Well today we had a HUGE HUGE rain/thunder storm here in CT...so to keep my truck going in a straight line when I accellerate, I put the truck in 4 wheel drive. Wow...starting at about 40 mph (going in a striaght line, I know not to make sharp turns in 4wd) my front axle/transfer case/something or other in the 4wd system begins to howl and groan and just make lots of general "gear noise". Now, my truck is new and this is the first time its been in 4 wheel drive. Could that be the issue? It seems my 2005's typical "1700-2000 rpm drone" is compounded by a factor of 10 when the 4 wheel drive is engaged. A friend at work has a 2003 2500HD EC/SB 6.0 gasser and he says his 4 wheel drive system doesnt make any noise at all. (he has the same electronic transfer case that my truck has) My dad's Tahoe does not make any noise either when in 4wd (Auto-4wd or locked 4wd). Its not only irritating (I can live with the normal ~1800rpm drone, but not when its 10 times as loud in 4wd), but its making me parnoid that my 4wd front axle is going to grenade itself in similar fashion to a ford TorqSlip tranny):h . Any ideas? or do I just have to run it more in 4wd and it will quiet out. My frined sudjested that maybe since my Duramax (obviously) is heavier in the front end (than his 6.0 gasser) that its just making more tire noise.

---Ben

I have the exact same truck and must say mine doesn't make that kinda noise in 4wheel drive. I can hear it engage and might hear the transfer case when I am pulling up a steep grade with it. But 10 times as lound sounds like something might not be quite right. Maybe somebody at the factory forgot that extra thick gear oil or something, definitilly get it checked out.

It is pretty common from what I have read and seen. It usually starts making the noise when the torque converter locks. Mine has always made the noise. I checked my transfer case fluid and front diff and both fluids are full. I think it was discussed about more noise in T/H mode.

yeah, DEFINETLY makes more noise in T/H mode, but still makes an annoying amount of noise when not in T/H mode...So its really not a problem? Should I have my dealer look at it? Or just live with it...Wpatrus maybe just got lucky and got a truck that makes no noise in 4wd!!

--Ben

You know it's working if it's making noise. I have the same issue. I went some 50 odd miles at ~60mph in 4 high and it made the same drone the whole way. It stayed together so it is good enough for me.