You need to verify that coolant is flowing through the system. Is the radiator plugged and not flowing water through it? Thermostat installed the right way? Is the thremostat opening?
Beater Red said:I have a '90 Chevy 1500, the Cheyenne. It has 200k and a lot of problems. The 4.3 262 engine is in it. My father replaced the thermostat and if he put it in wrong there is no hope for anyone. I was thinking about running it without the thermostat in it for now just to see if that will help. I'm pretty sure the coolant is flowing. If I turn on the heater at the right time it will cool down a bit. Mostly it will cool dow if I go down a big hill and coast, but as soon as I go up the other side it heats up again. I think my radiator is just full of crap and the flow isn't enough, but I don't know how to fix that.