No forward or reverse movement at running temps

[readyman]

My 1985 HMMWV is a garage queen with about 3000 miles. It always starts and runs perfectly for the dozen or so local events. Saturday I was running late to an event a few miles away and stomped on it from all the lights, I noticed there was a lot of rpm's but no acceleration or increasing speed. When I got to the event I could not move the last 15 feet to my 'spot' even at full rpm's, creeped at 1/10 mph. Well 6 hours later and all cooled down... I made it back home using slow acceleration and speed. Another NICMVPA club member followed me home.

The ATF is the original 31 years old - cloudy, opaque and slightly pinkish/brownish not burned. My pushed hot transmission didn't work but a 'takin it easy' driving technique did.

Question is; Does 'old' ATF loose it? and cause slipping. There's not enough miles or wear and tear to warrant dropping the pan, and the fluid isn't dirty anyway(it just doesn't look right).

NP218 TCase.

Update: Vampire Disease.
ATF was sucked into the TCase. Previous owner must have kept filling the tranny it was 2X overfilled.

 

[kojo0513]

Maybe swap out the ATF?

 

[Dock Rocker]

I would definitely drop the pan and see how much metal you in it. Most likely you have a piece of gunk or trash that broke loose and is lodged in the valve body.

Letting a transmission sit is almost as bad as running it to hard.

At the least take it to a shop and get it looked at. It will not heal on its own.

 

[readyman]

I would definitely drop the pan and see how much metal you in it. Most likely you have a piece of gunk or trash that broke loose and is lodged in the valve body.

Letting a transmission sit is almost as bad as running it to hard.

At the least take it to a shop and get it looked at. It will not heal on its own.

Yeah, 13 years after it was delivered the Marines sent it for an IROAN rebuild with 17 miles on it.

 

[101coolcars]

Trans fluid and filter should be changed on a regular basis for long trans life, especially in a heavy vehicle or off road use. I usually change it out every 2-3 years or after a big overheating event or if it smells burned. Heat and bad fluid are tranny killers. If fear the damage may already be done. There is a big magnet in the bottom of the pan to catch metal particles.

 

[readyman]

Trans fluid and filter should be changed on a regular basis for long trans life, especially in a heavy vehicle or off road use. I usually change it out every 2-3 years or after a big overheating event or if it smells burned. Heat and bad fluid are tranny killers. If fear the damage may already be done. There is a big magnet in the bottom of the pan to catch metal particles.

And 'Old Age' ATF?

 

[readyman]

It was the Vampire Disease.
ATF was being sucked into the TCase filling it to the vent. The previous owner must have kept filling the tranny with ATF as well, it was 2X overfilled more than it should be.

 

[Retiredwarhorses]

It was the Vampire Disease.
ATF was being sucked into the TCase filling it to the vent. The previous owner must have kept filling the tranny with ATF as well, it was 2X overfilled more than it should be.

i have had this issue on several customer trucks...the key is simple, once your tranny slips, STOP!
anything after that is just ruining the Trans clutch plates, that equals rebuild.
as far as the tcase, just loop the Tcase back to itself and same on the 2 tubes till you get it fixed.
you might want to look at a 242 TCASE upgrade at this point...as well as a tranny rebuild.

 

[readyman]

i have had this issue on several customer trucks...the key is simple, once your tranny slips, STOP!
anything after that is just ruining the Trans clutch plates, that equals rebuild.
as far as the tcase, just loop the Tcase back to itself and same on the 2 tubes till you get it fixed.
you might want to look at a 242 TCASE upgrade at this point...as well as a tranny rebuild.

Thanks.
After looking at the ATF flow diagrams in the manual that's what I came up with as well. I'm in the process of doing that now. I'm going to try a higher temp synthetic to keep the temp down, and monitor the transfer case temps.
I might not need the cooling loop as much as I think.