Welcome to the forum Peelyj.
The reason you're not getting a lot of response to your question is because this topic has been beaten to a very small pulp. There's volumes of info out there if you search on IMS. But here's the Reader's Digest version (if you get that reference you're old):
97-99 had a double row IMS bearing. Fairly reliable with approx a 5% chc of failure. Engine blocks in 99 had a chc of getting D Chunks, which meant a portion of the cyl could fall out. But by now those engines have been replaced or destroyed. These bearings are referred to as Gen I.
00-04 changed to a single row IMS bearing. Failure rate estimated at 10%. But a 2000 model yr car could have a Gen I or II bearing. There is no particular cutoff date when the switch occurred. The only sure thing is if you have an early production car, it'll have a Gen I and if it's a late production 2000 it'll be a Gen II.
05-08 changed to a larger single row IMS, known as Gen III. Failure rate est at 1%. Porsche pulled their usual monkey business by making the change to Gen III mid yr of the 2005 model yr. So early 05s still have the Gen II IMS, middle production cars can be either or, and lates are Gen III. While Gen I & II IMSs are replacable, Gen III is only able to be replaced if you tear the engine apart and break the engine halves. So it's very hard to replace but has the least chc of failure.
It basically comes down to how much risk you're willing to take. If a 97-04 car hasn't had the IMS changed by now (replacement IMSs have been avail for almost 15 yrs), it should probably be changed. Then you have to decide if you can't take the risk to even get it home, or you can wait until the clutch needs replacing and do it then. Or you can ignore all the IMS hype and not change it at all. Everyone has their own levels of risk. Just don't complain if your luck runs out when being proactive was an option.
Something else to consider - as mentioned above, replacement IMSs have been around for a long time. Some of the early ones were limited in their projected lifetime and may be to the pt where they now need replacing. "Permanent" replacements have only been in the mkt for the last 5-7 yrs. Not much discussion about replacing the replacement, but the early ones weren't meant to be the last one.
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Last edited by husker boxster; 11-09-2023 at 06:06 AM.
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