Groaning and vibration from the front diff or axles only in 4wd

[RumorsOFsurF]

I tried searching the forums using several terms, but couldn't find any help, so I guess I'll start a new thread.


While I was at work last night it snowed a couple inches, so I engaged 4 high in my 2003 Yukon(NP246 T Case) when I was driving home. As I was driving, I noticed a noise and vibration that only occured while on the throttle, either accelerating or at a steady speed. Not while coasting. In Auto 4WD, the noise only occurs when the back tires begin to slip and the front kicks in. When I shifted back to 2 high the noise went away completely. I drove around the block when I got home several times, listening to the noise, and it gets much louder when turning. At low speeds (around 5-10mph) it's a groaning sound, and quite noticeable.
Before anyone says it's because I'm in 4 high on pavement, the ground was completely covered in fresh snow, and the traction conditions were low. It is difficult to even move in two wheel drive, and the G80 kicks in at inopportune times when you do and sends you all over the road.


I checked the front driveline and there's no slack as far as I can tell. The front axle CV joints will move a hair when I tried to jiggle them or whatever, but the movement was less than a millimeter...almost imperceptible.


As an aside, in the past I've noticed a VERY slight vibration when turning in 2WD in dry parking lots and such, but no noise really. Most people probably wouldn't even notice it.



So could it be the differential itself? Or could the CV joints be the culprit? It seems like it's the driver side to me, but of course that's where I'm sitting.

 

[Frankhenrylee]

Had the same thing happen a few weeks ago. Tried it the next day on an icy patch and didn't hear anything. Occasionally while in 2wd and the wheel is turned all the way it seems like it is binding up, a little bit like its in 4wd. Very interested to hear the outcome of this. Mines got about 110,000 but doesn't look like the torsion bars have ever been raised. I do have the lean on the drivers side, it almost looks like it has been lowered an inch on the drivers side, cv's are actually a hair lower than level. Doesn't seem like that would cause any damage considering alot of guys max theirs out.

 

[zaathur]

I would try a new cv shaft i have replaced a few 99-06 silverado cv shafts because of
front drive train vibrations and fixed the problem

 

[RumorsOFsurF]

Found out another interesting fact...My Dad's nearly identical '03 Yukon makes the same noise while turning in 4Hi, but no vibration while traveling in a straight line. Weirdness.

I compared them side by side today. I called the dealer and I'm going to take it in to have it looked at on Tuesday. Once again I'm glad I bought the extended warranty. Already had the transfer case replaced, so now the warranty has paid for itself and I'll be in the black if there's something wrong with the diff.

Not sure that's such a good thing that I'm having to repair or replace major drivetrain components all the time.

 

[zaathur]

let us know what it is, how many miles does your have

 

[DaRosa218]

How's the level of fluid in the diff? Mine was doing that in the rear due to low and old fluid. Switched it out to Lucas using the preferred weight of oil and put in limited slip additive. Never heard a noise again.

 

[Frankhenrylee]

Changed my diff fluid today. Front diff is probably F'ed. Drain plug had a chunk of metal along with alot of metal shavings. My brother, who is a parts manager at a local dealership, told me that they don't rebuild these, they just replace with a used part.

ADVICE: If you're looking at a used 4x4 go ahead and pull all of the drain plugs and check em out. I could have/should have passed on this one.

 

[rich5368]

Depending on mileage and how often it was changed by the previous owner, some metal shavings on the plug is normal. They arean't hard to rebuild though.

 

[andrew383]

Its a normal noise of the autotrac case..

 

[04SS99Denali]

slight vibrations/noise is normal when on pavement when in 4hi. when in 4hi your front diff is under load which is why the noise will only come out when in 4. change your fluid if you see alot of metal shavings then start looking for a rebuilt unit. noise from the front is usually not a good thing

edit: just read your post lol. look for a rebuilt unit from jasper or pull one from a wrecked truck at a junk yard