2007 Tahoe Z71 - Rear End Noise

[toddrun]

Hey Guys, first time poster, new member.

My wife has a 2007 Tahoe Z71 with around 70,000 miles on it. A couple of weeks ago I drove it for the first time in a long time and I could hear a humming noise from the passenger rear side. 6 months ago, the brake on the passenger rear wheel locked up, ultimately we had the entire brake system replaced, but it did not seem to be related to that. After trying to diagnose the noise myself, I finally took it in to the mechanic. Bad bearings was the diagnosis.

So the mechanic tore it down, and the rear end, axles and axle tubes were full of metal shavings. He had the truck for an extra day to ensure it was flushed out thoroughly, replaced all axle bearings and reassembled. On test drive there was still a rattle, so he kept it for another day to diagnose.

Diagnosis, he believes with the metal shavings floating around, that it caused undo wear on the differential gears and now they are mismatched causing the noise, and that is needs new gears. He did readjust the gears, not sure what is involved there, but he said he did the best he could to match the pattern, and that there is no movement or play at all.

I drove it to work this morning and heard it for the first time. It is not the same hum, it is very faint at first and gets slightly more obvious after it gets warmed up, and is more obvious at higher speeds. It is still a constant hum at highway speeds, but when I slowed down to turned into more of a constant rattle sound. If I had to describe it, it sounds like a golf ball in a coffee cup rattle, but not very loud, and it is constant and changes with speed changes.

Does this sound like gear wear noise? Does this all sound legit? Would you recommend driving it to see if it gets any better? Or change them now? Any other suggestions or diagnosis?

 

[MO Viet Vet]

It is the gear noise. The metal shavings did their damage. The face of the ring and pinion gears are now scared and causing noise and that pitch will change depending on load. You may be able to drive it that way for quite a while but would not depend on it for long trips. Bad luck. The rear brake problem could have caused the original damage to the axle bearing or the bearing was on its way out at same time as brake problem.

 

[toddrun]

Thanks Raiderron,

Appreciate the reply. I was wondering how long I could drive it that way, and what more damage could be done driving it that way. Probably best to just bite the bullet, dig up another ca$h can from the back yard and fix it right. I was hoping maybe it would wear back in now that it was all cleaned up and be good for a while, sounds like that is not the case.

What will happen if I keep driving it and it get worse? Will it just keep getting louder, but no real damage? Or will it let go and damage more like the housing and axles? Just trying to gauge how soon I should get it back in.

 

[MO Viet Vet]

It will get louder for sure. More heat will build up at the gears causing the surfaces to break down even more and then get louder. Like I said, short trips locally could go for years. Long trips at high speed will accelerate. I would drive it and check the rear diff fluid a lot and change often. Gives you time to save $ for the project. Make sure you find a qualified shop to do the repairs. I would call Yukon Gear and get pricing for replacement parts and get the whole kit. When you do this make sure you do the axle bearings and seals again because as the gears break down they will send some more debris thru there. May even need axles if the bearing land at the axle is pitted. Can get axles at Yukon Gear, also. Do not buy gears made in India or some other backass country. Get the recommended good stuff at Yukon Gear. They know their business. When you bite the bullet do it right with qualified tech and parts. This is not a job for the faint of heart or a first timer.