Been working on my 95 here the last few weeks. Today I wired the efan straight to the battery. With the truck idling it will get up to about 220-230 and stay there. The left side of the rad gets hot but the right side stays cold. Heater in cab blows hot. Both upper and lower hoses get hard. Could the Tstat be stuck closed causing the issue?

 

Sounds reasonable. Have you checked to see if the water pump is pumping coolant?

 

I installed a new water pump when I did the plenum fix that was 3 years ago and the truck has not been driven since I installed it. One thing I did notice today was when I gave the engine fuel the temp went up a little bit which I’m thinking is from the increased flow through the bypass hose from the pump. Also thinking if the pump was not pumping it would not build pressure so quick. Correct??

 

Makes sense to me. Try running the engine from cold with the radiator cap removed. You'll be able to see the coolant moving thru the radiator so at lest that way you're sure the coolant is moving correctly n not just barely, ya know?.

 

Did you put in a t stat? Sounds like coolant is not flowing, the t stat may be sticking and not opening fully.

 

If it overheats at idle, something is most certainly wrong. If one side of the radiator is still cold, while the engine is pretty hot, I think you just found your problem.

 

My tstat was installed up-side-down. Possible for you?

 

I put in a new 195 stat today. I have good heat in the cab which I think if the water pump was bad it would not have any heat from no flow through the core.

. But it’s still showing a little hotter then I think it should. But I let it idle for over 30 min and it set at the same temp never moved. Maybe leaning to a bad temp sensor.

 

Either that or the clutch on the fan. Plug a scanner on and see what the PCM thinks the temp is

 

it has an efan wired straight to the battery for testing. Can the obd1 system tell you that info?