A few problems with what you are trying to figure out. 1) There is no way to physically inspect the IMSB, oil analysis and checking the filter at change intervals is about all you can do. 2) Same thing for a replacement bearing. 3) If the IMSB fails, it's usually with little or no notice so, could be "fine" now, boom one minute from now.

If your question really is, "Should I proactively replace my original IMSB for piece of mind?", well, like gnat said this is all covered by the search button.

However, you are 100% correct about gnat being on the Naughty List...

 

I am not trying to figure anything out....REALLY....I'm not.....I just wanted to hear about people's experience.....that is all. I have NO question...other than having people tell me what their replacement bearing has done and how it has acted.

I understand the complexity and danger of trying to determine the status of the IMBS, without removing it. Not even wondering that.....


The ONLY thing that might be of interest is the repeated failure rate of the IMBS, IF....and only If....the original was found to be bad and then it went KA-BOOM with the replacement bearing....BUT....that is not necessarily what is being focused on.

I guess.....one COULD ask...(but I am not asking it), is if you had a good bearing, replaced it with a certain solution....and then that solution went Ker-Powwww! What was that solution....

But I repeat...I just want to know people's experience that have replaced a good IMBS.....Good news is allowed......

 

[QUOTE=Gonzo911;13833702] If a replacement bearing fails, all you will learn is that the car was doomed to begin with, or the original bearing was already compromised.

QUOTE]

I don't think this is an accurate statement. If your original IMBS looked great with significant miles on it, with no wear issues, and your replacement fails....how does that mean your car was doomed to begin with?

 

Because you replaced a perfectly good bearing with a bad one. Or a bad installation. Point is, you won't really know.

 

+996,000

1. Not all cars that had an IMSB retrofit had a proper prequal done by a certified shop/tech.
2. There are at least 2 dozen more MOFs that causes CEF...which can rear its ugly head regardless of mileage. Yes, there are many more 996 "killers" out there
3. way too many variables in how a car is driven
4. not all owners use exactly the same oil
5. ad infinitum/ad nauseam


Above factors (and hundreds more) will EASILY quash any attempt to get usable data to be used as a baseline

 

The car I just bought is at 61k miles and drives great! I am not planning anything proactively. If it fails, it fails and I do an LS V8 swap.

 

Congratulations on not getting sarcasm

So says everyone that starts an IMSB thread with a low post count.

The reality is that the majority of the information you are asking for is indeed in all those other threads. You simply don't want to do the leg work and want us to instead hand it to you on a silver platter.

Of course in creating this thread instead of contributing something useful, you've instead contributed to the very clutter that you new posters complain about.

If you had instead compiled all the information and then presented it for comment, you'd get a more warm response. Instead, like all the others before you, you come with no new information to rehash the stuff that has been beat dead many times before and will unfortunately be repeated many times in the future.

 

Funny you say that as that is what started my search for a 996 roller originally.
LS swaps aren't cheap, especially if you contaminated the 996 cooling system.

 

An original IMSB that's lasted many miles, and is removed with no race erosion/ ball spalling is a great indication that the original engine, and IMS assembly didn't come with mis- machined dimensions/ runout.

This alone removes a tremendous amount of the variables associated with the things that kill IMS bearings.

 

This comment perfectly summarizes what you'll learn from intense reading of the stickies in this forum. This is what makes proof of a "good driver M96" engine.

But you have to spend the money/time to pull and replace the bearing (can't use old one again after pull) so it's a feel-good you have to pay for...

 

I replaced my IMSB at 101K miles, it seemed in Perfect condition. Then had no problems at all... until the motor imploded. Hope that adds some useful insight.

 

OP did you think this site was going to be warm and friendly and offer up help to other Porsche owners?
Or, did you think you would be berated and ridiculed for using a site that claims to be for the betterment and sharing of info would be more willing to insult you for trying to get info and be bettered? Well, just don't make that mistake ever again. Take a course on how to use this site and quit wasting our (his) time.
BTW, I understand your question and am glad you asked it. I believe the answer did not adequately exist on this site and still doesn't. More response could get a resolution.
Perhaps people who don't like your question should read it once and then not bother with it a second time much less a third and fourth. They have that choice.
Nice to have you aboard. This site has tons of info and advise just for the asking. Ask away.

 

I subscribe to my own thoughts and feelings on the subject and while my 996 is sold and I no longer carry the ims worry my thoughts still remain the same. How many engine have been "saved" from a perfectly good bearing? I'll bet hundreds have, in the end I always felt there was a good percentage of fear mongering involved in the aggressive marketing of these bearings. Also the worry is always did the mechanic screw it up and it's now going to fail when otherwise it was in perfect shape? Just too many arguments here to sleep well at night. In the end it I were shopping a 996 I would want one that was n untouched original. I don't subscribe to a lot of the BS "maintainence" items posted on here.

 

I considered the IMS replacement as part of the acquisition cost of the car. At the same time we were able to check a few other things and carry out some maintenance that would otherwise go unnoticed and undone. All positive in my opinion and not crazy for a 15 year old car that sat a lot during it's life. I now have a reliable crazy fun sports car that I will drive for years without worry. That is the essence of the IMS "issue" in my opinion. As to which one to do, when to do it, consider it a value proposition or smoke and mirrors from IMS replacement vendors is between you, your wallet and your opinion.

 

Same here...