Expert: Van - 12/10/2005

Question
Hi,

I have a 2002 GMC Sierra with push button 4x4. When the 4x4 is engaged, there is a substantially loud growl from the front end.I took it to the GM dealer and they replaced the bearings in the front diff(they were pitted), but the noise seems louder now than it was before. They inspected the crown gear and claimed it looked fine and that I should just get used to the noise. It doesn't matter if I am on dry pavement or snow/ice, the noise is the same.The noise is loudest at low speed and seems to get quieter as you accelerate. Any ideas about what might be causing the noise and should I be concerned about doing more damage?  

Answer
Hello Robert,
There should NOT be a growl that you have to get used to.
First of all, is there any chance it is still under warranty?
Get that dealership to take you for a ride in a different Sierra with 4X4, and see if it has the noise. I can tell you it won't.

One thing to check is the wear on the tires. If the rears are considerably more worn than the fronts, for example, then they will be turning at different speeds, and could cause them to be working against each other.
I would expect it to dissapear on ice though if that were the case, so it must be internal.

I think you should return to the dealer and insist they fix it.
If they really replaced the bearings, then they were completely inside the diff, and it should have come out of there essentially as a brand new one, which doesn't have a growl.

Van