Engine Cooling problem
1992 Chevy Silverado V8 Four Wheel Drive Automatic 150000 miles
I have a 92 chevy truck with a 5.7, I use it for snow plowing and have for years. But it overheats on the freeway and is getting worse. I have replaced the thermostat with no luck and flushed the radiator and no rust came out and has good flow. When it overheats as soon as I pull off the freeway the temp jumps back down really quick. It does not overheat in town?
Have you checked all the shrouds. Even the bottom skid plate acts as way of directing air across radiator, and cause overheating if not installed. I would then check the cooling fan clutch to make sure its not freewheeling when warm. If that test ok I would next check water pump. Sometimes the impellor fins break causing the vehicle to not circulate coolant good at higher speeds.