To IMS or not to IMS with clutch replacement
 

My '98 986 Boxster with 108k+ miles needs a clutch.

I know that when you do the clutch you should also do the IMS and RMS.

My mechanic says that if the IMS has not failed yet to leave it alone.

This car likely has the double row bearing.

I'm not interested in spending more than I have to so not doing the IMS will save some $$.

Thoughts?

My throughs about this is that if the car is in good shape, is babied, and you intend to keep the car, and adress issues as they arise, i would do it.

I'm going to do the clutch on mine and will do ims and variocam pads at the same time. Variocam pads are surely a wear item and guaranteed to be worn at that milage. Finding brown plastic pieces in the oil filter is a sign they are on the way out.

The real cost here is work, getting the transmission off, and changing clutch. The ims job is pretty quick. Imsb part itself can also be a considerable cost depending on what you change to. If you change to an open bearing, its important to check the oil and oil filter for debris to make sure the engine is in a good state.

My Porsche Dealership never touches the IMS, even if they have to do major stuff, dropping the engine, replacing parts and repairing what not, not to forget charging me major $$$$.
As they say, if there is no sign of failure, don't touch it.

My impression of this is that porsche themselves only "half-ass" acknowledge that the ISMB is a problem. They had to be forced through a a mass lawsuit in the US to even bring out some numbers of failure. In the EU i feel they kinda try to sweep it under the rug still.

It's up to each owner of these now old cars to decide if they feel lucky or not. I'm not usually the lucky kind, so i'm changing mine for sure.

If you go back to the lawsuit and the percentage of failures Porsche admitted to, then add that there may have been an equal number they didn't know about, add in the fact that the cars are now lots older than they were then ... now what do you think the odds are. And more what do you lose if it does start to go. Price an engine.

OTOH, last I heard there were 28 points of failure identified by one shop. So the IMS is only one cause but the failure can exhibit in multiple ways and only some caused by the IMS.

As for the opinion of the dealer, they only want to stick with Porsche supplied parts for liability reasons. They don't want to deal with a part a customer brings in to them lest it because an argument of failed part or improper installation..

IDK,..But for me, I would change or update it ,it's right there, a good quality Bearing and NO second guessing,.If your Mech. is wrong who pay's the price for it, That's how I see it ,.GL Frank

Here, many dealer actually install LN Engineering retrofits, having learned their lessons from the class action lawsuit an PR issues associated with the IMS failures.

I read somewhere there's a school of thought that the way some halves were machined can cause IMSB failures and that if it hasn't failed after so many miles, then the probability of failure is low. I don't subscribe to it, I only mention it as the only possible justification for your what mechanic said.

Like everyone here advised, I would replace it if I were in your shoes and "in there" already. From what I understand, by the time you realize it's bad it's too late. I'd replace the bearing with the same one as the original. It lasted you this long, there's no reason a new one shouldn't last just as long or close to it. If you need help finding the same style bearing, youtube "burner's cars". He has a series of videos on this and considered several kinds of bearings before settling on his choice, and he gives some solid reasoning behind his decision. He also tells you where he sourced his, and it was VERY reasonably priced.

Here's the link to Burner's video I was referring to:
https://www.youtube.com/watch?v=IxdvSq_byZw&list=PLiya6G1pHhIYyzhlVzS_LwoI ovrlv6_lv&index=16

And here's the link to the bearing specs: (Burner decided not to post his source, but instead posted specs and requirements)
https://burnerscars.blogspot.com/2016/08/sourcing-your-own-porsche-ims-bearing.html

I think you are referring to the RMS seal failure issue, which was the result of two failure types:

1. The original seal was a Viton based unit that did not have the life expectancy and was replaced by a PTFE based seal, which worked.
2. Out of round case openings which would leak regardless of the seal material used. These were the result of machining issues and Porsche released a "concentricity" test tool that was a go/no go test that was used if the engine was still under warranty; if it failed, the engine was replaced as it could not be corrected in the car.

There was also a non concentric IMS shaft problem, where the shaft would wobble because the IMS bearing center line the the shaft center line were not the same. This was mostly in the early 986 engines and was enoght of a problem that engine rebuilders had problems finding enough usable shafts to reassemble the engines, but that had nothing to do with the engine cases, it was a shaft assembly problem.

I may have gotten those issues mixed up, then. Thanks for the clarification. In that case, I see no justification for the advice that mechanic gave pianoporsche.

There is also the alternative of inspection the IMSB, by removing the flange. If it is OK remove the bearing seal and put it back together. I did this on 2 engines. Best to lock the camshafts before removing the flange.

Isn't it hard to get a accurate assessment on the condition of a bearing if you can't spin it? It's not like you can get a decent look at the races, can you?

I just had a major service done my car has 57000 Km it had the IMS kit installed when I bought, however the mechanic did recommend the RMS be addressed mostly because I had developed oil leaks. I had him do the clutch, as the previous owner did not. In my case I did have some seepage on the RMS seal.

But after reader many post on a car with lots of miles and the IMS hasn't failed probably not going to as the fell rate was very small percentage and the failure occurred early on, however as mentioned if your keeping the car and make you sleep better then get it done will you have the clutch installed will save on labor cost.

With the flange off you can spin the bearing and with the seal removed you can see the condition of the balls and races and if there is grease or oil present.
I offer this purely as a possible alternative, not everyone would feel at ease with this way of proceeding.

OK got it, thanks.

i totally agree with this , if they start checking them and suggesting changing... they are openly admitting its an issue which they have never done.. But they did quietly introduce the IMSB as a replaceable part..
I would NEVER believe what Porsche says about this issue ... its because of them that so many owners needlessly suffered...

The first " sign of failure" is your engine grenading as its absolutely absurd they expect owners to cut the oil filter open and have oil analysis every oil change....

Stop listening to one of the most successful marketing companies in the world and wake up to the reality these things fail at ANY mileage.

if you are right there and dont even look at it .. you only have your own ignorance to blame.

just my 02c