Hi all, I was hoping for some help troubleshooting some noises coming from my 2008 Avalanche 5.3L 4x4 with 160K miles. When the truck is in motion, starting at about 20 mph, I begin hearing a low whine/hum that gets higher pitched as speed (not RPMs) increases, although I can?t say it gets too much louder with speed. The sound is similar to bad tire/pavement noise, but pretty sure it?s not that. No grinding noises (yet), just whining, and does not get so high-pitched that I would can it squealing. It seems to have gotten more noticeable since it started a few weeks ago.
I want to say it?s coming from the front, but its so hard to say for sure the way sounds travel in the car. Its most noticeable when accelerating and under load, and does tail off when taking the foot off the gas (or putting it into neutral), but doesn?t go away immediately or completely. The ?interesting? thing is that when I put it into 4WDH, the sound seems to get a little louder and consistent, and no longer tails off when decelerating. The sound also doesn?t change when turning the wheel.
I had a transmission rebuild last August, and there is only 15,000 miles on the truck since then. The tranny fluid looks fine, although it may be a little high. Both front wheel bearings were replaced 2-3 yrs ago, and the rear differential bearings were all replaced 3 yrs ago. I have also been experiencing an occasional clunk when changing drive/reverse and sometimes during low speed gear changes which I was attributing to the slip yoke, but maybe its related.
The fact that the sound is a little worse and more consistent when 4WD is engaged makes me think it?s in the front end, but I don?t think its wheel bearings again since they were recently replaced and turning the car doesn?t change the noise. I would also be surprised if it?s the tranny since it was recent rebuilt. Maybe front CV joints, transfer case, front differential?
Thanks in advance!
I want to say it?s coming from the front, but its so hard to say for sure the way sounds travel in the car. Its most noticeable when accelerating and under load, and does tail off when taking the foot off the gas (or putting it into neutral), but doesn?t go away immediately or completely. The ?interesting? thing is that when I put it into 4WDH, the sound seems to get a little louder and consistent, and no longer tails off when decelerating. The sound also doesn?t change when turning the wheel.
I had a transmission rebuild last August, and there is only 15,000 miles on the truck since then. The tranny fluid looks fine, although it may be a little high. Both front wheel bearings were replaced 2-3 yrs ago, and the rear differential bearings were all replaced 3 yrs ago. I have also been experiencing an occasional clunk when changing drive/reverse and sometimes during low speed gear changes which I was attributing to the slip yoke, but maybe its related.
The fact that the sound is a little worse and more consistent when 4WD is engaged makes me think it?s in the front end, but I don?t think its wheel bearings again since they were recently replaced and turning the car doesn?t change the noise. I would also be surprised if it?s the tranny since it was recent rebuilt. Maybe front CV joints, transfer case, front differential?
Thanks in advance!