Boxster 986 - questions

[thstone]

Originally Posted by monopola

6. IMS bearing – guys, what is this ☹

In many engines, the crankshaft drives the camshafts directly (by gear, belt, or chain). In the M96 and M97 Porsche flat-six cylinder engines, there is an "intermediate" shaft which is driven by the crankshaft. The intermediate shaft then uses timing chains to drive the camshafts.

The intermediate shaft has a bearing on one end which can fail. When the bearing fails, the engine loses timing and the valves can hit the pistons and the engine can be catastrophically damaged.

There is a lot of info on this issue. There is no right or wrong answer. You will have to spend some time to learn about it. You will find some misinformation, a lot of anecdotal statements, even more personal opinions, and a few known facts. Then you'll have to make your own decision as to whether it is something that needs to be replaced or not.

[husker boxster]

Originally Posted by thstone

In many engines, the crankshaft drives the camshafts directly (by gear, belt, or chain). In the M96 and M97 Porsche flat-six cylinder engines, there is an "intermediate" shaft which is driven by the crankshaft. The intermediate shaft then uses timing chains to drive the camshafts.

The intermediate shaft has a bearing on one end which can fail. When the bearing fails, the engine loses timing and the valves can hit the pistons and the engine can be catastrophically damaged.

There is a lot of info on this issue. There is no right or wrong answer. You will have to spend some time to learn about it. You will find some misinformation, a lot of anecdotal statements, even more personal opinions, and a few known facts. Then you'll have to make your own decision as to whether it is something that needs to be replaced or not.

Excellent description that should make its way into a sticky.