ok ive been serching all forums for 3 hours now & no answers. only when i give my jeep gas a whistling type noise comes from rear. the noise is like if you try to whistle but just blow out mostly air. if i put in park or neutrel and rev theres no whistle. only when in gear and when hitting gas. my u joints seem tight. but my rearseems to b leaking fluid out the end seals a little. what are the chances its the bearings and not the diff.. gears being that noise only happens when hitting gas.. oh and all fluids are good. please anyone............

 

How many miles on her? Tires and Ujoints be a good place to start. Then I'd remove the rear end case plate and check for exessive play at the diff gears / bearings.

 

Are you getting any vibration or just noise?

 

What kinda jeep ? and rear end is it?

 

Most people describe rear axle noises as a howl, moan or whine, strange that you say it sounds like a whistle. I have seen before where an exhaust system has a hole in it (mainly on mufflers) where it can create a whistle type noise under load and higher RPM.

 

^^ this is what I was thinking as well. Does it do it in reverse? Put it up on jack stands (good secure ones) and block the front end. Have a friend slowly give it some gas in gear in see if you can isolate where it is coming from. Assuming it is part-time 4wd.

Disclaimer: the above procedure should be done with extreme caution and is no way intended to be done without professional supervision and properly securing the vehicle from being able to move in case of jack stand failure. Anyone trying the above procedure assumes any and all risk for doing so!

 

Year
1996
Model
Grand Cherokee
Engine
4.0 6cyl
Transmission
4spd auto-o/d
Transfer Case
stock
Front Axle
stock
Rear Axle
stock
Lift Specifications
stock
Misc Accessories
dynomax turbo thrust exhaust

 

I remember reading somewhere in the FSM that if you hear that kind of sound when coasting its your front differantial, but if it makes the sound when given gas then it is your rear. I think the FSM said something like low fluid or wrong fluid. I know you said the fluid was good, but you also said it was leaking. I would try with a fluid change and inspection.