IMS recommendation

Hello im sorry to bring up this dreadful subject but I could do with some advice. Im only replacing this as its getting a clutch flywheel chains etc when I put it in for its rebuild. My car is a 2002 C2 3.6 and I don't know what IMS bearing to purchase. there seems to be many options below. https://www.design911.com/Porsche/996--911--1997-05/996-C2-3-6L-09-01-2005/Replacement-Bearing/pt856_1748_2776_-cma81-cmo110-ct347/ does anyone know the pros and cons of which one to go with? thank you in advance

I went with the EPS version when the clutch was changed at 31k as it was fit and forget (neither really needed to be done but the engine and box were out as the brake pipes needed doing but the car is keeper so i decided while they were on the bench i may as well) Its done 10k since with no issue............on inspection the original bearing was in near perfect condition. There is a school of thought that if there is no play in the original bearing then remove the oil seal to allow the engine oil to lubricate (if you search the web there is loads of information) All the best Andy

Hi Scott I had a double row LN ceramic on fitted to mine in 2014, since then the Cylindrical Bearing one and other types have come out. The cylindrical one looks quite impressive and I think that’s the one I would personally go for. But I’m sure others will have their own opinions. Odds on you will need to get the single row type but always check the engine number with the supplier to confirm. Good luck Andy

thank you very much for the I think that confirms my theory that they all pretty solve the problem. The reality is with my usage if it see's 10k in 3 years it will be a a busy 3 years so the cylindrical bearing will be more than up to the job.

Thanks for the reply Trevor, I think that EPS kit seems the most straight forward so far. I did a clutch and flywheel on my 987 Boxster S. That car had a internal bearing so was nothing to worry about. The scored 107k 996 is a different matter! That needs a clutch doing 100% the peddle is so heavy compared to the fresh kit in the 987. I think ill collect those early in the new year.

Hi Recently had my IMS done being an engineer I studied the different options. Didn't like the ball bearing LN version as they specify you need to check it every 4 years and for me that's about 8000 miles. I was looking for a fit and forget solution. Didn't like the idea of a permanent oil feed solution as the pipe is on the bottom and could theoretically be ripped off or they require connecting into other parts of the oil feed system. In the end I went for the EPS solution which is a theoretical permanent fix without the pressurized oil feed. The bearing is submerged in oil any way. This is a roller rather than ball solution and has no axial loading on the bearing. I also had a new RMS (Not actually leaking and clutch as it was nearly down on the rivets). The IMS bearing removed was in perfect condition, Both seals in place and runs as smooth as a babies bum. No play in it whatsoever. Car is a single row 2002 C2 with 47,000 miles at the time of fitting and full history. I also had a lower temperature thermostat fitted to reduce the risk of bore scoring. So why did I have it done? Every time I took the car out I was always relieved to get it home without it going bang, I knew it was unlikely but it was always in the back of my mind. (Didn’t think it would bother me when I bought it) Now 3000 miles on the car seems so much more enjoyable. Silly I know but the brain plays funny tricks. Yes, I could be unlucky, and the new bearing could fail but at least I have done due diligence. I expect you’re interested in cost under £1,700 including the clutch and VAT and the drilling out of a broken bolt. OEM parts used except the IMS and Thermostat of course. This article is not meant to be a recommendation just an explanation of my thought process Trevor

Is there any evidence that any of these bearings last longer than the factory installed one or have a lower failure rate?

I’ve read reports of the LN bearing failing, I believe these were initially marketed as ‘fit & forget’.

Indeed. When the IMS bearing were first reported to fail and all these companies started making alternatives, there was a big multi page debate as to whether these alternatives are in fact better than just sticking with the original. LN thought it was fit and finish, then some failed, then they gave it a 4 year guarantee. So every 4 years you have to pay to replace it (guaranteed cost) when the failure rate of the OEM IMS is around 5%. Why is that a better deal? That’s with an established IMS replacement company. Who knows the stats for any other company? People have been fitting these bearings from whichever company thinking ’That’s it, I can feel secure now’. Based on what statistics? I’m not saying they aren’t a better alternative, I’m just saying I haven’t seen the (non-anecdotal) evidence to prove it.

Hi All Good debate. To me the EPS makes sense when you read the theory on loading and the fact they are roller rather than ball. In addition it is an open bearing so naturally gets oil. In theory its should be fit and forget. But so are wheel bearings and they sometimes fail. I guess even if you replace it every four years at £1500 a time compared to a £15,000 engine rebuild you have 40 years + before you spend that much. I won't be around by then and doubt the car will be either but you never know. Happy New Year to all Trevor

For the purpose of this post I am after what people recommend. There is lots of threads about how the bearing fails and just as many of how they don’t. My car has done 107k and I will be replacing the part as part of the rebuild on the car. As well as the clutch, flywheel, water pump etc plus a lot of other parts that are likely to still have a life in them. At the moment I don’t see any negatives of using the EPS kit.

At 107k miles, there's more than the IMS that could go wrong. Bore scoring, D-chunking, rod bolts snapping, etc, etc. Not saying that these can go wrong, but they might . And to be honest, at some point something will . The M96 is what it is: a high performance engine containing flaws caused by Porsche's financial situation when it was designed. Eventually something will break. If you are really worried about the IMS failing, you might want to think about a pre-emptive engine rebuild. I had the IMS fail in my previous car, a 96k mile 2005 Boxster S, and decided to rebuild the engine. Not the best financial choice, but it noticeably improved the car's performance, not to mention that the engine got a bunch of reliability updates (e.g. big IMS bearing, ARP rod bolts, X51 oil pan baffle, etc). So the fun factor went up while the worry factor went down. FWIW, I have a 65k mile 996 now, and recently chose not to replace the IMS bearing when the clutch was replaced last year, just had the seal removed. It looks in good shape and I'm budgeting a Hartech rebuild in the next 2 years anyway, so for me it was a simple choice.

Thanks for the reply Gordy. You are quite right a lot more has gone wrong on this car! It still runs and drives but has confirmed bore scoring on 4 and 6 ! I am currently collecting parts ready for the rebuild later in the year. it's such a strange situation. On first start up one side is blue one is white. Plus smells of burning oil and sounds piston slappy. You can tell you shouldn't be using it. Once warm you would not know its broken no smoke barely any noise. Oil usage isn't that bad either. I owned it since December and done around 500 miles like it. If it breaks probably before the rebuild more fool me I have brought already timing chains & tensioners , Flywheel clutch slave, water pump expansion, every stupid nut bolt bracket for the exhaust. all the exhaust parts. coils plugs. and other bits which were probably expensive but i can't remember! The IMS part of it is just because it's being rebuilt. I will probably commit to the ARP bolts and X51 like you did.

Scott, Maybe I’m missing something here but if you have significant bore scoring I would have thought - while important - choice of IMS bearing would be the least of your worries! [ ] Good luck with the rebuild. Jeff

Scott, if have bore scoring issues then the engine will need a rebuild. In that case, you should consider the "final solution” IMS that Porsche introduced from 2006 onwards. This version is enormous compared to the single and dual row bearings in the 97-05 cars and is bulletproof. Unfortunately, it’s not fitted often because the bearing is so large you have to crack open the engine to put it and the IMS shaft in. At that point, the labor costs are so high you might as well do a rebuild, so it only becomes a real alternative when you’re rebuilding. Good luck with the rebuild. Are you doing it yourself?

Stay clear of the cast iron bore replacements - attractive on cost but introduce other issues. As these cars build mileage, the other issues are crank bearings scoring journals. Difficult to repair from what I've read on forums according to Hartech. On my rebuild I will be going for the Porsche IMS upgrade.

Finally someone with some logic. Jake Raby got so rich, people rushing out to replace perfectly good bearings in most cases, how many have since done replacements every 6 years. Like you said so many other things can cause serious engine problems on these cars. Jake Raby saw something he could earn lots of money from and he did (he didn't force anyone to change it) but he did plant the seed. I'm not saying the bearings in cars haven't been an issue, I'm saying it was never as big as made out to be. I'm still convinced that a car with a failing bearing should be able to be diagnosed because that bearing will be producing a harmonic, and test equipment is available to monitor this ( just not in the automotive world). This is also something that LN tried cashing in on by fitting a buzzer circuit looking for a resistance change in the circuit. Ridiculous because any form of metal debris in the engine would trigger the device, not just the bearing failing. Problem is when he marketed it he wouldn't tell anyone what it was or how it worked, instead he offered a free unit to anyone that guesses correctly, probably to keep them happy. Does anyone ever talk about these failed projects? No, so why would you put so much faith in one of his aftermarket bearing solutions, you could just buy any bearing, it will have been load tested as all are.

Any ideas on what kind of mileages the big end bearings can be good too? I know there are a lot of variables, so just wondering if anyone has any first hand experience. Thanks.

Gordy I’ve just purchased a 2006 cayman 3.4s. Do you happen to know when the "enormous " bearing was fitted and how you can find out what IMS bearing is fitted to the car. I’ve read so many articles that contradict themselves. thanks kevin500

Hi Kevin, yes I do. Porsche changed to the huge IMS bearing during 2005, so all 987s and 997s from 2006 onwards have one, including your Cayman. Good news for you! Some 2005 cars will have the huge bearing, and other than cracking open the engine the only way to tell is the month of manufacture and registration, the later in 2005 the better. My Boxster was built in January 2005 and registered in April the same year. If it had been September and December, I'd have been much more likely to have got the large bearing IMS.

Hi Gordy Thanks for confirming. I am a Porsche novice so any help with a Gen 1 Cayman 3.4S is much appreciated. The car has covered less than 30k. Ive read several articles that recommend the bearing seal is removed to aid lubrication of the IMS bearing. Is this something I should consider. Regards Kevin

You will be fine regarding the IMS. All Caymans have the final fix IMS bearing that is basically impossible to break, so I wouldn’t do anything to yours. That isn’t to say that the Cayman doesn’t have minor issues. D-chunking and bore scoping can occur, the RMS can leak, the con rod bolts can snap if you insist on visiting the redline on a regular basis and the engine will starve itself of oil if you explore the outer limits of the car’s lateral G capabilities. But that’s not to say that these things are likely. Caymans are very well sorted and if they haven’t been driven hard should be reliable.