03 Yukon Oscillating Noise

03GMCYukon · August 20, 2016

2003 GMC Yukon SLT, 2WD, Auto, 135K miles

My Yukon has an oscillating noise coming from the driveline. It's my son's vehicle in college so trying to determine if there is a safety issue and if I should pay the $100 diagnostic fee at the dealer to figure it out for sure.

Noise characteristics are:

- noise varies with speed of vehicle. Noise isn't grinding or tinny. Kind of sounds like rrrrr, rrrrrr, rrrrrr with each noise occurring at 1X per wheel rotating.

- slight acceleration makes the noise go away but braking does not affect the noise

- 10 to 25 mph, coasting, is when noise if most present

- turning left or right will make the noise go away

- putting trans in neutral has no effect

I bought the vehicle with 3 miles on odo so know the complete history. Arizona vehicle. Brakes have not been changed (6mm remaining) as it's flat in Arizona and I do a lot of freeway traveling. Tires are almost new and were just checked with nothing notable. Rear diff fluid changed at 98K at Chevy dealership. Just had front end aligned when changed the front upper A arms (ball joint boot was split open)

Here are my two cents on possibilities:

Engine - no, as noise varies with vehicle speed not engine speed

Tranny - unlikely given that putting trans in neutral doesn't have an effect on the noise

Axle joints - not sure

Diff - not sure

Rear bearings - not sure

Front/Rear tires - seems unlikely given they were just checked and relatively new

Front/Rear brakes/rotors - not sure

Front wheel bearings - not sure but turning or slight accel causing noise to go away seems odd

Any experience to help point me in the right direction? Thanks.

00_NUTT · August 21, 2016

I'd look at the front bearings. Now the hub bearing and all is a sealed unit but it sounds like it's starting to go on you. Jack it up and see if you feel any slack(push in and out on the tire), roughness or hear noise on either side. If so the part is around a $100 bucks and should take about an hour to change taking your time. Mine kinda of did the same but was really noticeable when getting on and off the interstate.

03GMCYukon · October 23, 2016

Took it to the dealership and they found LR axle slightly bent (hit a curb, side impact ~3 yrs ago hard enough to break tire bead and damage wheel so not really surprised axle slightly bent).

LR axle and outside bearing replaced ($850 total incl labor) but no change of the oscillating noise. Tech commented no metal found in diff and ring gear looked great for 135K miles.

Technician (been with dealership for ~15 years and is the lead tech) wants to take differential apart and check inner axle bearings, pinion bearings, etc. I'm guessing another ~$800.

I feel like I'm chasing a problem though. I have high trust with the Tech but getting concerned with the "take things apart and see" approach. However, it may be the only option.

Any ideas or thoughts on this tough one?