Front end clunk

[TheMyth]

I have a 2004.5 GMC 4x4 and the front end is now making a clunking noise when in 4 wheel drive. It does not make noise in 2 wheel drive or when turning to that throws out cv shafts. The u joints look good on drive shaft. It feels and sounds like it is coming from the center of the front end. Anyone got any ideas? Trying to figure out possibilities before I tear into it. 187k miles on it and most fluids have been changed at regular intervals. Been in 4 wheel many times and just started making the noise yesterday.

 

[04D_MAX]

theres no load on the cv shaft in 2wd still could be the cv's, are the boots torn at all?

 

[TheMyth]

No cv boots are perfect. No tears or even worn spots

 

[04D_MAX]

does it make the noise when the wheel is straight or is it only when the wheel is turned?

 

[TheMyth]

It does it doing both

 

[tanlly]

did you ever figure out where the clunk was coming from. i have the same issue in 4wd only and every time i go to the track i wonder when something will let go.

 

[TheMyth]

Nope still trying to figure it out. It is at the dealership now and they don't know yet. But there are also dealing with the fact I blew my tranny too so it might be a few weeks til I find out

 

[farmtrucklb7]

Oh no! Don't just tell them to fix it before you see the price....

 

[TheMyth]

Already got the price just to diagnose it. Ouch. Hoping the extended warranty I have on it covers it

 

[LBZ]

Moved here.
Sounds to me like a U-joint or a bearing is gone in the front diff. Could also maybe be a few broken teeth on the gears. Be interesting to see what they find.