twittyaustin

I have a 2004 stx 4x4. I noticed that my rear pinion seal was leaking. So I fixed that. A few days later, I noticed a slight whine/hum that sounds like what tires with an aggressive tread pattern puts off (my tires are stock) coming from what sounds to me like the right rear of the truck. The hum is noticeable from about 17 mph on up, and very noticeable when coasting from about 40 back down to 17. I don’t really know that I am explaining it right, but the whine never changes as the transmission shifts or follows along with the rpm, it steadily increases as the mph increases and follows the same pattern on decrease.

Anyone got a suggestion as to what I may be dealing with here?
Thanks,

dcrabby

universal joint
axle bearing
differential gear clash

dcrabby

how about correct gear lube, correct additives and correct amount
did you replace lube lost by the leak

twittyaustin

I was hearing the whine before i changed the seal, i was hopeing it would fix it. but it didnt. it was synthetic with the special stuff for the ls rear end

SCGC01F1

Mine did exactly that for a while, thought it was front wheel bearing. Turns out it was the pinion bearing. Jack up the rear end and put it in drive and listen. If you loosened the pinion nut to change the seal you also may not have the pinion nut tightened properly...

twittyaustin

did you have to change both bearings?

SCGC01F1

Yes. Wasn't too bad but mine is limited slip so had to remove the carrier entirely and tap the pinion out. But you have to take the carrier out to really hear if the inner pinion bearing is bad in my experience. This was the one time I had to do this a while ago. Also, I got a ,aster install kit from east coast gear supply. If you have to take the carrier out you might as well replace everything. The bearings are pressed on as well.

Jds

I just started to notice my 06 fx4 making the same whine noise.

SCGC01F1

Hard to tell from inside the truck too. Best advice I can give is, like I said earlier, jack up the rear of the truck and have a friend put it in drive and slowly let off the brake. Only sure fire way to tell if you have something awry in the pumpkin in my experience.

twittyaustin

anything i should look for before digging into the axle?