Originally Posted by fgsportcraft
I have a 1984 gmc short bed pickup truck. when i bought the truck it had a th400 transmission, well i lost 3rd gear so my dad gave me a 700r4 transmission out of his van when he blew the motor in it. I put it in my truck and i drove it around the neighborhood a couple times and it ran good and then on my way back home the transmission lost all power and the motor revs real high and the truck was barely moving. So i pulled it out and put a th350 transmission in the truck that my uncle gave me. I drove it around the neighborhood a couple of times and it ran good and then on my way home it did the same thing as the 700r4 transmission, but unlike the 700r4 transmission the th350 only has power when it is cooled down, once it gets hot it stops pulling but if you let it cool down it is fine....what could cause this?
Did you flush the Trans lines & cooler when the TH400 went bad?
Did you have the TV/ThrottleValve Cable & Bracket connected and adjusted properly with the TH700R4?
For TH350, fluid Cooler in Radiator may be plugged. Brake Clean & compressed air works well. Flush in reverse of fluid flow.