Thumping and hopping in 4 WD

[waynep]

Hello All:

Had a transfer case run dry, and now when I put it in 4 wd high from dash button, the truck kinda thumps and hops a bit when moving slowly down the road, relatively dry road. Never did it befor on fdry road.
Does this sound like a bad transfer case? In 2wd runs fine.

1997, 2500 Diesel Surburban.

[DmaxMaverick]

Verify your front/rear gear ratios are the same, including tire size (mark, roll, measure). Wishful thinking. Be optimistic.

Check U-Joints (most common cause). Check splines for excessive play.

How did you "run it dry"? How long/far? Under what load condition? The lower end of the TC is bath-lubed. The upper is pumped. Most often, dry will pooch the TC very quick.

[waynep]

Hello DMax:

4WD worked fine for years and with no changes except transfer case slow leak ran it dry, and then hopping started. Checked all universals, CVs and wheel bearings. All look and feel OK.
I am not sure how long it ran dry, but leak was very slow, and I top it off and check it fairly often.

So I think it is TC but runs fine in 2 wd, but have not checked 4 wd on snow.

Thanksd for the input.

[DmaxMaverick]

It's hard to say. Pull the plug and check for metal on the magnet and in the drain fluid. It should have been serviced with Dexron III ATF (bad ju-ju if it wasn't).

[waynep]

Hello DMax:

No metal or other crud. Yes, used Dexron III for sure.

Gonna look at it closer this weekend and also see where it might be leaking.

Regards,
Wayne