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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29515
Experience:  GM Grand Master Technician 2007. 14 years experience.
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Chevrolet Silverado 1500 Z71: My 99 Chevy Silverado Z71 roars

Resolved Question:

My 99 Chevy Silverado Z71 roars in the front end without being in 4WD. I just put new rotors, wheel calipers and brakes and the noise is still there. There is a small leak coming from the differential on the drivers side but there is no slack in the CVC joints.
Submitted: 5 years ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 5 years ago.

GM Tech (Cam) :

Hello, I'm Cam. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.

GM Tech (Cam) :

Does the nose chance when you turn side to side?

Customer:

no

GM Tech (Cam) :

OK I suggest checking the wheel bearings. Lift the front end and grab the tire at the top and the bottom. Push and pull on the top and bottom of the time and see if you can feel any movement other than the flex of the tire. Also try turning the tire. You may year the noise if the bearing is bad enough. If you find something, replace the wheel bearing assembly.

Customer:

I have tried that and there is no play or noise when I move the tire. But also when I'm driving left to right there is no clicking noise in 4WD or 2WD. The roaring noise gets faster and faster until about 45 mph and then it gets quieter.

GM Tech (Cam) :

Did you try rotating the tires?

Customer:

yes-- It doesn't sound like it is coming from the tires. It sounds like it might be coming from the transfer case.

GM Tech (Cam) :

What is the condition of the fluid in there then?

Customer:

It is leaking around the seal on the drivers side so it is probably low.

GM Tech (Cam) :

Take the front drive shaft out, tell me what happens when you drive it.

Customer:

On both sides?

GM Tech (Cam) :

NO the shaft from the transfer case to the front diff, not the cv axles.

GM Tech (Cam) :

you cannot run with them out as they hold the bearings together.

Customer:

I just realized it is leaking from the differential not the transfer case. Sorry--

Customer:

Should I still take the front drive shaft out?

GM Tech (Cam) :

Yes take it out and see .

Customer:

OK -- thanks -- If it still roars, is it the differential bearings? How do we get back to you?

GM Tech (Cam) :

If it goes away it is in the diff, and you will feel it as you turn the front, if not then the transfer case.

Customer:

Ok- thanks

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