Questionable noise

[rich5368]

So I'm driving my 03 Denali xl and I have a weird noise that sounds like it's coming from under the drivers floor board. It's kinda like a grinding but it's only there under light acceleration and if I'm coasting and then get back into the throttle there is a light clunk. It's AWD so I was thinking maybe the U joints in the forward driveshaft need changed but wanted to see if any of you have run into this before I spend any money.

 

[rich5368]

So I'm reading other forums and some are saying bearings and some are saying the front diff is blown. I did find a thread where one other guy had the same exact issue and the only response he got was that it sounds like a bearing or something. I really hope that the diff isn't jacked. Don't have a ton of money to rebuild one.

 

[cam3439]

Have you check the u-joints? Those are pretty easy to check.

 

[rich5368]

I'll definately check those in the morning. I've been reading a lot tonight and some are making sense saying that it could be the front carrier bearings. It's a whine at part throttle that goes away above about 45mph and when I let off the throttle. Others are saying that they are being told by GM techs that it's normal so I'll have my mechanic look at it but I have a feeling that I'm going to get the run-around.

 

[cam3439]

Have you checked to make sure you're not low on fluids or if they're black as heck?

 

[amaz]

Light whining is normal, but if it's grinding noise, I suggest you to drain front diff oil (drain them to a clean canister etc. so you can see if there is metal in oil). My tahoe made a loud bang few days ago and after that there was loud grinding noise. There was almost a handful of metal from bearings...

 

[rich5368]

So I drained the front diff today and honestly it wasn't that bad. I did look like the previous owner had never serviced it but when I bought the 04 and serviced the diffs they looked just as bad. A few metal flakes and some dust in the oil and it was in need of changing but nothing to say that hey this diff is a goner. Filled it back up and now I have the normal AWD whine and the noise that I previously had. I originally thought a bearing but the noise doesn't vary in pitch or volume at all with varying speed. It's there under light accel and gone on coast and on the highway. I'm befuddled. Could the drive shaft splines needing GM "special lube" cause this noise? I'm going to do the transfer case this weekend. If the diff was never serviced I'm sure the transfer case wasn't either. It's not loud either. My wife doesn't even hear it but I noticed it when I felt a slight vibe in the floorboard.

 

[LEBROND]

hi just wanted to know if you found out what the problem was because my 99 is vibrating like crazy i changed the rear u joints and its still doing it so instead of wasting money again im trying to get some pointers so ill know exact;y what it is

 

[rich5368]

It was the case bearings on the front diff. About a 4 hour job to break it all down and put back together