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BarryL
MarkW's quote that there are 20+ other major things that can go wrong with the engine, so putting a lot of money into replacing IMS may not be worth it for a high mileage car resonated with me
That is not what I said.
First a bit of background:
A noted Porsche engine builder has offered there are a number of failure modes for these engines. I do not know what number he is currently up to but "32" sounds about right. This is right and wrong. Right in that given a large enough population of engines a number of different failures will occur over time.
Given the engine builder is in the business and sees a number of sick engines I'm sure he has seen 32 different failure modes.
The more frequent ones, like IMSB, to the less frequent ones, like a failed crankshaft, all the way down to the one in a million failures. Essentially every critical compoent represents a potential failure point and with enough cars on the road then this just adds to the failure mode count.
But it is wrong in that the majority of engines do not suffer from any of these failures. Thus the "32" failure modes number is to me a bit of scare mongering.
And it was in this context, what I was referring to when I offered up the quote of the number of other major things that can go wrong is in some way when you take care of the #1 problem the #2 problem gets elevated to the #1 problem. Thus if one does go ahead with the IMSB upgrade there are still any number -- I think I said "32" not "20" but no matter -- of failure modes anyone of which can be as fatal to the engine as the IMSB.
But each owner has to decide what's his comfort level regarding risk and if he deems going ahead with an IMSB upgrade or even more upgrades to possibly/probably improve the odds at least the upgraded item(s) will not fail then that's the owner's call.