IMS - some years more prone than others?

Are all 996 years equally prone to the IMS issue? Also - in searching for a used 996 is there a point mileage wise where you would feel more confident that the car would already have had this occur if it was going to be an issue? Thanks. Mike

With the lack of real and verifiable information related to IMS failures it is a difficult question to answer. Porsche did change seals and bearing design over the life of the M96 engine, but it is hard to judge success. However I would suspect that later cars are perhaps less susceptible than earlier 99-01 cars. Perhaps Jake Raby has some data, but it would only be related to the sample of cars he has repaired.

please refer to the sticky at the top of the 996 main page

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LOL

My 2000 966 had a good bearing @ 90k.. just sayin'

Mine 'seems' to be fine at 53k miles on a MY99....

C4S or C4 cars in my observation.....2002-2006

You are saying those are MORE prone to have the issue? Interesting, that your observation is that the mk2's are more susceptible. Before I posted this question I tried some searches to see if there was a consensus or if there was a data compilation but have found none. Surely this exists.

na. no one ever has IMS issues.. Its very rare... A search will turn up nothing. any one of the cars with the IMS is at risk. My car went 103K with its original bearing. I changed it becasue I was scared of it and will do it again in 50 more K. I strongly feel the issue is more how the car is driven then what year it is.

I changed the hell outta mine

Just treat is as a wear item. Change it with your clutch. Find something else to fear. (Screaming....you mean I should flush my brakes every two years????? OMG OMG OMG The factory should protect us from this!!!!!)

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+1 James! it's a bearing....nothing more, nothing less...they wear out - replace it before it does then fear of coming into the corner without brakes is gone

Slipangle, why are you asking, are you in the market for one, or do you have one and if so which year do you have? I just got my car last week and had the same fears before buying, the one thing i can say after I bought mine and found out really how fun these things are to drive and own, I can tell you I haven't really been thinking about the IMS possible failure. What I did was get 5 more years on the warranty and I'm not really going to think about failure with this car, these cars are about success. IMHO.

Slipangle--sorry my answer seemed short. You are asking a decent question (for which Boundless information can be found with the search function)--which is inherently frustrating as people don't really know the cause (yet). No - one year does not seem more likely than another. But--the chance seems to go up with age. Some argue that the harder you run the car, the less likely it is to be a problem. But, to my knowlege, there is no real data to back that up. So....superstitions abound. One approach is, assume it has a chance of failure & allow for about $2700 in the price of a car to have the trans dropped, replace the clutch, RMS, IMS, AOS, etc., (PDQ) -- and figure you're good indefinitely. If you adhere to this, then there is rationale to avoid the last couple of years of the 996/997.1 when the bearing was modified so it can't be replaced without an engine teardown (you can verify the exact years). (Of course, you could hope that the last iteration wouldn't have problems -- but since no one seems to know why -- there is some logic to buying and older year and just managing it.) IMS issues aren't new. There were Porsche engines in the mid '70's that had similar problems. Other manufacturers have had issues with IMS's -- so, it's part of the general territory -- probably slightly more so in higher performance engines. The real problem is that this has been covered to the point of nauseum and we don't really know any more than when we started. Increasingly, there are aftermarket replacements. So, you may have to simply dump trying to analyze it, and just figure its maintenance into the cost of the car. (...which compared to many high performance cars, is nominal.)

You would think that the double row bearing that was used on the early cars (99-01) would be more robust than the single row bearings that were installed on the newer cars. That does not make sense to me, unless Porsche decided to save some money on a less expensive bearing. All things being equal (?) you would assume two rows of bearings would be better than one. In fact it sounds like an upgrade to me. Obviously things were not equal, either cost vs. design.

All years are susceptible to the IMS failure. We see the highest numbers of calls and cars in the 01-04 model years. We see failures from all years, but the 01-04 cars have a single row bearing, 1/2 as substantial as the earlier cars. All cars should see the IMSR procedure as an elective procedure, once it is no longer elective you have to worry about collateral damage and big issues that can be avoided. Honda engines lose timing belts and require a preventive at 60K, we see the highest number of failures at 27-47K miles, so its just another wear item that must be electively replaced.

The lower rate of failures on the double row bearing makes sense to me. Why in the world did Porsche go to a single row design? That's a small plus on the '99-00 cars.

any two row guys have IMS failure that posted? :O

The exact reason why the single row bearing was employed is not known, it could be: -Cost -Ease of extraction since it has an external snap ring instead of internal -This was changed when the IMS drive chain was updated to an internal toothed chain from a duplex style chain, perhaps they thought the drive loads would be less? There are lots of other possible reasons. One thing is for sure, the single row is 1/2 as substantial as the double row and they do fail more often.

Jake, the dual row replacement bearing you sell is a bit more money than the single row. Is your replacement dual row IMS bearing still a dual row bearing and that attributes to the price difference?

LN Engineering has become a bit of an expert in designing solutions for M96 issues.... There are good fixes available if, or when you have a need to for it... Hope you don't ever need this but this link can give you answers to some of your questions...i suggest LN Engineering products to my 986/987 & 996/997 customers. Chuck http://www.lnengineering.com/ims.html

Yes, the dual row bearing remains a dual row replacement.. We have worked for LN for over 13 years and the IMSR procedure, tools and components are a co-development between the two companies. I designed the current IMS bearing puller, it is simple and it works exceptionally well!

Ok this was a helpful discussion for me so thanks to all who responded constructively. After attempting to read through some of the search results, some of these posts helped make my thinking more clear. Yes, I'm looking for a car and obviously finding plenty - still undecided between a .2 996 or a 997 but making some progress. This issue was something I wanted to understand better.

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Just know that a newer (07 & above) 997.1 will have an IMS bearing that is unserviceable unless you split the engine case. It is easier to address the concern by purchasing an early 997 (2005) or a 996 as the IMS bearing can be replaced without removing and spliting the engine case.

From my reading, I have narrowed it down to this: School of Thought #1: do the IMSR procedure ASAP School of Thought #2: do the IMSR procedure when a clutch change is done School of Thought #3: ignore the IMS unless it fails My thinking is to follow #2, but my car is a Tiptronic so there won't be a clutch change in my future. Given that, I'm back to trying to figure out when would be a good time to do the procedure. Anyone have any thoughts on Tips?

Very good summary of the choices.. You must either do the procedure electively or just choose to ignore it.. Once something occurs you have to just deal with it and lots of collateral damage. I have to say the people that we deal with that know about the IMS failure and have it occur are MUCH more disheartened than those who have no idea about it and experience it. We haven't had an IMS bearing failure call this week so far, but we had one roll in last week from memphis DOA and have one on the way from S. Florida now that was called in last week as well.. I believe that we can save the S. Florida engine, it is at stage III failure and I don't believe collateral damage has occurred yet. This week has been all about cracked heads and those failures, two on site now and three others called in. They come in waves.

Jake; great comments and i know of your relationship with Charles (LN)...You guys do good work! We appreciate the team! Chuck

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Not sure how many miles you have on your car, but you might consider doing a bunch of preventative work at once and including the IMS bearing upgrade. It will be spendy, but there are certain things that are just going to fail on you eventually because of age and wear. If you plan to keep the car, maybe one big, expensive refreshing is worth it, and it spreads the cost of dropping the engine around a bit. Just coming up on two years for my LNE bearing upgrade, and I am very hard on my car. I was one who replaced it without any indication there was a problem, but then once we were inside discovered that it wasn't far off.

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Have the cracked heads been from pieces of the water pump impeller coming apart and creating hot spots or do you believe the cracks have another cause? My local indie mentioned that only the right side cylinder heads seem to crack. Do you agree? Thanks, Jim

Pieces of water pump impeller or RTV sealant from service work are often found inside the capillaries of the cylinder heads that have experienced cracks. We mill the areas open and increase the passage size before welding the area shut and reinforcing it. The 4-6 bank of cylinders do have more issues, but all the heads can crack, especially 2000 and 2001 models which are by far the worst for this mode of failure in both Boxster and 996 models. The 4-6 bank is at the end of the cooling system where the pressure is least and the debris can block passages easier. This side of the engine also runs the hottest. Remember, the coolant temperature sensor is in the cooling system, not at the cylinder heads! The coolant passing by the sensor is not a true indication of the temperature after the coolant has cooled the 4-6 bank of cylinders..

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23,000 miles. 9,000 miles in the last 11 months (since I bought it). It's due for an oil service at 25K. I'll probably do the 60K service at 30K, but otherwise, there is nothing major on the near horizon.

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Well, this is just one man's vote, and I don't mean to be cavalier with your money, but if it was me I'd do the upgrade. Your car was obviously chosen for its low mileage, and I assume you intend to get a lot of use out of it. Considered in those terms, the cost per mile or cost per year or whatever of the IMS bearing upgrade is low enough that you don't need to feel like a fool if the original one turns out to be fine. Pay it forward.