There is constant talk and worry about various xMS failures, they being RMS and IMS. The RMS in my car was replace by Porsche under warranty some time ago, but the IMS was something I was totally, and blissfully unaware of, until mine failed.
My tale can be different from those of others as mine failed while the car was under idle, in an underground parking garage, which brought its own challenges. The humourous portion of the tale is that it failed in a highly public garage in one of Toronto's fancy neighbourhoods, and the car had to be pushed into a parking spot through a series of level changes, by me and my partner. My partner was dressed in a skirt and heels, and there was a portion of it when she couldn't turn the wheel, so I was 'driving' while she pushed. Nothing better than seeing a blonde in heels and skirt pushing a Porsche into a stall.....
To make a long story short, I had looked at a number of alternatives, including replacing the engine with a 3.2l and finally settled on having the engine removed and shipped somewhere for rebuilding, given that there are no rebuilders in Toronto. I asked my friendly neighbourhood mechanic to pull out the engine, crate it, and I more or less had a deal to get it new rebuild for around (if I recall correctly) US$8,000.00 (based on the engine core being useless), plus shipping, plus removing and reinstalling the engine -- I expected a bill of above $10,000.00. The mechanic pulled the engine out, and I suggested we pull off the heads. Turned out that the dreaded IMS failure had torn a chain, bent a few valves, and had a destroyed IMS.
The engine was pulled apart by my mechanic, new IMS shaft (the new one from Porsche with the sealed bearing), a bunch of valves, new chain, machining and replacing a few more worn parts, and the MAF sensor. In the end, the total bill was around $6,000.00, and the engine feels brand new. In fact, after cleaning the car, tightening a few areas, the car feels like it did when it was new.
So, for those of you fearing the worst in the case of an IMS failure, it's not always catastrophic. I'm sure it could have been much worse had the IMS failed when the engine was at redline, but before one thinks that all is lost...
By the way, my car is a '03 2.7l Boxster.