels good and smooth. Looks like some heat colorization but glad I got took care of it now.
Fascinating. I just scheduled an IMS bearing update for my early '99... looking forward to seeing the condition of the original bearing when it comes out.
Does looking for grease even make sense at this point after a bearing has been in use and submerged in oil for over 20 years? I feel like the grease is there as an early safety measure for when the car is new. After some time it probably gets washed out with oil and oil takes place as the lubricant. I'm just having a hard time visualizing how any grease can be expected to withstand hot oil for 20 years that is around the spinning bearing for so long. If someone could explain this I'm all ears! This is why frequent oil changes with a quality oil are so important. That and using your car as a car.
I've wondered the same thing. When I posted a picture of mine after replacement everyone said "pull the seals. Check for grease" uhh.. if it's functioning perfectly and constantly covered in fresh oil. What difference does it make? It didn't fail nor showed any signs of failure. I replaced it purely as a precautionary move.
They need to verify it hasn't failed and could've caused engine damage as a result. They don't want to warranty an engine failure if their bearing was installed on an already faulty engine.
That's because everyone just repeats the same thing that's been said before and never questioned. I'd still like to understand why I should expect to see grease in the bearing after 20 years of use.
As much as I understand that LN wants the bearing for warranty purposes and to ensure the bearing wasn't installed in a failing engine, isn't that what the pre-installation inspection is for. If installed by an authorized shop, they should be dropping the sump, inspecting filter, cam deviations etc. If that tells you the engine is cleared for the new IMS bearing, is the old bearing say something different? What if the engine cleared inspection but the bearing was showing signs of wear but there was no contamination from it... what happens to the warranty there if the LN bearing did fail? Just a genuine question because we have an owner in our 40AE registry who just lost his motor due to a failed IMS bearing. It had the LN IMS replacement done.
Yep
I sent mine in
Sadly my very expensive paper weight was in like new condition and now resides in the growing collection of our good friends LN
Mine might be exhibit A. A perfect, like new IMSB example pulled for no good reason
But, I never think about IMBS failure now. I am onto one of the other 51 failure modes to keep me up at night
How old was the bearing? Was it a single row pro, or classic single row? Was it a registered installation?
Collecting the old bearings is a way to confirm that the original bearing was not failing, shedding material into the rest of the engine to create collateral damage.
The only time that an engine is qualified for an IMS retrofit procedure is if the work is being done to a "perfectly healthy bearing". It the original bearing has begun to fail, the engine has already seen microscopic wear debris shed into the oil which has circulated through all internally lubricated components and has done some degree of collateral damage.The factory oil filter does a very poor job of collecting this debris. These components were never intended to be repair components, they were developed to be proactively installed as an elective procedure to engines with "perfectly fine original bearings" fitted to them as a service item. This is why each bearing has a specified service interval and has since 2008. The only exception to this is the IMS Solution, which has no load carrying moving parts, and all load is carried by the film of pressurized oil between the stationary inner journal, and the rotating bushing.
The IMS Retrofit became something that was so mainstream that normal shops that are not trained, Certified Installers were not following the pre-qualification process. Since they were not CFIs they had nothing to lose if an engine was already damaged and the IMSR was carried out. CFI's do have something to lose in this case.
We've had truck repair shops, Midas muffler, and instant oil change businesses carry out this work as people search for the cheapest price to just have the bearing changed. This is the main reason why the original bearing is required to complete a registration, it is a way to keep everyone in the chain honest and ensure the job is done is carried out as intended.
Even IMSRs that are carried out by CFI's have to follow this, but today over 60% of IMSR jobs are not carried out by a CFI. More CFIs are being trained at this time, but most shops can't meet the requirements.
The only reason to check for grease is to see if the bearing has been compromised. No grease, just oil means you are in stage 1 of bearing failure according to Jake Raby.
Asking questions is how I learn and saying "because Jake Raby said so" doesn't really answer them. Saying that you're in stage 1 of IMS failure because of no grease and just oil not only doesn't make sense but contradicts what is suggested about the larger IMS bearings used in later cars as well as the 997 cars. Straight from LN,
"When replacing the clutch or flywheel, the grease seal should be removed off the larger, non-serviceable IMS bearing to allow engine oil to better lubricate it. Remember, the intermediate shaft is submerged in engine oil during normal operation which provides more than enough oil to cool and lubricate the IMS bearing."
So, if oil is a suitable lubricant for basically everything else inside of the engine, and suggested as a lubricant of the larger IM S bearing, why is it not an appropriate lubricant for this one bearing, and specifically in the early 996 cars? Why are people looking for grease assuming it's better?
For the record, I'm not disputing or downplaying the fact that the IMS bearings fail. Clearly, they do and I have replaced mine when I purchased my car. What is just silly is that people repeat ridiculous things over and over as if it's gospel, like looking for grease in a 20yo bearing that sat in oil and spun at a high speed.
~%1 failure rate on dual rows, ~4% on single rows.
show me a one owner 996 that has been well cared for (and not tracked 10x/year) with a failed imsb (seriously�)
Lol yes I�ve seen the videos that make me hate my 996.
they�re good cars. Have said it a thousand times.
not even sure why imsb is still being talked about- I thought we were onto bore scoring???
I think this really depends how you define "well cared for". It seems like to most people that means not driving the car too hard, not tracking the car and following factory prescribed maintenance. In many cases (of course not all), the cars that had their bearings fail were low mile garage queens with an annual at best oil change and no track time. If someone did about 3k miles a year and subscribed to the 10k mile oil change interval was that car well cared for?
I think if everyone parroted 5k mile oil changes and driving your car regularly the IMS and bore scoring issue would not be what it is today. I'll use my car as an example vs GC996's car. According to my records the IMS took out the engine with just under 21k miles. According to the records, there were 2 or maybe 3 oil changes during that time/mileage. Highly doubt the car ever saw track time. GC996 has done more oil changes than most people on here. He also tracked his car - a lot. No bore scoring at all. Did the IMS as a preventative measure. Not saying frequent oil changes are a cure here but they are a bigger factor than most people think.
Videos that talk about modes of failure should not make you fear ownership, but rather, make you a more wise purchaser of these cars. Different way of looking at it. You ask any dealership these days and they'll admit that the average buyer is more educated about the good, bad, and ugly of the cars they want to purchase. I guess we should blame Al Gore for inventing the internet.
Now I'll agree with you about IMS bearing discussions. Because of the efforts of Jake Raby, PCA, and others groups, owners and prospective buyers know what they need to do about the problem. If they ignore it and have failure, then it's a "I told you so" situation for them. There are plenty of aftermarket products that can be installed that are better than the factory, especially if we're talking about the 6204 bearing cars. What I hate to see is someone that buys one of these M9X based cars and claims that IMS bearing failure and/or bore scoring are myths made up to make money for the aftermarket industry. That couldn't be further from the truth. Jake Raby has said that bore scoring was actually the #1 mode of failure that he began documenting on the M96 engine way before IMS bearing failure became a hot topic.
RE: bore scoring. The problem is usually slower in progression for the average Porsche M9X owner and doesn't have the quick death like IMS bearing failure. And it's often misdiagnosed as something else like failing lifters or misfires related to aging coil packs or spark plugs for example. Many people will continue to drive their cars with the problem until the misfires get so bad that they have to park the car. Before the awareness of bore scoring, many shops wouldn't even scope the cylinders. Now it's becoming a common practice with these cars. A lot has to do with awareness of the problem and education on how to solve it.
>>>
~%1 failure rate on dual rows, ~4% on single rows.
1 - 4% of what? There were about 175k 996 made. Are 1750 - 7000 IMSB failures likely to occur? Am I in the clear once that many have been achieved? As the population of (operable, un-retrofitted) 996 contracts, how/why is this..."statistic" to be applied? I feel like it tells me right next to nothing, yet it appears in 76% - 93% of IMSB threads.
Also: Porsche thought/pretended that the IMSB was a lifetime part. The aftermarket replacement is term/mileage limited. How is this an upgrade? Why is the upgraded part subject to routine replacement, when the OE part stands a "96-99%" chance of lasting as long as the rest of the engine does?
(sincere questions from s1 who pre-emptively replaced the alphabet soup in his 02C2, at 16 years/46k miles. Kept the perfect paperweight, buying another LN IMSB at every clutch replacement but my clutches tend to live long lives. 96.3% of the time!)
That is absolutely incorrect. The grease will stay in the bearing as long as the grease seals never shrink. The seals have nothing to do with keeping particles out.
Would love to see photographic evidence of this. LN should have thousands of bearings on hand that were returned as a part of their warranty process. We know that many are replaced as a proactive measure and came out in perfect shape. All it takes is a moment or two to pop off the seals and look for grease. Again, 15-20 years later, after sitting in hot oil, I doubt it's there.
Its academic if the grease seals work or not, it's impossible to make grease last 20+ years and millions of cycles.
there are lots of examples of sealed bearings being used where perhaps they shouldn't be. Just look at the pinion bearings in the gearbox that also fail.
I used to have a bmw motorcycle that had the same thing, a sealed bearing inside the gearbox which is full of gear oil, it would fail in the same way.
The only reason I can think of why engineers put these things in is they listen to bearing vendors who wow them with lots of reliability data and promises that if they use their bearings they won't have any problems.....and they have no time or resources to do their own reliability data collection, management tells them to put the bearing in and move on to other work
Yet some of these bearings seem to last forever. I bet it has to do with the fit. A bearing that is pressed in to a too tight fit feels crunchy....and it could be 10ths of a thousandths is all it takes
I think it all comes down to proper lubrication of the bearing. Once the originally supplied grease is gone and oil takes over as a lubricant, it's crucial to have the oil as in good shape as you can. This is why I harp on those 5k oil change intervals. Once oil ages and starts to oxidize is when you run into issues. When oil starts to oxidize, i
t causes a chemical change that often results in
oil thickening, formation of sludge and deposits, depletion of additives, and accelerated degradation
. None of this is good for a bearing and will cause it to wear.
Quick question for the experts...
So, if a imsb comes out feeling no ruff spots, spins smooth and tight, feels perfect. But with grease seal removed very little or no grease present. Careful inspection shows *****/race have no heat bluing, no galling no fretting. Cleaning with brake clean on a white clean paper towel shows no debris, no metal flakes, no particles even looking with loop.
So the above is stage 1 bearing failure(?) that does not allow a new imsb to be installed...?
Sorry, I don’t have any hard data. If the bearing/seals were engineered correctly to accommodate for load and sustained engine temperatures we probably would have minimal bearing failures. As I recall, the bearing Porsche used was at the upper-end of the recommended heat range specified by the bearing manufacturer.
Also, since the bearing seals are made from polymers, they will inadvertently fail over time due to shrinkage as this is a physical characteristic of polymers in general when subjected to heat.
I asked Mr. Raby about this. He said that he's seen a single IMSB that still had grease remaining inside it. The car/ engine had 1,600 miles on it at the time the IMS Retrofit was carried out.
I asked him what's the lowest mileage IMSB failure he had seen. The answer was 1,600 miles from a Boxster owner that only used his car inside his golf club driving to and from the clubhouse.
That car likely never had an oil service performed, so who really knows.
Extended oil service intervals played a huge role in the seal failures/ shrinkage.
The reasons why the sealed bearing was utilized was the favorable changes that it allowed to be made to the crankcase, making the casting easier to make, and cheaper as well. The Mezger engine uses plain bearings like the IMS Solution, but the crankcase has internal oil galleries that are drilled into it to allow for the pressurized oil to reach the plain bearings. Cutting out all these steps made the M9X crankcase housing significantly simpler to cast and machine than the Mezger.
