2003 Silverado, front differential noise

I recently purchased a '03 Z71 silverado w/ 4 wheel drive. While out in the mountains I had the chance to use 4wd (4 hi) but noticed what sounded like
a grinding or rubbing noise coming from the front end, more pronounced when turning or accelerating. The noise was not constant, but was matched to the rotation of the wheels. It was similar to the sound a worn out brake pad makes against the rotor. I am going to take it to the dealer to have it checked out but wondered if anyone had any ideas what could be causing this. The noise is gone when in 2wd, and the truck performs great otherwise.
thanks much
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its UNDER WARRANTY
: I recently purchased a '03 Z71 silverado w/ 4 wheel drive. While out in the : mountains I had the chance to use 4wd (4 hi) but noticed what sounded like : a grinding or rubbing noise coming from the front end, more pronounced when : turning or accelerating. The noise was not constant, but was matched to the : rotation of the wheels. It was similar to the sound a worn out brake pad : makes against the rotor. I am going to take it to the dealer to have it : checked : out but wondered if anyone had any ideas what could be causing this. : The noise is gone when in 2wd, and the truck performs great otherwise. : : thanks much : :
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Sounds like CV joint to me:-)
Don

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"Steve Symms" wrote

There are a few bulletins out concerning front axle and t/case problems on these trucks. Your symptoms don't quite match the bulletin symptoms, but that means nothing. There have been a lot of problems with the front diffs in these trucks....and they often end up taking out the t/case with them. Get it checked it out at the dealer and see what they come up with. For 2003, there is a procedure out to replace the t/case encoder motor sensor, and reprogram the TCCM. One of the four symptoms does happen to be "grinding noise is heard from the front axle."
They should also check the front axle engagement sleeve for wear problems. Bulletin number is 03-04-21-001C
Ian
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. . . . snipped-for-privacy@hotmail.com (shiden_kai)
There are a few bulletins out concerning front axle and t/case problems on these trucks.
Your symptoms don't quite match the bulletin symptoms, but that means nothing. There have been a lot of problems with the front diffs in these trucks....and they often end up taking out the t/case with them.
Get it checked it out at the dealer and see what they come up with.
For 2003, there is a procedure out to replace the t/case encoder motor sensor, and reprogram the TCCM. One of the four symptoms does happen to be "grinding noise is heard from the front axle."
They should also check the front axle engagement sleeve for wear problems. Bulletin number is 03-04-21-001C
Ian ============== you know.......
good information is good information.
Good Insider information is priceless.
marsh monster ~:~thinks Ian ..IS...mr. goodwrench~:~
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Ian can get a big head, now. I KNOW he's Mr Goodwrench!! .
(shiden_kai)

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Ian,
Thanks very much for the info, I appreciate it.
I stopped at the dealer today, and the genius there says "its normal, and is being caused by clutch plates in the transfer case (or differential, cant remember exactly what he said now).. Yah, right. I'll check the TSB you mentioned below and take another run at them.
I realize its under warranty, but I dont want to be 50 miles from the nearest town on some snowy backcountry road and have the front end go t/u on me.
Thanks again Steve

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Differential clutch chatter is more pronounced in tight turns. Been that way for the past 40 years that I'm familiar with. There used to be an oil additive made from whale oil that is no longer available. Never saw a differential break do to the normal chatter.
Dale P...........

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"dale peterson" wrote

This is a different scenario. You are thinking about a limited slip rear axle. The OP was talking about noise from the front axle which would not have a limited slip. On the newer "active" transfer cases, there is a clutch pack in the transfer case that is modulated to apply torque to the front driveshaft when needed or commanded...depending on what mode the t/case is in.
Ian
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Correct, in my case there is no noise in 2wd but the grinding/rubbing noise is present when set in 4HI, regardless if accelerating or coasting. I would think that if it were caused by the clutch pack the sound would cease when accelerating. The dealer thought I had the 4wd selector (electric switches) set to "auto 4wd" which I didnt, and that doing that would explain the noise. I just bought this truck last month so would hope that the transfer case or differential issues identified in late 2002/early 2003 would have been addressed already by Chevy. I'll keep looking for that TSB you mentioned and see if it fits with this situation like you say.
Thanks again gents Steve
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