I got a 91 150 with a 318. She runs nice and cool around town but once I hitabout 70 mphshe starts heating up. Not overheating, just running hot. I spend 500 to 600 miles a week on the freeway. I'm worried about wearing her out. I love my truck and want to keep her around as long as possible. I have replaced the water pump, thermostat and hoses and flushed the radiator out real good but the problem hasnt gone away. Do I need to get an aftermarket radiator? Anyone know where the best are sold? Or am I just gonna have to ride around with the heater on all summer?

 

Hmm thats a strange one...

does your truck have it's fan shroud still? is the fan operated by a clutch or is it mechanical?

If the shroud is gone, the air might not be sucked through the rad like its supposted to be; if you have a fan operated by a clutch, it might be worn out and not sucking at higher RPMs.

 

A fan clutch will only caust overheating at lower speeds. Once you get above 50mph or so the fan isn't doing anything...I've driven a car on a several hour trip without a fan...just had to keep it moving.

My truck had a similar problem. Ran at a good temp around town and on the highway but if I was going up a big hill or pulling a load it would overheat. Ended up having to put a new radiator in it...almost any parts store can get you one or check online for a good priced replacement. Once a radiator gets enough gunk built up in them a flush will usually not cure it unless you have it boiled out at a radiator repair shop. Then you'll spend the same amount in labor and materials as if you'd just bought a new one in the first place.

Derek

 

If you want to verify if theradiator is bad, just feel around on it after thesystem is warm. If there are cold areas on the radiator, either flush it, rod it, or replace it. If the heat is even all around, i'd look elsewhere for the problem.

 

Cool, thanks.