2008 Yukon Rear End Howl

[PReal]

My 2008 Yukon has a strange noise coming from the rear of the truck. When going around 50+ mph I get a howl coming from the back of the truck. It is only noticeable when I am accelerating and it sounds different on different roads. I've changed the rear diff fluid, but I'm tempted to do it again becuase I concerned by scotchbrite pad may have left some residue in the diff.

Any thoughts?

I've got a vacuum brake bleader and I've thought about adding a hose to the end and just sucking out most of the diff fluid and replacing it.

 

[Barkleymut]

next time don't used a scotchbrite pad. Did you use the correct viscosity when refilling? When did the noise start? Before or after changing fluid?

 

[Sawdusted]

Could be your rear wheel bearings?

 

[Trav]

If it was quiet before you changed it, it could be low on fluid. Did you do this on ramps with only the rear end raised?

 

[Mud]

I assume the noise was before the gear lube change?

Is this a limited slip unit? If so, did you use GM additive? I doubt small amount of scotchbrite pad will do anything harmful.

What was the condition of the fluid that you drained? All axle fluid will show some trace metal, but if it was very glittery you may have a bearing or pinion gearset that is damaged.

Cheapest first step is to change the lube, but you did that, just wanted to ensure you used the right fluid.

 

[PReal]

The noise was there before and after the fluid change. I have rechecked the fluid and it was full.

I used valvoline synthetic 75w-90 with the included limited slip additive. It is the suggested weight for the diff.

I would think something like wheel bearings would be constant.

What are the thoughts on drainging most of the fluid with the vacuum and replacing.

 

[ARCOgraphite]

Could be a tire too. I would leave the fluid alone. IS this unit spec for 75w?
A cv would be more of a rumble or clicking.

 

[PReal]

I sounds like a driveline noise. I've read some online that suggested pinion bearing or u-joint. I have a couple quarts of diff fluid at the house and I may just try to vacuum drain some.

 

[SwampSurvivor]

What were you using a scotchbrite pad for?

 

[PReal]

I used a scotcbrite pad on a die grinder to remove the stubborn RTV from the housing...

I think I went a little overboard for getting the old rtv off...

 

[Trav]

Originally Posted By: PReal
I sounds like a driveline noise. I've read some online that suggested pinion bearing or u-joint. I have a couple quarts of diff fluid at the house and I may just try to vacuum drain some.


It could be a rear pinion bearing but you need to get this checked out professionally, no way to get an accurate diagnosis this way.
I seriously doubt changing the fluid is going to do much of anything except cost money.

 

[GSCJR]

This ^^^

 

[Cardenio327]

Originally Posted By: ARCOgraphite
Could be a tire too.


^Simple things first^ Maybe try a tire rotation first, you never know, the noise might move to the front.

Wheel bearing noises usually change in pitch as you go around curves, it sounds like your noise changes on acceleration, which could be a tire.

 

[WiskyBadger]

My pickup did the same and it was the pinion bearing.

 

[PReal]

Originally Posted By: ChevyBadger
My pickup did the same and it was the pinion bearing.


What did it take/cost to fix it?

 

[SwampSurvivor]

Originally Posted By: PReal
Originally Posted By: ChevyBadger
My pickup did the same and it was the pinion bearing.


What did it take/cost to fix it?


I had a bad pinion bearing on my Cherokee. The labor alone was going to be $250 to $300. It requires the entire differential to be disassembled and the gears have to be reset once its replaced.

I decided a junkyard axle was a good idea at that point.

 

[PReal]

I'd rather pay 400-500 on a pinion bearing replacement then buy a junkyard axle. If this was my 97 pathfinder I'd go the junkyard route but this is still a $25k car...

 

[threeputtpar]

Had the same issue on a 2005 Mountaineer. Bought the car with 9500 miles and the noise was there immediately. Only between 54 and 60 mph and only while holding speed or accelerating.

I changed the fluid twice with 75W-140 to try to quell the noise with no success. Traded it in at 110k miles with the same noise and never had to replace anything.

 

[A_Harman]

Because it only makes the noise under acceleration, it sounds like the pinion depth in the ring and pinion is out.
Did the rear end always make the noise?

 

[ARCOgraphite]

Just a truck rear end, nothing super special. Too bad its a touchy job requiring big tools OTW you could shade tree it. Got any friend in the Commercial/HD truck repair business you can bribe?