whining noise when coasting

[Dr Vic]

I have a 1990 talon tsi awd that is whines when Im coasting. This does not happen when I only go up to 45 mph. It usually happens after I take my car to the highway driving 70 mph. It does not happen when Im going at 70 mph it usually starts when I decelerate. The noise remains even if I go on neutral. Revving the engine does not make it worse.

The car has 0 mods done. well taken care of by its previous owner. Never raced. Since I did the drivers side ball joint I also checked the bearing on the drivers side CV and it was fine. Is there any chance my drive shaft carrier bearing are worn? I visually inspected them and they look ok.

 

[AK Thunder]

Sounds like a wheel bearing going out. Most that I've replaced have been when the wheel is under an acceleration load but I've had a few only make noise under deceleration.

Another suspect I'd look at is one of your drive-line U-joints.
A quick test on the drive line if you cant get underneath the car is while stopped shift from reverse to drive and back to reverse and listen for a clunking from underneath the car (around middle-to back) if its an auto.
Same thing with a manual you'll just have to slip the clutch.

 

[Dr Vic]

Ive changed the front drivers side wheel bearing already and Im sure Ive checked front passenger. Ill check the rear bearings tomorrow. So this does not sound like the rear diff, timing components or drive shaft bearings then?

 

[white92talontsi]

Sounds like the pinion bearing in the rear diff or the t-case.

 

[AK Thunder]

Check your rear diff fluid(this should be regular maintenance anyway). If it smells burnt, drain and fill with 75w-140. Also wouldn't hurt to do your t-case while you're at it. (also 75w-140)

I personally have not had a carrier bearing crap out on me. Check the rubber on it to see if its dry rotted/cracked/ or completely broken off, although in that case I'd think your hear banging from the drive-line smacking around the support.

If you have access to a vehicle lift you can use an automotive stethoscope and with the car off the ground and wheels moving listen around for any unusual growling/grinding/ or whining noises.

Never heard of timing components doing this either, but pull the cover and check the belt and see if its worn or damaged!

Sounds like the pinion bearing in the rear diff or the t-case.

Lets hope this is not the case!

 

[Dr Vic]

both the tcase and rear diff are full of fluid. Ill check if they smell burnt. How can I check the pinion bearing on the tcase or the rear diff? Is it just by taking the driveshaft out and checking them for movement?

 

[AK Thunder]

Pull the drive line and with a dial indicator check the in and out movement on the t-case pinion flange. I'm not sure what the spec if but a quick look in a repair manual should have the spec.

If I'm not mistaken the rear diff is a slip joint so you'll just pull the whole yolk out if you pull on it(this won't damage it, just make sure if you do this to make sure you place the yolk on a clean rag and make sure its spotless before you reinstall.)
You can check the backlash on the ring-gear and pinion flange on the rear diff, but its a P.I.T.A to do it in the car.

 

[Dr Vic]

I've jacked the rear end of the car and I found that the carrier bearings appear to have separated from the rubber. I don't hear any thumping or noise during heavy loads. can a bad carrier bearing cause a whining noise only during deceleration from 70?

Just for review the noise is consistent when coasting and does not get worse if the car is put in neutral and revved.