Intermediate shaft

[Aussiebox]

I recently bought a 97 Boxter with a broken engine - allegedly a broken timing belt. Rather than repair it I found a used motor (2.5L) and installed it. Before doing so I checked compression and replaced the IMS bearing. All good. It lasted 1 day, the timing went, the exhaust valves bounced off the pistons and bent open resulting in no compression etc. When I stripped it down I found that the sprockets on the IMS had moved on the shaft resulting in the cams going out of time. I later stripped the original motor and found the same problem with that shaft as well.
I have taken the shafts to my friendly machinist and he is going to pin all sprockets to the shaft for me.
I have not noticed that this is a common problem with this motor through my searches on the net and was wondering if others had experienced something similar.

[JFP in PA]

Originally Posted by Aussiebox

I recently bought a 97 Boxter with a broken engine - allegedly a broken timing belt. Rather than repair it I found a used motor (2.5L) and installed it. Before doing so I checked compression and replaced the IMS bearing. All good. It lasted 1 day, the timing went, the exhaust valves bounced off the pistons and bent open resulting in no compression etc. When I stripped it down I found that the sprockets on the IMS had moved on the shaft resulting in the cams going out of time. I later stripped the original motor and found the same problem with that shaft as well.
I have taken the shafts to my friendly machinist and he is going to pin all sprockets to the shaft for me.
I have not noticed that this is a common problem with this motor through my searches on the net and was wondering if others had experienced something similar.

Yes, it does happen. This is one reason you should never push on these sprockets while doing an IMS retrofit.