This new noise is driving me nuts... The truck has about 60,000 miles on it and lately I've noticed a new noise. When cruising down the highway there's a wah-wah-wah sound. When I slow down without touching the brake it sounds like a low growl and can hear it until it gets under 5 miles per hour. I tried shifting into neutral while slowing down and no difference in sound. It does not seem to change in pitch or in volume while turning.

I had the front wheels off the ground, they turned without making a noise and there does not seem to be any play (up/down or in/out) in them.

I changed the front and rear diff this weekend. The front was really clean, the rear - well the fluid was a little darker than the front, the fill plug had a pretty good paste of metal on it and there was a little bit of foam. I think, from what I've read here, that this is fairly normal. I have an old Chevy that has a howl in the rear end and this noise really doesn't sound the same.

I have a fairly new set of E load rated Goodyear Silent Armor tires (can't say I'd recommend them, but that's another thread) and there is minimal cupping on two (rotated this weekend). The noise now seems slightly louder in the rear (but I'm not sure I can blame it on the tires if I can hear it at 5 mph).

I realize it is difficult to diagnose this way, but any ideas on what I can do to locate the cause of this noise?

Any thoughts on this would be greatly appreciated.

Brad

 

rear drive shaft u-joints??

 

Carrier bearing?? U-joints??

 

Thanks for the replies.

I'm not feeling any vibration at all - wouldn't I feel something if the U joints were going?

I'll have to dig into the carrier bearing - that just might be it. How hard is it to replace?

 

Thought I'd post a little update. It turned out to be a rear U-Joint - I wasn't able to find it until it got pretty loud (almost as loud as running over a rumble strip) while driving 70 and just an ever so slight vibration that I swear wasn't there even last week.

Thanks again for all the input!