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Whining humming in four wheel auto and 4x4

Davelem

New Member
Joined
Nov 12, 2018
Messages
7
Location
Midland, Ontario, Canada
Hi sorry if there's a thread about this but could not find anything.
I have a 2003 Z71 I get a humming whining sound coming from what sounds like the drivers side when in 4 wheel auto it speeds up and gets louder when I speed up, I switch back to 2 wheel and it goes away after a few seconds, in 2 wheel drive it rides great no noise or vibrations, all fluids where changed about 25k ago. I just bought it from a friend it wasn't getting used much lately and he started to get a clicking noise from the front intermittently his mechanic couldn't find anything, I had a 200 mile ride home with it and it went away about half way and hasn't come back but he never had this humming that I now have any help ideas greatly appreciated thanks all :B:
 
  In four wheel auto you are going to get some noise.
I would have to look I believe the front is engaged like
having your hubs turned in when in auto. Then the T-case
is engaged or it is the other way around. So you will get noise and
you may feel it in the steering. 

  I'm sure there is more just a little read. 

http://www.chevyavalanchefanclub.com/cafcna/index.php?topic=41895.0




 
I tend to agree with JVZL1, I think all of them have some level of noise in AUTO.  I also think if you always leave your vehicle in AUTO, you will not get as good of mileage as if you drive mostly in 2WD.  The sound means there is at least some level of friction.  This issue is not exclusive to avalanche, a chevy tahoe will do the same thing...
 
Took my mechanic for a ride today to listen to my noise and told me its a hub going. But wouldn't it make the noise all the time and not just in 4 wheel drive ? :help:
 
A front hub will generally make more noise when turning away from the bad hub and quiet when turning towards the bad hub. And yes, it will make noise in 2wd.

In 2wd, the left wheel spins the differential but the right front axle is disconnected, so the front driveshaft does not spin. In 4wd Auto, the right front axle is engaged. Since both axles are now rotating, the front driveshaft rotates and in turn, it spins the gears in the transfer case, causing some hum. Mine gets louder up to about 60 kph and quiets down above 80kph. It's louder when accelerating or decelerating and quieter with no load.

I also wondered if something was wrong when I first got the truck. I changed the oil in both the front diff and the transfer case. The old stuff looked fine with no unusual metal particulates and the noise is perfectly normal according to GM and many other owners. So I stopped worrying about it and have had no problems at all.
 
Thanks buickwagon I get no noise at all in two wheel and no difference when turning,I just started to get a scrubbing noise now only when turning in 2 wheel, fingers crossed its going on the hoist this week.
 
Davelem said:
Found out my problem turns out it's the front differential  (n)  :needhug:

Could be worse.

I've had my front diff rebuilt.

Been quiet ever since.

(y)
 
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