Loud Hum. Bad Wheel Bearing? Broken off Abs sensor? Transfercase?

[bigskyeric]

Hi everyone, I've searched this forum for a couple weeks now but haven't found the answer to my 2004's problem. She just turned 201,000 miles last week.

The issue started about 3 weeks ago when the temps dropped down below zero here in northern Minnesota. The sound is coming from the rear and sounds like a bad wheel bearing and it's loud. But it comes and goes. The closest noise I've ever heard to this is on late model pontiac grand ams and oldsmobile aleros when the abs sensor breaks off and grinds against the hub. It's a very loud noise and i believe it's coming from the rear passenger side.

I thought it could possibly be my transmission so i got the truck up to speed and dropped it into neutral. The sound persists and doesn't change at all when doing this so I'm ruling out the transmission unless you know otherwise.

Could it possibly be the transfer case? From my experience with wheel bearings... once they start making noise, they don't stop. The truck has gone 3 days in a row without making the noise. Yet it seems to happen more when it gets really cold out. today it was -20 when it started. But it didn't start right away, it happened after coming to a stop on a hill after 10 miles of driving. And just like the other times it happens... it only last for a little while then goes away again.

Rear Diff?

Broken off Abs sensor? again... once they break off they I'd think the noise wouldn't vanish and reappear.

Any advice will be much appreciated before I start throwing money at it. The ABS pump is going too and that's going to cost me a pretty penny unless if i don't find a used one.


Thanks!

 

[fdbyrne]

If the noise doesn't change when you accelerate, decelerate, or put it in neutral I'd say it's not likely to be the differential.

I've been wrong before though.

Maybe a rear caliper starting to stick?

 

[bigskyeric]

If the noise doesn't change when you accelerate, decelerate, or put it in neutral I'd say it's not likely to be the differential.

I've been wrong before though.

Maybe a rear caliper starting to stick?

I thought of that too, but it doesn't pull or feel likes it's slowing the truck down. It does occur after I've used the brakes though.

I've never heard a stuck caliper making a noise that resembles a wheel bearing. And it gets loud in the cabin of the truck, you can hear it over the radio.