Front diff / transfer case?

[OneShotOneKill]

hey guys,

so i need some opinions, first off i have a 2006 extcab z71 / 4L60E trans / NP8 T-Case /

Over time i have started to get a howling noise from the front end that is intermittent in 2wd, at this point in time it is VERY obviouse in 4WD while turning.

while in 4wd and going in a straight line it is more noticable than in 2wd but only slightly.

the real issue seems to be when the front diff is under load (4WD and turning) it creates a loud howling noise and feels like the CV axles are binding.

I got under the truck and checked the CV axles, passenger side seems fine but the driver side where it bolts to the output on the diff has a small amount of play and i can see a tiny amount of fluid coming out, not enough to drip just enough to see.

i brought the truck to a shop that i've used for 15 years and I'm starting to get frustrated- It has been 3 separate trips to the shop now, they tried telling me it was road noise from the tires until i rode with a tech and reproduced the noise.

today (3rd time to the shop) 2 Techs rode in the truck and the said they thing it could be the transfer case and their advice was to replace the fluid because the fancy np8 has "clutch packs" and this could be the issue.

Realistically a fluid change isn't going to solve the issue.

what do you guys think? could this be a simple bearing issue in the diff or am i looking at a problem with the gears? does the front have carrier bearings like the rear? It's been about 3 degrees in the morning lately so I'm not really excited about the idea of being on my back in the driveway trying to figure this out. any help is appreciated.

here's a link to the build sheet on my truck with all the options if it helps.
http://www.compnine.com/mycar.php?id...160750d21646e5

[newdude]

The AutoTrac cases have been known actually to have noises/shudders that are cured by a fluid change of the transfer case. Was very common on the S/T trucks (Blazer/Jimmy).

 

Perhaps you have a bad wheel bearing? Seeing it makes noise in 2WD, if you drive in 2WD and "slalom" the truck left and right, does the noise change/go away/get louder to a certain direction? Wheel bearings can also make tons of noise when 4x4 is engaged as well.

[OneShotOneKill]

I'm sure it's possible but I've replaced both the driver and passenger side hub bearing assembly's over the past 4 years. and when they went bad it sounded completely different from what I'm experiencing now.

 

I'm figuring it has to be more related to the front differential. My guess would be if it were mainly the tcase that it would make the same amount of noise regardless of going straight or turning.

[Nanotech Environmental]

I'm sure it's possible but I've replaced both the driver and passenger side hub bearing assembly's over the past 4 years. and when they went bad it sounded completely different from what I'm experiencing now.

 

I'm figuring it has to be more related to the front differential. My guess would be if it were mainly the tcase that it would make the same amount of noise regardless of going straight or turning.

I have a similar issue that's been going on with mine for a while. It only does it when off the power & coasting, such as going downhill. 2wd or 4wd. Same truck and driveline as yours. It's definitely not wheel bearings on mine, as they have both been changed recently.

There was another poster on here recently with a similar issue as well. Not sure if they figured out the problem or not.

[OneShotOneKill]

Figured I would refresh this topic instead of creating a new thread. the Leak on the front driverside differential seal has gotten worse and I figure if Im going to replace that i might as well replace the needle bearing/output shaft bearing right behind that and see if it helps the noise go away at all.

 

Im wondering if anyone can point me in the direction of what part number i need?

 

I've been looking at rockauto and a few other places and can't figure out if i need the SCH208 bearing or the B2010. any ideas?

 

http://www.rockauto.com/en/catalog/chevrolet,2006,silverado+1500,5.3l+v8,1432418,drivetrain,axle+shaft+bearing,1664