makbloom

Any ideas what the problem is here? My 2001 996 C4 (tip) has a noticeable "whine" coming from somewhere. Does not happen under hard acceleration, or when coasting, but only when holding a normal fixed-speed/light acceleration. I notice it in 4th and 5th gear the most at about 47-50mph: That's when it is loudest.

If it is whining in 4th and I shift to 5th and don't accelerate, it keeps whining with no change. So in my mind it's not the engine since it seems to be rpm independant. So that leaves transmission, diffs, wheel bearings, etc.

Any ideas? Thanks in advance

JTT

This sounds a bit nuts, but have you tried turning off the AC to see if it changes? Mine was making a “whirring” sound, turned out to be in need of an AC recharge.

Mike Murphy

Could be the pinion gear, transmission, or a wheel bearing. When was the last time the diff oil was changed?

Edit: also check that it’s not coming from the radio speakers (alternator or bad ground), or from wind (a window or sunroof seal, a front cooling fan bearing, etc.)

makbloom

Just tried it.... unfortunately didn't make a change.

makbloom

Diff-oil was changed about 1 month ago, and there was no change before or after. There was a seal on the diff that was also replaced - there was a small leak.
I am fairly certain it is from the drivetrain. If I "flutter" the accelerator at 47mpg I can make it play a tune
I noticed today it really seems RPM-independent. In 4th gear at 2,200RPM is whines (47mph). In 3rd gear at about 3,000RPM (also at 47mph) it whines.
I am secretly hoping it is just a wheel-bearing. If it's the transmission I am guessing it is on the output shaft.

Mike Murphy

I think you have narrowed it down. Whine often comes from gears, whereas wheel bearings or CV joints tend to grind or hum.

Porschetech3

Sounds like the "classic pinion bearing failure"..Part number

99630280800

Requires full trans disassembly. This job is to be done by professionals only, and specifically g96 /xx trans specialist, or the very mechanically inclined and not " faint of heart " DIY'ers...

Argeo

How many miles on the car?
Best of luck.

lowpue

+1....I had these symptoms and it was pinion bearing.

makbloom

75k

makbloom

Sounds like it's going to cost me!

The Producer

Have had this issue myself, and it's not fun - but I don't know if the issue applied to OP's tiptronic trans.

Not saying it's not the problem, but the part number you referenced doesn't even apply to the tip cars.

Porschetech3

Yep, you're right I missed the "tip" in my analysis, so my comment doesn't apply, nor does the part number.

The "Tip" is an A96 ZF trans, not a G96 Getrag..

MY A96 ZF Tip has a little "whine" at speeds, been doing it for 80K miles, just a little ring-n-pinion gear whine (not failing bearing whine)..

neilll

I almost hesitate to say it as there isn’t a ton to go on here but I recall seeing some talk of front diff whine when failing.

makbloom

So no need to worry too much at this time?