Drivetrain whine like it's going out of style

[clean2g]

I have this whine coming from somewhere in the drivetrain (mid to rear of the car). It has progressively gotten louder since last year. It only whines when I let off the gas, and seems to be loudest when I let off the gas at higher RPM's. I swear it's coming from somewhere mid to rear of the car. I doubt it's the tranny, it was rebuilt by Shep about 40k miles ago. I'm thinking t-case but I'm not sure.

The t-case was leaking a little fluid at one point but that stopped. Fluid level was fine and I topped it off just in case a while back. I had actually taken it to the dealer to see if I qualified for the t-case recall about a year or two ago when I noticed some drips from the t-case on the garage floor, but they said doesn't qualify and wouldn't budge. I don't want the rear end or the t-case to lock up on my while driving.

Has anyone dealt with this? Any simple checks I can do before I have to actually remove and inspect the t-case and/or rear end?

[Speedfreak]

Check/swap out your rear end fluid. It may or may not be your issue, but it's probably never been changed. Hit me up on IM.

[Matt D.]

I'd change the fluid of the transfer case and rear end and see what happens.

[Goat Blower]

If the rear diff fluid doesn't take care of it, it's a worn pinion gear.

[Nartanian]

You might want to check that out pretty fast. I've heard of people having their rear end locking up going highway speeds not to long after neglecting that whine.

[Speedfreak]

BTW, do you have any spots/leaks on your garage floor? Take a quick look under the car at the rear end to see if you can spot any wetness or signs of leaking at any point in the past.

[mlomker]

Originally Posted by Goat Blower

a worn pinion gear.

That was my first thought. Not the cheapest rebuild if yours is anything like the Evos.

[clean2g]

I'm going to replace the fluid in both the rear diff and t-case Saturday morning, hopefully that resolves it.

Mo: no leaks on the floor as far as I can tell near the rear of the car, but haven't looked close underneath for wetness or drips.

[CarPsyco84]

Any luck?

[clean2g]

No, I haven't had time to check anything. I noticed another thing though - the whine seems to only happen during deceleration, while in a gear... which kind of makes me think it might actually be clutch/tranny/t-case.

[clean2g]

I believe I figured out what it is - I went to a mechanic that I trust and he showed me that the driveshaft has play in it, like 3/8 of an inch of play when I rotate it by hand near the rear end. So it is in fact a worn pinion gear and I need to rebuild my rear end or buy one.. fun. Thanks for the help

[Pushit2.0]

Rear end: either the pinion or ring gear, transfer case, center diff lower housing/3rd gear in the tranny.

~John