What happens when you drive a car with a bad radiator cap?I will look into putting that on, as it might help with the problem.
All my tests I've done with this truck has been off highway, on roads that go around 45. So no real highway driving. But today I had to drive 3.5 hours with it on the highway, couldn't go above 65 without it slowly moving back up. The overheating is relative to speed. So it will cool slowly back down under 65, but a lot faster at idle. The radiator shroud I have does have the rubber flaps to help move air through the shroud/radiator at higher speeds.
I did remove the push fan so it is only two pull fans.
The only things I can think of are the waterpump and possible air in the system. If air in the system would cause this type of behavior I will defiantly try bleeding it some more. As replacing the waterpump requires me taking the radiator out due to the limited space.
Just wanted some thoughts as this truck is giving me some major headaches.
Edit: Never thought about this until now, but the possibility that the radiator cap could be bad, I have no clue what type of effect that would cause though.
Because the engine depends on the heat absorption capacity of the coolant in the radiator when you drive a car with a faulty radiator cap the car will overheat. The car overheats because the pressure I the radiator is too low for it to contain all the heat generated by the engine. Symptoms of a bad radiator cap [How to test and Fixes] | Rx Mechanic
Also make sure your coolant to (distilled) water mixture/ratio is correct and no air pockets in the system.