I have a 2001 Silverado 1500 Z71 with the 5.3 liter engine and the automatic
transfer case. It has almost 36k miles.
When I put the transfer case into any 4wd setting (auto, hi, lo) I get a low
howling noise from the front of the truck. There is no noise in 2wd. The
noise is loudest while accelerating but is also noticable when coasting to a
stop. The noise is also louder in 'hi' than in 'auto'. I just bought the
truck so I don't know if it has always done this or not.
A Chevy dealer (Cambridge (MA) Chevrolet) replaced a hub which didn't change
anything. They wanted to rebuild the differential for $1200 - $1700.
Instead, I took it to an independent mechanic and they think the noise is
normal transfer case noise. I also had a GMC technician drive the vehicle
and he thinks it is normal.
Any advice for me?
All three of my last GM's did this...
My '00 Blazer had a mild howl, all of it's 98K mile life.
My old Avalanche did up until about 40K on the clock, then
it almost completely cleared up.
My current truck, an SS, is making the noise too... but it's
mainly while turning, because of the AWD setup.
In both of my old trucks, I just ignored the noise and never
had any issues. All fluids were relatively clean w/no metal
shavings or anything ugly like that in them.
I'd have to say that it's normal...
Sounds like you have already had a number of opinions,
are you just looking for more?
Personally, I'd go with the original Chevy dealer. It's not
normal for these trucks to howl when you put it in 4hi,
but I see and overhaul bad front diffs in these trucks all
the time. It's almost an epidemic in our shop. Usually,
the side bearings go out, you get excessive backlash,
which takes out the gear set.
Has anyone pulled the drain plug on the front diff? Often,
when they are coming apart, you will find all sorts of
metal stuck to the magnet on the drain plug.
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