QuestionI Own a 90 944 S2.Since I've owned it I always felt a vibration in the engine that I can feel at the shifter at around 3100 rpm.I have replaced the clutch,balanced the flywheel, checked the balancing shafts for correct installation,and rebuilt the torque tube. Have I overlooked anything? Can you suggest what I should do next? By the way after balancing the flywheel it made a substancial improvement. But it didn,t solve my problem. When I removed the belt cover and rev the engine to 3100 rpm.the belt vibrates as well.
Answer++++++++++++++
Ross, thanks for the feedback, it's very much appreciated.
As I'm sure you already know, the suggestion to 're-do' the timing and balance shaft sprockets, tighteners and tensioners is quite an undertaking. I'd want to make darn sure the belts are adjusted perfectly as they sit, before I attack the hardware. Any looseness that's not absorbed by the tennsioners could also contribute to your problem.
Just a bit more to think about...
You'd better keep going...I'll be watching!
Dave
++++++++++++++
Ross,
Just to remind you, my expertise lies in the older 356 models. Luckily, many early designs/concepts have lasted since the early 50's and appear in revised forms on 911's, 914's 944's, Boxsters, etc. Where this happens I'll promise to try to give you the best answer I can. Coincidentally, my daughter owned a '91 S2...and I got the "opportunity" to work on it quite a bit.
Boy, you've certainly worked this problem already. I do have a couple ideas for you.
The vibration of the Porsche rubberized belts is certainly inherent in their design, but I'd want to be certain the belts are new...but more importantly in your situation...the tensioning and idler pulleys and their shafts either need to be blueprinted or replaced. After all this, you may not get the smoothness you're after, but you'll know this component is a smooth as Porsche designed it.
The other avenue you might consider is checking the engine/transmission mounts. If worn, they could certainly cause the kind of problem you're experiencing. True, there's no connection to the mounts and 3100 rpm...but stranger things have happened.
When happy, these Porsche rockets really are a blast.
I hope you're able to get your beauty just where you want.
Dave
