IMSB Failure of an updated LN bearing

Hi all. I am close to purchasing a really nice 2002 C4S. History: IMS failure around 30k miles with a complete engine rebuild and replacement of IMSB with LN ceramic bearings. Recently, I was speaking to a friend who rebuilds these engines. He is a dealer and just purchased 2 cars with engine failures, to restore. Both cars had already had the LN IMSB update and both cars suffered a failure those bearings and thus engine failure. I know there is no perfect fix but to date had not heard of a failure of the updated system. Has me rethinking the purchase of the aforementioned car. Any thoughts or experience with secondary failures? Many thanks!

Quotes source post: 16597169

How long were the bearings in? They recommend changing them every so many years.

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LN requires replacement. Of course! $$$$ They are over priced and it's not a solution , it's a temporary solution and don't trust the product enough. DOF is better in my eyes. Makes more sense than hype and advertising campaigns.

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No one claims a retrofit is a solution, it literally says on their site is a service interval item.

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Good chance the engine was not cleaned enough during the rebuild

Good chance the bearing was collateral damage from something else that failed.

To many stories of replacement IMSB's going into a non qualified engine. Contact LN to see if it was registered!

This isn't the first and won't be the last. There are many shops that claim they have "saved" their customer's engine after putting in one of our Retrofits once the factory bearing had failed. We see if almost daily. We flag suspect VIN numbers and record shop names carrying out these installations, but we never see any registrations from them for a reason. It doesn't matter what IMS bearing is used if the engine is already compromised. It's a matter of time before something takes out the engine, at which time it's always the IMS bearing's fault. Those owners often will sell their car to some unsuspecting buyer unaware of this issue and bang, then it's our fault. At this point every Classic Single Row bearing we ever made is past its service interval and we know that every serial number earlier than 10,000 regardless of which type it is are all past due for servicing. Many of these bearings have been in service years beyond what we recommended for service intervals. I'll remind everyone who wants to say our design is flawed that Porsche came out with their own replacement bearing a few years back. It too used a single row ceramic hybrid ball bearing, however they chose to use one with grease seals. What would have done us all a favor would have been if Porsche actually released a bulletin on how to install their bearing and when to service it, but they never did. The kit became unavailable shortly after it was introduced. Everything I've just said I've posted verbatim on countless other threads. Nothing new here. I will add that everything mechanical can fail. New matter how hard we try to make it indestructible, someone will figure out how to blow it up. Our competitors have had failures too, but far less as they have sold far less than what we have. If they say they have never had a failure, they just haven't sold enough yet.

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You can look it up right here: https://imsretrofit.com/ims-check/ Every bearing we receive we disassemble completely for inspection. We take pictures too and often get photos of blown apart bearings or bearings that are covered in glitter on the outside and inside, even though the shop knows there is no warranty. What we've had to do is actually send out written letters to customers when we receive these failed registrations and tell them there is no warranty. This often results in someone being pissed at us about their warranty, but it's not our responsibility or even in our ability to qualify every shop that does these installs and if the engine doesn't go through pre-qualification, how can we warranty anything put in. Most registrations come to us in envelopes without the bearing at all - we call these "flat bearings" and again, reach out to the shop and customer for the original bearing. Many never get back to us or are willing to send in their bearing. If you notice a common theme going on here is that every Tom, Dick, and Harry who calls themselves a "mechanic" who has an account with Worldpac, IMS/Parts Authority, Northside, or SSF Auto Parts can buy the tools and bearing kits and sell them to their customers. We have no mechanism by which to sell the wholesalers who not to sell these to or if they even are knowledgeable enough to work on a Porsche. We've seen registrations from engine dismantlers, muffler shops, body shops, etc. It if up to the consumer to make the decision who works on their Porsche and a good mechanic charges accordingly. Shopping this job out on price alone gets you someone who has found every corner to cut to maximize his profit at your expense. Failures are the end result.

Hi Charles, Thank you for your response. It was informative and helpful. Question Are you familiar with Tiger Motorsports Inc in Los Angeles and if so, would it (by your company's standards) be a qualified shop. Many thanks.

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6 posts - must be an expert I bet MAROON is your favorite color

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The things you learn (always too late, it seems for me) about the 996 IMS retrofit. Thought I knew what I was doing asking for receipts to prove that the IMS retrofit was done on the 2000 C4 Cab that I bought back on 8/30/2019. Was shown/given such receipts and "assumed" (bad word) that it was an LNE kit because an LNE part # was used. However, I just looked ALL OVER my car and there is no LNE IMS Retrofit serial number sticker to be found anywhere. So, no LNE warranty even if a real LNE retrofit kit was installed. Oh well . . . Just have to "hope" (another bad word) that whatever retrofit kit was install doesn't fail in the next 2 years when the warranty (if there were one) would expire. LOL! PS: I have a hard time accepting that an IMS replacement needs to be considered a regular maintenance/replacement item based on the estimated cost of that work at $3-5k. This just makes it more likely that I'll sell my 996 sooner than later just to avoid the need to spend that kind of $ just to keep the car. I like my 996 but I'm not so "in love" w/it that I'd throw that much more $ at it. I can buy a lot of other older sports cars w/o such concerns for the $15-20k that I should be able get back for it, as long as I don't wait too long to resell it.

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It depends on when the bearing was installed and by whom. I had the LNE bearing installed in my 2000 C2 Cab (dual row) about 9 years ago and I don't have a sticker and there is no record of it in LNE's database. I'll be taking it in shortly for replacement - only about 35k miles, but overdue time-wise. You probably do have an LNE bearing.

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Man you're on borrowed time, 9 years ago is a long time to roll the dice!

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Wouldn't that "just" be a 3 or 4 year roll of the dice? @wyovino , Are you considering going with another LN Engineering IMS, or the IMS Solution?

I don't think it's much of a gamble but I do plan to have it replaced with another LNE ceramic bearing this year. It's a dual row bearing and the original Porsche bearing was in perfect condition after eleven years and more miles. The suggested time for a dual row replacement is 7 years (I think) . My indy will insist on replacing the AOS at the same time. I'm still on the original AOS and I test it periodically with a manometer. I'd hate to replace a working AOS with a new one that fails in a year or two so I'm going to ask him to install the Ultimate AOS. This next bearing will likely outlive me. My car is a Tip so it requires the engine out for this service.

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If your AOS hasn't failed, then I would just do the atmospheric port work on it, and continue using it with the rest of the UAOS parts. Save yourself some money since you have to drop your engine for the IMS.

I did the manometer test at a good shop, tested fine.. 6 weeks later I have massive oil in the intake and a broken cylinder (Not torn down yet) The AOS is the love child of a grenade that had a illicit relationship with a roulette wheel.

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That sounds like a good plan.. I wouldn't ask an Indy to re-work the Atmospheric port unless they are already familiar with how the UAOS works,( they may not understand, unless they have read up on it ? ) I would suggest just getting the UAOS AND the re-worked AOS for your year model and ask them to install. much simpler that way. I think there are many more M96 failures that were due to AOS failures than were previously thought. Many of the "it just blew up" failures were probably from hydrolock, and just scrapped. I remember my first encounter with a failed AOS, back in the early 2000's. Car came into the Porsche dealership on the wrecker saying the engine started smoking terribly. The car was still under warranty either CPO Warranty of Porsche Factory warranty (can't remember which). Anyway the standard protocol for something like this was to contact " Porsche Hot Line" . They advised me to pull the throttle body and look for excessive oil pooling and report back. Then they told me to replace the complete engine with a Factory Complete engine fearing the oil pooling and possible hydrolock had done internal damage ( slightly bent rod /stress ect). I'd be willing to bet there are MANY more cases, although I have seen a lot survive the trauma, at least for a while.. The UAOS could have been a game changer, if I had invented it 20 years ago.

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LOL I'm sure you've explained this before, but I'm curious why you have a TIME expiration in addition to a mileage expiration. the metal doesn't break down with time. Is it because the lubricant breaks down over time, regardless of mileage?

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Time-in-service and miles driven are both well established parameters to predict the life of a mechanical component within a system. Doesn't matter if it's a timing chain, water pump, alternator, clutch, or IMS retrofit. TIME in service impacts the health of a dynamic component like a bearing. Therefore, manufacturers give out time figures to predict proper replacement intervals. This protects the owner as well as the shop that did the install and manufacturer of the part.

Have anyone done the life expectancy calculation(L10h...and it's variants.... L10skf) for the IMS bearing? I have and it's WAY longer (for the small 996.2 bearing) than what you would ever reasonably use the engine. It's definitely NOT under dimensioned, it dies because of debris and corrosion starting the 'eat-it-self-up' process. All retrofits that I have seen have NO seals, which is just doomed to fail way early.

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Yes. It's I posted the calculated L10 for the 6204 single row bearing many years ago (probably over a decade). A member of one of the forums used to work for one of the big bearing companies and was able to run the calculation. It came out at 90,000 miles. Lots of assumptions there though.

Would be intresseting to hear what input he used. Even in worst case I get +10000h but more realistically 30-50th....that is in worst case 600 000 miles if you drove at 60mph. I used to work for one of the big too. EDIT: this is for a 6204 with dubble seals pre-greased 'for-life'.

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What are y'all calculating for actual load pressure on the bearing?

Radial 400N, Axial 100N (axial just for good measure...it's a chain drive and should be avg 0) at 3500rpm. Standard clearance, temps at 100c for inner/outer race and assuming they used an appropriate grease.

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I'll keep looking, but I can't find the original calcs. It was printed out and it's somewhere safe. If I find that safe space, I'll share the results.

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I think a lot of the issues with the IMS bearing is the harmonic/vibrations from the valve spring action. On opening, the springs resist Cam rotation, and on closing , they accelerate Cam rotation. This causes vibration/harmonics in the chain that transmits directly to the bearing. At a particular RPM, the harmonics may be at a very damaging frequency to the bearing. If the bearing were mounted in the proper elasometer, it would negate/cancel the harmonic/vibrations.

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Spot on. Like I said, there are a lot of variables. Not to go down this rabbit hole again as we have done in so many past threads, the oil temperatures these engines experience in traffic in hot climates coupled with low surface speeds (average lifetime vehicle speed for a modern Porsche driven in mixed city/highway use is about 35 mph). Depending on how the owner drives and what RPM they shift at, the life of the bearing would vary greatly. The races and seals are rated for intermittent excursions to 250F, so engine temperature plays a big part. The seals get hard and brittle, allowing the grease to get washed out. Long drain intervals and crappy oil fill the IMS tube with contaminated oil that never drains out as it's submerged in oil. Poor fluid exchange results in the bearing being fed nastly dirty oil and not a whole lot of it. That's why we remove the grease seal. When we developed the IMS Solution, we discovered that most of the load was all concentrated in one spot on the journal - right where we put the oiling hole. Also, looking at how the factory bearings wear, it would appear the ***** eventually flat spot and drag, again, all in one area on on the inner race, again, aligned where we found wear on our early IMS Solution prototypes. NVH I think is a big killer. The chain tensioner also puts a hell of a lot of tension on the ims to crank chain. It's sitting there with a load on one ball 24/7 even if the engine if off. When the tensioners get weak or the chains stretch, you end up hearing that rattle noise at startup. That's like a little jackhammer on the bearing. I could go on and on, but again, there are countless things that can affect the bearing that as a manufacturer you can't control. Lastly, engine speed

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Exactly, I think the main reason the IMSS works so well is large load area with the oil film cushion dampens/absorbs the vibration/harmonics VERY well..

Hold on boys and start thinking a little logical. IF there was an inherent error in the system we would see a consistent failure in the majority of engines, but we don't. The failures are random more or less(regarding milage/time)...hence the 'no one is safe'. Remember, most engines DON'T have an issue with the bearing. As long as there is no debris, good lubrication(quality and temp) and no corrosion the bearing life time calc will work fine. If one of those go **** you eat up the bearing before the calculated time. Remember, a ball bearing is more sensitive to this in comparisons to a plain bearing. For me the culprit is neglected service(change oil before it becomes too contaminated or acid), running too hot(coolant over 95c) and dirty air entering the crank case. Dirty air coming from vacuum leaks and stupid 'high flow' sport air filters, bringing debris into the crank case.

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You are totally disregarding the power and inconsistency of harmonic vibration, big mistake IMHO. I have spent countless hours dealing with harmonic vibrations in the 80's on a 525hp 12k RPM in-line 4 cylinder engine , that has the highest degree of harmonic vibration of any engine design. Every material/design has its frequency that it oscillates/reacts to. The harder the material the more quickly/violently it reacts once the frequency is hit. (everyone has seen the effects of a crystal wine glass hit with the exact damaging frequency by an Opra singer)..These reactions, to a much lesser degree of magnitude, happen all the time in engines.When problems arise from these frequencies, the solution is to change the design or the material( change the note sung by the Opra singer or change the material of the wine glass).Some of these oscillations take time to build (frequency (rpm) has to be held steady for a period of time). So the fact that the 6204 bearing design is the most effected, and the fact that it can happen at different mileages on different cars driven in different habits (rpms), fits precisely into the failure analysis of " harmonic frequency damage". I could go on and on about what I learned from the 525hp 12k rpm in-line 4, but just to say Charles and I agree, harmonic vibration is a BIG Killer..

Harmonic vibration need to come from somewhere, right. In car engines we usually find that the crank starts twisting at the right frequency and maybe breaks. Let's for a second just assume that the cam shafts also could start twisting in the same fashion. How would this affect the bearing? Well, due to the chain drive there would be a rapid acceleration - deacceleration rotational motion on the IMS shaft, around 300-400hz. This would translate to a radial load change on the IMS bearing with the same frequency. Now, what ever load affects the IMS bearing would need to be received/transmitted thru the chains. So, if you heavily load the IMS bearing it means that you need a lot of force thru the chains and in turn putting a serious load on the cam shaft bearings also. It would in turn also put serious load on the IMSB flange. IF there was strong harmonic vibration I would assume other things to fail before the IMS bearing. Then, you need to wrap your head around how strong the 6204 really is. This bearing is commonly also used in motorcyles as wheel bearings.....at the back wheel....on the sprocket side....of +100hp motorcyles. What do you think the radial force is when you ride at high speed down a bumpy road? Chain drive force + weight + dynamic load. And your trying to tell me that the same bearing spinning some cam shafts(in low single digit hp) would be overloaded?

I'll just add some data points here. Porsche put out a bulletin years ago that a single mass flywheel would void the warranty, granted this was with the Mezger engine. Also, we've seen countless M96/M97 engines have catastrophic crankshaft failures with single mass flywheels. Lastly., putting even semi-solid engine and trans mounts together transfers enough noise to pull significant timing out of the engine. Looking back at the class action lawsuit data, all things equal (sealed factory bearing) with similar operating conditions, the single row had a much higher failure rate reported under warranty of 8% vs. 1% for the dual row. Load rating and bearing type (deep groove ball bearing for the single row vs angular contact for the dual row) are the only differences here). I think surface speed also has a lot of influence here and that's why Porsche went with the 6305 which gave additional load capacity matching the original dual row with a larger diameter that increased the surface speed. The bearing is going much slower than crank speed and I do believe that low average bearing surface speed coupled with the loads explains why cars that are driven harder (rpms kept up) and tracked don't seem to have IMS bearing failures or at least as often, which was an observation we all made years ago.

Quotes source post: 16605361

^^^Yeah, we all know what �life� means when it comes to IMS bearings and engine coolant...🙄🙄🤣

Your reading and interpretation of the lawsuit I don't agree on. It was never a 'single-row' lawsuit, it was a 996.2 engine failure suit. IF it was a single-row lawsuit I would expect it to say "all m96/03 engines including m96/04 with single row" but it doesn't. It list specific VIN number ranges in the m96/03 range, m96/04 was completely excluded. Ever wondered why? It clearly indicates that it was not a design problem but an identification of bad parts used....bad quality bearings. That's why they never released a replacement bearing(expect for a short misstake a few years ago) or upgraded parts like is common, because it's nothing wrong in the design. If you look at it this way there is no need to start retrofitting perfectly fine bearings, it will just cause more problems letting hundreds of car mechanics trying to retrofit IMS bearings. The most efficient and economical way(for Porsche and the owner collective...not for the unlucky single owner) is to let the engines with bad bearings fail and replace the whole engine. But, they learnt from this failure and put a bigger bearing in the later engine which can survive a little longer even if it is bad quality. Maybe something they learnt from Toyota? As you say, it will be less loaded and will last longer(all things equal) than the 6204. Why do tracked cars seam to be fine? I think it's because they take care of temperature, change oil+filter more frequently and tend to use the correct oil. As a datapoint: The 6204 IMS bearing works well with 5w40 oil or thicker. If there is enough leak to flush out the grease, there is enough leak to oil-lubricate it(they need very little lubrication).