Low pitch whine in 98 4x4

[kdcarter]

In my 98 b3000 4x4 I have developed a very low pitched whine (not quiet, necessarily, just low pitched) that is most evident when gliding into a stop. It may be there when accelerating or driving, but engine noise would cover it up if it is there then. In deceleration it is would be missed by someone who had not driven the truck before the low whine developed, as it could be mistaken for normal engine noise. My guess is that it is coming from the front end, but it's hard to tell. I do have AVM manual hubs installed. Any places to look first?

 

[triumphrider-1]

How old are the bearings?

 

[Andy D]

Check the front diff for lube level, also the trans, the transfer case and the rear diff. Good luck

 

[Haywire6000]

My 1993 does the same thing. I know mines the transfer case. I keep the fluids clean and haven't had a problem. I live in maine and spend most of the winder in 4x4.

 

[adsm08]

Sounds like wheel bearings to me.

 

[Andy D]

Heh heh, the Rat is in 4 wheel high with the hubs unlocked. My electric motor has been replaced by some white paint and a pair of dedicated vise grips. It's a PITA to shift and it takes some fiddling to get it shifted into 4 wheel high, so I leave it there and runaround on open hubs. Even if I fixed the electric shift. I would still have to get out and lock the hubs. Jeep SJs did it right with a limited slip transfer case. Manual 208s were a base option. After 5 Grand Wagoneers , I guess I'm spoiled. Getting out to engage 4wd, egad!

 

[kdcarter]

Thanks for the suggestions. The bearings are old enough to be replaced, but I will also check to make sure the transfer case is not engaged. The lights on the dash indicating 4x4 is on are not illuminated.