I've had a growling noise coming from the rear end of the truck for some time now. It was pretty mild at first but in the last couple weeks has gotten loud. I can hear it as slow as ~20 mph and it gets louder with speed. If I let off the gas or put it in neutral while on the highway, it gets much quieter but it doesn't go away completely. I just took a 6 mile trip on the highway, up to 60 mph, and got under the truck to feel the diff. It was quite warm, especially in the front. My friend thinks perhaps my pinion bearing has gone south. We were inside for about a half hour and then came back out and made the same 6 mile trip back here and it felt even hotter.

Recommendations?

unbolt the drive shaft and put the rear on jack stands and give the pinion a spin and see how it feels, if you dont like the noise you get your half way to pulling the rear end already...

Done. Surprisingly, I didn't really hear anything from the pinion at all. I did hear some noise coming from the PS wheel. It feels rock solid when I push and pull on it but it does make some noise when I spin it. It is not constant but it almost sounds like there's one or two metal shavings that are grinding in a rotating assembly.

Could this be caused by my brakes? Or is the wheel bearing likely the cause of this and the vibration/growling I'm getting on the road? Or are these two separate issues? How do you tell if you have ring and pinion issues?

This is the first driveline problem I've ever had except for a Jeep I used to own that popped its diff two or three times. It was under warranty so I just took it to the dealer every time.

I drained the fluid to see if chunks of metal would come out but it looked pretty good. There was a coating of gray slime on the drain plug but no discernible metal shavings anywhere. It seems as though there is a good bit of play in the diff but I really don't know how much is normal. I can turn the input flange 1/16 to 1/8 of a turn without engaging it and it spinning the wheels.

Im going to vote wheel bearing on this one, the pinion wont feel 100% smooth even with the axles out, the rear bearings make the noise you describe as well, its easier to hear at slow speeds around 20-25, replaced driver side on mine last year at about 115k

There is more noise from both wheel bearings than there is from the pinion but they're not loud, I can just hear the wheel spinning on them. Wouldn't they make noise all the time? Mine really only growls under power. When I'm coasting, the noise is almost completely gone.



Mine is much louder at higher speeds. The noise/vibration level is proportional to the speed that I'm travelling.

On another note, I did have some resistance in the U-joint right there in front of the pinion so I know I've got to replace that but I suspect that's not the noise that I'm hearing.

Yep, definitely check the cheaper/easier stuff like u-joints first.

That pinion flange on the diff should have no play in it at all. If it does, you've got problems there that need to be addressed.

when i checked my wheel bearing i had to have it in gear and the tires spinning on the lift to hear them growling, couldnt hear anything spinning by hand...

The axle bearings in the rear end will growl much louder (when bad) when you load the truck in its direction. To check, drive straight at about 40 or higher, turn fairly sharply in one direction and see if the noise increases by quite a lot. Then do the turn the other way to see if the other side is the problem. If there is no significant difference in the noise level it is not axle bearings. Bad pinion bearings will result may resullt in sloppy pinion condition but not unless really bad. Drain the oil and see if you have metallic stuff in the oil. If you do then every bearing in the assembly is going to have to be replaced, including the axle bearings as I believe they are not sealed units, but oiled by the rear end oil. Another spot to look is the carrier bearing. The 2 piece drive shaft is cradled in the middle at the u-joint by a rubber suspended bearing. These things are right out in the slop when you are driving and make one heck of a growl when dried out. Most factory carrier bearings are not provided with a grease joint so they eventually dry out the factory lube and go to pot.

My bet would be the carrier bearing..

The axle bearings are sealed.

The silver/grey slime you found on the drain plug is normal.

If you do find you have bad pinion or carrier bearings, you may want to price out buying a used one vs. having it repaired. car-part.com has some good deals sometimes.

Wow. All good replies.

I will put up the back end and spin the wheels with the driveline tonight. I actually meant to do that last night and somehow missed it. I will also do the double lane change test on the way home to see if there's any noticable difference in noise level between the L and R. That should be an eye opener for my daughter. <img src="/forums/images/graemlins/lol.gif" alt="" />

I'm going to replace the U-joint that I know is bad tonight, do these wheel bearing tests, and go from there.

Thanks everyone for the replies.