My rebuilt transmission overheated and died after one year. Under warranty it was replaced with another unit, torque convertor, etc. This tranny lasted 3 days before overheating and dying. They decided to bypass the stock tranny fluid cooling system and install a fluid cooler. He said he thought the lines may be clogged but he admitted he was at a loss if this didn't solve the problem.

What would cause two transmissions to overheat and die like that? Clogged line? Something else? We're not talking drag racing the car either. Normal street/highway driving, with normal factory shift points. Will the fluid cooler likely solve the overheating/dying problem?

I did have a problem with the original governor on the first rebuilt unit. It was stuck the first couple days(did not know what "stuck" was or that it was a problem at the time), became unstuck and was fine for a year. When they dropped the tranny to replace the rear main, they replaced the fluid. Governor got stuck again. They replaced the governor, then the tranny died a week later from overheating. Replaced under warranty and tranny died again 3 days later from overheating. That was also a completely rebuilt unit.

 

Bad rebuild and/or torque converter clutch not locking up.