What transfer case on a Suburban 2500?

Rich

Rich

Asshole at large
Joined
Mar 17, 2005
Location
Central PA
Semi-late model Suburban/Avalanche 2500, like '02-'06, with the 8.1L and 4L85E trans - what t-case is on it, and is it a POS, or decent enough for a stock vehicle?

I noticed that unlike the trucks, it has the "Auto 4WD" function, which as I understand, engaged the front diff's CAD, and then only engages clutches in the t-case when slippage is detected.

Something about clutches in a t-case on a 6000lb vehicle with 450+lb-ft makes me nervous.
 
NV246, for the record...
 
Well from personal experience, I believe i've got the same one in my '01 suburban. It actually just went out, and what i learned was that there might have been a design flaw that caused it to leak, as well as forgetting to check the level EVERY week after it started leaking. Apparently they have a problem where some kind of oil pump to recirculate the gear lube in it rubs on a thin part of the case near a gasket i believe and after a while allows it to start leaking. It was a small leak on ours and after it was real low one time we filled it back up and 3 weeks later it was still totally full. Then we forgot and a few weeks went by and it ran dry and locked up. That may have only been a problem on earlier ones tho, and the replacement we bought said it had a permanent fix to that problem and it wont happen again. But a new replacement was still 1000.
as far as clutches tho, i don't think that will be a problem if you just dont use auto 4wd, it still has 4 hi and low right? mine had all 3 options
 
Yeah, there is a pump or something that breaks looks and rubs on the housing. Eventually it'll rub a hole in the case and let the oil out. If this happens while driving on the interstate, you are SOL. Ask Biggy about it, he'll know what issue they have as I think this is what happened to him on his 3500. However, don't know if its the same TC as on the suburban...
 
^both right. the pump in these cases rubs a hole in them over time. you will see fluid leaking from the rear case half around the pump castings. if your worried or want to prevent this, just seperate the halfs, check the pump castings and weld up any slots that have developed. then install a case saver for the pump so it won't happen again. there are at least two types of case savers available to stop this problem.

pretty solid cases other than that. i would also use the dealer recommended autotrak II fluid to fill it since it is a magnesium case.
 
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