annoying engine vibration
 

My 88 924s has had an engine vibration at two points- 1200-1400 rpm (minor) and 3000-3200 rpm (major) for several months now. The car wasn't running for a year before this and I can't remember it vibrating before that.

The balance shafts are on time for sure, and I just replaced motor mounts which smoothed out the whole rpm range, but did nothing to help the problem spots.

It happens with the clutch engaged or disengaged, and I had a friend hold his hand behind the muffler and feel for a miss, but the exhaust pulses feel quite smooth. Does anyone have an idea of what this could be? Possibly a damaged balance shaft?

Thanks for you input :)

Your balance shaft pulleys are on wrong. It's the only thing that will cause these vibrations.

Here's the clark's garage proceedure for checking that.

http://www.clarks-garage.com/shop-manual/eng-08.htm

I will have to check again. Thanks as always socal.

Use a piece of wire to probe for the key in the key way. Even if the O and U are in the correct orientation the key ways can be off a half turn.