Another IMS question :-(

[thstone]

With 150,000km (~90K miles), the engine is well past the early IMS failure period. At his point, engine longevity will depend on regular wear/tear and how well the engine was maintained prior to your ownership.

There is no technical evaluation that can be done to help owners decide whether to replace the IMSB or not. It is up to every owner to make that decision for themselves without having any real data to go on. So, if the IMS really worries you or you simply can't afford or stand to have the engine fail for that reason, then have it replaced. But in general there isn't anything in particular to worry about at this point.

There are a lot of high mileage M96 engines out there still running on their original IMS bearings. For example, I had a Boxster that went 146,000 miles when the engine failed due to a lifter; another Boxster went 204,000 miles before a cam chain failed; and a 996 that was still running strong with 148,000 miles when I sold it. All had original IMS bearings.

Only replace the RMS if its leaking a lot. A few drips or two can usually be tolerated until the clutch needs replacement and then do the RMS at that time.