Hi, Ive got an 1987 4x4 with the 22r. I bout the truck several months ago and have since restored it to its original condition. Since I bought the truck the engine never gets but a quarter above the cold mark and this was in the summer when it was 90 degrees out. I replaced the thermostat about 4 times thinking it was stuck open. That did not fix the issue and now that it is cold I have little to no heat. Ive bled the cooling system 5 times for thirty min running at 2500rpm. Ive currently got a thermostat that opens at 195 and the only thing that seems to keep the engine warm is placing a piece of cardboard in front of the radiator. Really looking for a more permanent fix than a piece of cardboard. Also a note I can run the engine for 45 min after driving there is no pressure in the system can take the radiator cap off as if the engine was cold no leaks and it has a brand new radiator with hoses no coolant leaks anywhere. Not really sure what else to check any help would be greatly appreciated.

 

Since you have replaced the thermostat 4 times you either have really bad luck with thermostats or that is not the problem. My guess would be you have a fan clutch that is locked and not freewheeling like it is supposed to when it is cold. Grab the fan when its cold and try to spin it there should be some resistance but not a lot. You said the radiator is new how about the cap?

 

The fan clutch was seized up and I ended up replacing it and the temperature seems to be at a happy place. Now the adventure of fixing my brand new starter begins took it out for a drive went to go do an errand and now my brand new starter spins but won't engage the flywheel, just spins inside the starter. Even tried jumping it and tapping on the solenoid.

 

Hopefully its just the starter and not missing teeth on the flywheel. Glad you got the cooling problem fixed.