Porsche Repair: 944S2 driveline noises, rear bearings, porsche specialist

Question
Hey Dave,

I have a 91 944 S2 with 75k miles.  I have two driveline noises that are driving me crazy.  The first can be heard clearly when taking off from a start.  It sounds like a sort of like "quisssshhh" and diminishes as the engine torque drops off.  It can be heard most prominently in 1st but can be heard in higher gears if I'm getting on it.  I used to have a 924 and an Audi Fox that both made this same sort of sound.  In both of those cars it was a bad bearing in the tranny.  I'm surprised that this bearing would go bad at 75k even though I know the car was driven in Porsche club track events by the previous owner.  Probably time for a rebuilt trans.  I dropped the trans oil and found a few metal particles in it.  There were two or three pieces that were about .020" in size but mostly very small stuff.  This noise has not gotten worse in the last 2000 miles.

The other noise is really vexing.  The noise occurs while cornering hard.  It doesn't make the noise until you build up enough cornering force and then the noise suddenly comes on.  There's a definite threshold.  Cornering even harder yet doesn't increase the noise significantly.  It does this in both directions but the threshold seems lower turning left.  It seems to be coming from the rear but its hard to tell.  A mechanic friend thought it sounded like something in the driveline is touching the body.  I've spent a couple of hours under the car looking for clues with an inspection mirror but can't find any telltale signs.

The Porsche dealership was no help.  The service manager rode in the car and announced dismissively that "a rear wheel bearing was bad" (I wasn't driving a rear engined car so he had a rather snobbish attitude).  After replacing both rear bearings it is still there.  And no, I did it right and did not brinnel the bearings putting them in.  

I took the car to a Porsche specialist repair shop and they didn't have any answers either.  They are in a downtown area and we could not find a place to corner the car hard enough to make the noise.

The two prior owners obviously loved this car and took excellent care of it.  Its totally original and looks brand new inside and out so I don't think it was thrashed too hard.  It had all repair records.

Have you heard of problems with the engine/driveline/tranny mounts failing that could cause this?

I am baffled and frustrated.  I bought the car a year ago and this noise didn't show up in the test drive because it only happens at fairly high cornering rates.  I got the car to enter club events and have some fun with it but I can't bear to corner it hard.  Until its fixed I have to drive it like an old lady.

Best regards,

Lance Nordby


Answer
Lance,

I'll be sending this same response twice.  As it turns out, your question was duplicated and sent to me twice.  If I don't answer each question, The AllExperts system will keep sending notices to me of an unanswered question.  Anyway, both answers will be identical.

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.

The interesting coindidence is that my daughter also owned a '91 S2 for about four years, and I cared for it for her.  I was always amazed at the power those little German engineers squeezed out of those four cylinders.

As far as the "quisssshhh" noise...that one I can't visualize (I'm sure there's a better word for imagining a sound someone else has made up a word for).  So, it seems your transmission bearing problem may be the right diagnosis, especially with your experiences with the other cars.

Your cornering noise is also going to be hard to pinpoint.  I never had the S2 at that cornering level, but I recently heard a bad new cornering sound of my own.  For my search, I'm going to be looking into the constant velocity joints...it seems like the joint components are being racked, or squashed toether, at unplanned angles.  This doesn't make too much sense, as  you'd imagine the joints being engineered to a higher standard than the car's cornering capability.  If it is, then I'm suspecting the joints may be at the early stages of failure.

This could be an area to look at.  And after you get that baby sorted out, I'll bet you have a great time racing it.

Dave