MikeG76

My 2005 GT 5-speed with 186K miles has developed a whirring noise that happens from 20MPH or higher. Acceleration, braking, turning have no effect on the noise. No notable vibration either. Any idea which part this might be? The center carrier bearing in the driveshaft? Or something else? Thanks,

Dino Dino Bambino

Can you localize the whining sound to any part of the vehicle?
There are a number of possible causes and a video might help.
Is it worse in any particular gear or is it the same in all gears, including neutral?

MikeG76

It is the same in all gears and neutral. Pushing in the clutch makes no difference. It is hard to localize but seems to be coming from behind me.

Derf00

Diff fluid might be totally wasted or the diff is low on fluid. Check the level and condition through he fill hole.

MikeG76

Should it be full to just under the fill hole?

Dino Dino Bambino

The source could be the rear diff, but a whine from there is typically low pitched at low road speed and becomes higher pitched as you increase speed. If it's low on fluid, there could be a leak from either the pinion seal or the axleshaft seals. Topping it up may alleviate the problem.
Since it's coming from behind you, a worn driveshaft center bearing is likely. That usually produces a low pitched rumbling sound, plus vibes that increase in severity at higher road speeds. An easy way to check is to put the car up on a lift and see if there's slop in the center bearing.

MikeG76

Dino, sorry I wasn't clear that the pitch does change with road speed. It just doesn't matter what gear it is in at that speed. I also don't have any vibration issues. I'll check the fluid level probably Monday as we're going out of town this weekend (in another vehicle).

Siber Express

Carrier bearing would be speed related. Does it do it when you are coasting or not on the throttle like maybe a Fuel pump going out? You also have two fuel pumps the second one is a transfer pump that might actually kick on around 20 when the fuel level drops while accelerating.

MikeG76

It makes the noise when accelerating, coasting, light throttle and during braking. It is harder to hear when on the throttle due to my loud exhaust but the noise is there.

MikeG76

How much play is there usually in the center bearing? I have not checked the diff fluid yet but can move the center bearing some. But I dont know how much play is normal.