2001 Suburban 4x4, grinding under load, transfercase clicking, video, what is it?
 

Hey guys, i recently picked up a 2001 Suburban, 1500, 5.3l 4x4. It had some front end noise when i went to buy it, i determined the driver front wheel bearing was bad, so i replaced both hubs, cv axles, upper and lower ball joints and inner and outter tie rods since they were cheap enough. Got an alignment, and its still grinding differently though.

I have replaced all fluids front and rear, transfercase was Auto track 2 fluid, it was maybe a 1/2pt low when i drained it, slightly brown, no big pieces or anything abnormal. Both front and rear axles had some glitter and older dark brown oil in them. i replaced them first with 75w90 mobile one, didnt seem to make a difference, there is a slight whine under load and when letting off. I replaced with 85w140 royal purple and it seemed to quiet down a little. No big pieces in the oil the 2nd time i drained it, maybe 150 miles later, still some glitter but not much.

Ujoints are getting replaced Friday, i attempted to replaced them, it ended up being a huge pain even with a torch and press, i got one in at the expense of another so im just having a shop do that part. none of them seemed bad when i had them apart. I am thinking either the carrier bearings are going bad, its a low growling under load, or its a bearing inside of the transfer case. I can definitely hear the transfercase if i listen very carefully, but there is a growling once everything warms up, i am just not sure if its the transfercase or carrier/pinion bearing. There is no play up or down at either axle yoke, there is a small ammount of play at the front output shaft for the transfercase, nothing abnormal to me, but the rear output seems to have about 1/16" of play, and makes a weird clicking noise when i push up on it. i attached a video. I am thinking the output shaft bearing is bad and i should start there, i am ok with gear whine, but the bearing growling is not ok with me. The whining seemed to quiet down with the 140w gear oil, the growling was unaffected. Everything sounds like its coming from up front but i know thats not a good indicator.

What do you all think? I am voting for replacing the transfercase first, since i have a clicking at the back and slightly leaking output shaft, and i know they are problematic with pump rub though i cant find any signs of it.

The next step would be replacing front and rear ring and pinion sets, which would be fine because i'd swap to 4.56s to towing since i have about 32" Duratracs on there now.

I know the vehicle isnt worth a whole lot but to me its worth it for the sole purpose of moving my bobcat a half dozen times a year, and for winter driving. And of course i love the LS platform, and the transmissions can be made very strong for very cheap.

Anyway thanks guys, here is the video

Np246 clicking - YouTube