I have a 1990 e4od with 83k miles on it. It has been serviced reg and lubeguard red added. I installed two hayden rapid cool trans coolers in front of the condensor and after the rad cooler. it runs at 150 around town and maybe 190 on the hwy. When towing a 3k lb trailer yesterday in 90 plus heat (some hills ) doing 60 on the hwy it hit 240/250 degrees. I installed the switch to lock the torque conv but i really did not notice an improvement. I called hayden and asked about changing the t stat to a 160 and bypassing the rad cooler and he said it would not matter. What should i do?

 

What about a problem with the rad cooler? The truck has the original radiator. How would problem with the rad cooler show itself? Would the trans be hot all the time? Maybe I should change out the rad for $100 and give it a try.

 

If your rad cooler is partially plugged, you might not be getting full flow thru it and your other coolers.

If it was my truck, I'd ditch the radiator cooler anyway, since your running a thermostat anyway.

 

There is such a thing as too many coolers. Each one you add, plus the resulting fittings, can reduce the flow of the transmission fluid. This will cause poor cooling performance.

 

I asked Hayden about that and he said two in series is fine.

 

I ordered a new rad to eliminate that possibility. I live in area where it gets very cold so I do not want to eliminate the rad cooler.

 

I hope it works out for you. Please let us know if the new radiator fixes the issue.

 

Think about an external spin-on filter, and a major system flush, even with new parts, stuff can plug it up. Good Luck!