Newish guy has transfer case problems???

[Scotty1122]

First of all, this is my first time posting, so 'Howdy'! I have an 2003 Chevy Tahoe 4x4 with auto ride. 97,*** miles.


My issue is there was a clunking/rattling vibration developing on the tahoe. Checked u joints, wheel bearings etc.(usual culprits) As it got worse(louder and more constant) I rechecked some things and the left front bearing/hub assembly needed replaced.(had some play in it)

This did not help the vibration at all. Could feel a difference in the steering tho. I inspected the driveline again and noticed the rear drive shaft had some slop in it at the transfer case. I could move it up just a bit and it made a slight crunch/pop noise. Obviously this is not good.

Anyone have this issue? Is is just a bearing inside there that can be replaced? 4WD works fine, I just get Vibrations and clunking when feathering the gas, coasting or slowing down. Also on the interstate, if you travel at 65 or higher it gets really bad. The MO' FASTER the MO' BADDER!

Is it for sure the transfer case? (pretty sure) Is it better to replace the whole transfer case or will a new bearing fix it? If just a bearing, any pointers or tips? It has a NP8 listing on the glove box label.

Thanks for any help you can offer.

 

[solored]

im intersted to... MINE does the same thing.. other then at 80kmh-115km then seems to level out.. though when i go really slow like idling you can here a cluink clink clink.. the slower the louder... but yes it does viberate really good at 80kmhi was thinking transfer case to.

 

[Scotty1122]

im intersted to... MINE does the same thing..

If you get up under it and push up firmly on the front of the rear driveshaft where it comes out of the T-case does it click/or crunch? Thats the only slop I can find anywhere. Ujoints all appear to be good.

 

[RumorsOFsurF]

Does your transfer case appear to be leaking? This can be an indicator of the dreaded "pump rub" that's common with the NP246 transfer case. (Autotrac) Mine's already been repaired with some JB Weld or something before I bought it. Mine's in the shop currently because the 4WD isn't working, which may or may not be related. When I realized it wasn't working I crawled underneath to find what looked like a shoddy patch job.

The oil pumps in these cases can wear small holes in the magnesium case and cause a seepage when driving. Usually, they won't leak at rest, such as in the driveway, but only when there's pressure from the oil pump when moving. Often they'll run dry and cause catastrophic failure.

Look for a small pin hole on the back half, and then pull the fill plug(top plug) to check your fluid level. The fluid should be blue and you should be able to stick your finger in and feel it. Don't refill with anything but the proper GM Autotrac II fluid.


Do a Google search for NP246 Pump Rub. Should give you some results.

 

[Scotty1122]

Thanks. Thats good info.

I did come across a article about that, but no leaks. They have a video on Youtube that is a clip from the "Truck U" episode showing the aftermarket plate that is thicker with tabs to prevent it from cutting into the case. The stock plate is apparently too thin and sharp.

A friends trans. shop seems convinced that its the Ujoints and not the transfer case. So I'll gladly take the cheaper route first and replace those. We'll see!