CUCV Worn out TH400 transmission???

[Nate]

I have recently purchased a 1985 2 door military blazer 6.2L with a TH400 it has 93,000 miles on it. It runs great & starts fine no problems there. However this winter I purposely got it stuck in the snow just to see what it would or could do , A favorite pass time of many Wisconsinites. Much to my surprise in a fresh snow pile Not ice. I could not get the tires to spin !? 4WD H & Even in 4X4 low. And then I put it back into 2WD and was just barely able to get the rear wheels to spin. All of these I tried out with the pedal to the floor & with decent RPMs from the engine. And yes the 4x4 works I have checked it out in light mud and I have checked the U joints and drive shafts everything that way is on the up and up. I have the regular stock 31x10.5x15 size tires and yes I do run the vehicle on the road in normal traffic. Although while driving it does not down shift while moving when gas is slammed to the floor? like a gas engine does This might be how they are set up I do not know I only have ever driven this one. When the speed of the truck changes up or down it shifts up and down normally I think? It does shift a little hard It goes into third gear at about 47 MPH according to the speedometer. Is this normally ? Is there any adjustments ? Does this trucks transmission have a vacuum assist or is it all cable driven? Does this sound like a worn out transmission or a gummed up torque converter? I would definitely appreciate any advice or or hints or test to try out before I pull the transmission on this thing. Thanks a lot Nate

 

[Bobert]

Sounds like it might be slipping too much. Before i rebuilt mine, it started slipping more and more until it wouldn't move at all. You should be able to break it loose in gravel just a bit.
47mph does seem a bit high.

I don't know if it would work for an automatic, but to see if your clutch is worn out you can put the front end on a tree, then put it in a higher gear and slowly let out the clutch while giving it more gas.

If the rpms just keep going up, its worn out. if it dies, it's still good.

 

[motormayhem]

Sounds like it might be slipping too much. Before i rebuilt mine, it started slipping more and more until it wouldn't move at all. You should be able to break it loose in gravel just a bit.
47mph does seem a bit high.

I don't know if it would work for an automatic, but to see if your clutch is worn out you can put the front end on a tree, then put it in a higher gear and slowly let out the clutch while giving it more gas.

If the rpms just keep going up, its worn out. if it dies, it's still good.

Ya the tree thing wont work on an automatic since the torque converter wont let it stall since it is always slipping and you also cant up-shift while stopped.

 

[3dubs]

I had an automatic transmission shift hard and at high RPM's just before it left me on the side of the road. You might just want to get it rebuilt and a new turque converter. The slipping sounds more like the torque converter. The TH400 is easy so it is relatively cheap to rebuild. I am going to try to rebuild my own with a kit.

 

[kentuckycucv]

Most Cucv have rotten vacuum hoses.. check the hoses around the injection pump, and the one to the transmission. There are several threads on here addressing this....thanks to these guys my transmission shifts right, after replacing my hoses, im glad thats all it was.

 

[dependable]

Also drop tanny pan and change filter and fluid. This has saved me from what i have thought was a rebuild on two trucks.