Rumbling Noise/Vibe after LS DIfferential Oil Change

[hydrogin]

I hope the more experienced folks here can help me with a problem that just came up.

 

Yesterday, I took my 94 XE 4x4 (manual transmission) into the shop for routine maintenance & fluids changes. Included was a change of the F and R differential's gear oil.

 

Driving home from the shop, I noticed some low frequency rumbling noises. I thought it was road noise. Today, the rumbling got much louder and I could feel some vibration coming through the floor and maybe through the steering wheel. I noticed it happens during turns while driving forward and in reverse. The thought occured to me this might be related to the LSD oil change!

 

Can anyone think of some reasons why this might be happening?

 

This shop is one of the oldest & most reputable in town ... I hope they remembered to fill the diffs after draining! I believe the manual calls for 80W-90 LSD gear oil. I'll definitely be taking my Pathy back to the shop on Monday (avoiding as many turns as possible). Thanks for any ideas.

[Towncivilian]

What fluid was used? Do you hear chattering when you drive a figure eight?

Edited January 20, 2013 by Towncivilian

[hydrogin]

Chattering might be a good word to describe it. The sound seems periodic, as if my tires were shaped like a hexagon instead of being round. Doesn't matter whether I turn left or right. The sound is most noticable when I'm turning around a corner slowly. On fast curves, the sound is less noticable ... might be masked by road noise.

 

I don't know what fluid was used by the shop. They did tell me the Pathy doesn't use the "expensive" LSD gear oils some newer SUV's need. The factory manual says to use API GL-5 80W-90.

 

Could an incorrect LSD gear oil cause this noise/chattering?

[adamzan]

If you have an LSD rear diff, you do need the special fluid. Or there is an additive in a small bottle that you can add to regular gear oil. It isn't overly expensive either.

[hagge]

I had the same problem when i got my Terrano a few moths ago.

I changed the oil to spec., and the chattering dissapeared, but it took a few days to compleetly go away.

I think the new fluid has to penetrate properly in between the "friction plates" (do not know the english word) in the LSD diff.

[MY1PATH]

It does not have to be "fancy" or "special" or "expensive" LSD oil but it does need to say LSD somewhere on the bottle. Since they sold you short I'd just put LSD additive in there, it sticks to the plates and keeps them from chattering when the LSD slips (cornering the tighter the turn the more it slips).

[hydrogin]

Thanks for the feedback everyone. I'll post when I get this resolved with my mechanic.

[Towncivilian]

If your mechanic noticed the bright radioactive orange "LSD" sticker on your rear diff and didn't put LS oil or additive in it, he is an incompetent moron. Find a new mechanic.

[hydrogin]

Went back to the shop today and brought a copy of the factory manual's fluids specs. Turns out the mechanic used the correct LSD gear oil. He suspected adding an LSD additive might help. He was right. I tested by driving tight circles in a parking lot, left & right, forward & reverse. No more chatter!

 

Thanks again for everyone's comments.