Transfer case problem

[DAVE FERENCZ]

Took the kids for a ski. 4 wheel drive up and down the mountain. Almost home I engaged the 4 wheel drive hi. Crunch sound stopped looked under fluid draining out of transfer case. Do you think It's just a gasket? It was running fine. Had new fluid a few months ago. How badly could I have damaged it...100 feet.

[Shad]

That sound like more than a gasket. I would check it out soon!

[AndyL]

Vehicle information? If it is the NP246 AutoTrac case then they would often grind through the case on the front side. GM went through several fluid revisions with "Special" friction modifiers trying to improve the unreliable design.

My 98 Burb ground through at 98K, bought a GM rebuilt case for about $1400.

[StephenA]

Just replaced my busted NP241 with a used case and popped open the one I took out for a rebuild... Not too tough a rebuild, just waiting for parts. The engagement forks wear after 100k or so & can break off & grind into the syncro, planetary or drive chain & gears. I've heard that some forks are aluminum, but both of mine were iron or steel. The engagement fork has nylon pads on it when new. When those pads go, the fork is metal on metal and grinds down (makes an audible sound in 2wd like a wrench is lying against a spinning shaft or something).
Don't know about the 246, but if yours is an NP241 like mine, the forks are suspect after high milage. Mine shows little to no gear wear or spalling, but the chain was loose, causing a clank after shifting abruptly, and the range fork looked a bit burned in addition to the engagement fork being ground away. It helps to change the synthetic ATF every 6 mos, I'm told they last much longer.
Also, on the mechanical 241's, sometimes a faulty switch on the tranfer case can cause the front axle actuator to engage even though the case is still in 2wd. This means the front drive shaft is not being driven, and the actuator tries to engage the front axle with no spin up & comparable speed coming from the T-case. This results in a washboard like sound which slows with axle speed and then "clunks in" when slowing to a stop and the collar engages the spline. This is also what happens when the shift fork is busted and 4wd is selected. Hope this helps.

[Randee of the Redwoods]

If you have the later Borg Warner case like me(check sig), I've heard the internal fluid pump pickups can work free. The lack of internal lubrication will kill the transfer case.(keeping my fingers crossed)

[StephenA]

The Borg Warner is for the 1 tonners, isn't it? Does this take a different 4wd adapter on the Nv4500? Might be nice to have a 3/4 ton with a Borg Warner T case.