Thinking about adding to the fleet but want opinions.

[Mudsport96]

So found a local Denali Yukon xl. I have walked around it and glanced under and seems to be 98% rust free. But ad say has some diff noise. Ill post the ad and you guys can read for yourselves, and the AWD guys let me know what you think the noise could be. I know the awd diffs are known for issues, but what are the odds 3 were bad?

 

[B-train]

Yes and no.....

Yes -- these differentials were known for bearing noise. I know A guy who had the same year and style truck. He wanted the front dif rebuilt because of the all-to-common growl noise they make (trucl had about 100k at the time). Took it to a very well respected shop that does top notch work - everything new, assembled to spec, etc. Guess what? After some run in time all the brand new GM parts started sounding the same again. He gave it to his grandson in TX and as far as I know they ran the wheels off it on the rebuild.

No -- because I'd want to see what the reason for replacement really was. (Was it just some noise, or was a real failure) Even with the known noise issues, as long as the fluid was changed on a consistent schedule, they seem to hold up.

 

[Teamiez]

Maybe it wasn’t the right gear ratio with the replacement? Or if they were used units that were bad?

 

[S33k3r]

The wrong gear ratio on an AWD vehicle will cause bucking. I will not admit to how I know.

Most likely they have the G80 locker, and have not used Diff oil with the special friction modifier you are supposed to use with it. I do not know how much damage, or over how short a period of time damage will occur, but that may be your issue.

Other issues that this could be:
A bad U-Joint somewhere
A bad axle shaft
A bad transfer case, but I'm thinking the noise wouldn't be coming from the rear.
Same for a bad front differential
The only other thing I can think it would be would be suspension components

But I can only toss guesses against the wall and you see which one sticks, so to speak.

If you are feeling industrious, make some recordings. At 5k, a part out would bring you profit, plus whatever you get for scrapping what you don't sell.

The only other thing, in terms of a daily, is that it does have 240,000 miles on it. A maintained Suburban/Yukon Xl is going to go 300 to 500 thousand miles. You are awful near that lower limit. AND it sounds like the differential is eating itself, and it couldn't be fixed by 3 differential swaps. If I didn't have three in various stages of repair already, I might consider something like that.

 

[mountie]

Not a bad price, considering....... Take it to a shop for inspection.