[m1e9r5c6]

Hi everyone. Yesterday I went for a short trip (200 km). All seemed fine on the way but when it came time to come home I had issues.

Started the truck and warmed it up (-20C outside). Backed up and pulled out of the driveway. Stopped at the end of a gravel access road, all was normal. Then pulled onto the highway, accelerated briefly, then decelerated to make a turn. That's when all of a sudden there was a loud howling noise.

I've never heard this before. Playing around with it I've notice the following:

1. Sound seems to not be there when accelerating or cruising at any speed,
2. Howling is very loud when decelerating,
3. When decelerating from highway speed sound gets louder while approaching 30mph then lessens down to 0,
4. No sound when coasting in neutral.

Any ideas? FYI, I recently had a new reman transfer case installed. They also installed a new rear pinion seal at the same time. Could any of this be the culprit?

 

[bth232000]

Possibly a bad throwout bearing... They'll constantly have a load hum that gets louder when you let off the throttle. Just an idea

 

[m1e9r5c6]

Thanks. I thought about that but, would I have noise at idle too then?

Anyone else have a different idea?

 

[rgaskell]

The new pinion seal is suspect to me. Pretty much improper preload on the bearing now.

 

[m1e9r5c6]

Yeah, that was my concern doing the seal myself. I didn't have the tools to measure rolling torque before and after so got the shop to do it. I suspect they jsut tightened er down and called it good.

Thankfully I only have 500 miles on since, otherwise I imagine this could cause more problems?

 

[mikjas2]

My plow truck did the same thing although its an older chevy. It was the yoke on the rear end loosened up and since you say the pinion seal was just done Id say pretty good chance