StratfordShark

All of a sudden I can hear a low pitched whirring noise, which goes up and down with revs.

Searched here and thought uh-oh, torque tube bearings, but shifting to neutral doesn't make much difference to the noise. Seems to disappear or almost disappears when you select reverse.

It's like a growling which seems to come from behind centre of dash, but of course may be being transmitted from elsewhere. Seems to be an acoustic thing or vibration as you can't hear it properly when you open the hood.

Any ideas please?

TIA

the flyin' scotsman

Helicopter?

when did you last maintain the tbelt and accessory belts?

StratfordShark

No low flying 'copters here, but the tbelt hasn't been changed for 6 years (about 20,000 miles) though I re-tensioned it recently after getting a belt warning. No warnings now but I know t-belt change urgent.

Not sure when any of the accessory belts were last changed. I was thinking it could be a belt thing, with the noise finally emerging in cabin the way I hear it. Would a worn accessory belt be consistent with the noise reducing in reverse though?

Jim bailey - 928 International

The driveshaft in the torque tube on an automatic spins ALL THE TIME with the automatic even in neutral it is bolted to the flywheel .

StratfordShark

Hi Jim,

This will sound a stupid question but could you explain the thing about rolling in PARK and best way to check?

Thanks

Jim bailey - 928 International

Sorry about that I cross posted .....not your pronlem I will edit it !!!!

Charley B

My guess is water pump or torque tube. I'm ignoring the "sounds different in reverse" since I can't make sense of that.

the flyin' scotsman

I fly RC birds and they make one hell of a 'whirring' noise with blades spinning @ 16k............but we digress.

So, was it making a noise before the re-tension, if not perhaps there's the issue there.............re-check?

If you haven't changed them and have no record when last done they're cheep. There was a post not long ago with an alt. belt breaking taking out the air pump belt also. Can imagine a much more catastrophic issue and all for a $10 belt and a little TLC.

ROG100

Rear Carrier Bearings - they are only $30 each for the 2 - its the 10 to 15 hours labor thats the killer.
Has it being getting louder as you pile the miles on?

928Quest

Is not a sudden need to re-tension after 20K miles sometimes an indication of a failing part in the T-belt path? I know after the 1K retention my T-belt changes very little.

3000teeth

Is it behind you -- maybe need to add fluid to the diff (just circumspect, as I've not done this myself, but been told I should).

Either that, or you're driving a 911. They whirr, don't they?

StratfordShark

Thanks for all the suggestions guys.

Have only been aware of the noise on last few outings, so can't tell if sound is getting worse.

ROG100

if it is the rear carrier bearings it will slowly get louder and louder until you can bear it no more.
Only one of the bearings (front) seems to fail. However you do change both of them WYAAI.
They do not seem to fail just get louder.
The noise is transmitted forward through the TT.
Seems like its coming from the center console in front of the gear selector.
I hope it is something simpler for your sake. 8<(