Rear diff wining

[maddzz1]

When I'm driving on the highway and excellerating there is a loud wining noise. When I let off the gas the noise stops. I just bought this xj a few weeks ago and noticed that the rear diff seems to have a leak from the gasket. Could this noise be from the fluid being low or is more likely something else? Maybe the tranny not shifting into 4th gear?

[Pete M]

If you don't know the date of the last oil change, that sounds like a good place to start. :thumbsup:

[maddzz1]

If you don't know the date of the last oil change, that sounds like a good place to start. :thumbsup:

 

This is for an 8.25. Do I need to add anything to the oil, like for a limited slip on an MJ? If so, what is it called and how much?

[Pete M]

Do you have a limited slip in it? If not, then it should just be straight gear oil. :thumbsup:

[maddzz1]

Do you have a limited slip in it? If not, then it should just be straight gear oil. :thumbsup:

 

I'm not sure? how can I tell? Any pics of what it will look like with the limited slip and without? Ive never taken a diff cover off before.

[jtdesigns]

You have a BA-10?

[maddzz1]

You have a BA-10?

 

No, its an automatic. AW4

[jtdesigns]

My truck whines when its moving any at all, but its the puke 5spd.. I'd just drive it till it broke, then swap.

[maddzz1]

My truck whines when its moving any at all, but its the puke 5spd.. I'd just drive it till it broke, then swap.

 

The wife drives it with the kids. So thats not an option. Thats what i do with my truck. :wrench:

[jtdesigns]

Pull the rear cover and get all the old oil out, clean the surfaces of the cover and where it mates up to the housing, get some RTV and reinstall the cover, then refill at the plug until oil starts to drip out where your filling it.

[DirtyComanche]

And you can always use gear oil with the friction modifier for a L/S in a regular diff... A lot of the gear oil has it in it.

[comancheman]

my d35 did the same thing awhile back. step on the gas and it starts howling, let off and noise goes away. i changed the fluid and it got better but not perfect. A few weeks later i changed it again and did half 80-90 gear oil and half lucas oil stabilizer. It seemed to get better overtime and now i don't hear the howling at all. My rear end has about 190k on it though. I don't know how many miles your 8.25 has on it but it doesnt seem like it should be having issues unless it was abused.

[james750]

pinion bearing?

[Sir Sam]

IIRC the LSd in the 8.25 is a clutch type and not a viscous LSD....IE no need for the friction modifier.......

[bigd44889]

my camaro did same thing as stated above pinion

grab d/s right in front of rear u/j and push up and down if it moves

pinion berings are shot

[maddzz1]

my camaro did same thing as stated above pinion

grab d/s right in front of rear u/j and push up and down if it moves

pinion berings are shot

 

I tried this with the rear ds and no movement at all.

 

Although unrelated to the above problem the front driveshaft had no up and down movement it did have some movement if I twisted it.

[TNT]

That sound like a backlash issue, but pinion bearings are a possibility too.

 

If you put the truck up on jackstands in 2wd and the front tires blocked you can probably pin point it. Use a mechanics stethescope or short piece of broom handle held tight to your ear you can pin point the noise by listening to the different locations on the axle while somebody elsedrives it tryng to duplicate the sound. This will let you check the pinion bearings easily.

 

If you pull the cover you can chech backlash then also.