overheating problem
 

This problem is actually on a car I own but I figured that you truck guys are the only ones who could figure out the problem. Its a cutlass with a 260 olds v-8. Around town it seems to be ok. When I drive it on a trip of about 30-40 miles or more it overheats. I t boils the water out through the overflow tank. I have tried a new radiator cap, checked the timing, I can see coolant flowing through the top flues of the radiator when I take the cap off. Any other ideas?
:bowtie:

when you start it up does the fan blow hard:D if not???its the fan clutch....when cold turn the fan by hand if its not hard to turn thats it,feel the little spring in front of the clutch if its oily?thats it..

also if the thermostat is over a couple years old might be weakening pressure of its spring may wanna change that

Clutch fan is fine because it isn't overheating at Idle. When going down the hwy they don't do anything.

Checkj and make sure the lower radiator hose has a spring in it to keep it from colapsing. put a 180-190 Degree thermostat in it.


If the above doesn't fix it pull the radiator and have it flow tested.

Not sure on that new of a model, but my 69 Cutlass did the same thing. I found that there is a piece of plastic that was suppose to mount under the core support. This piece of plastic actually helped to divert the air flow and actually helped the radiator cool on the interstate. I was also missing all of the rubber pieces that were suppose to help flow the air into the radiator rather then through the fenders.

How did I fix this? Aluminum radiator with dual electric fans. :D Definitely overkill, but it works and I am glad that I dropped that extra weight and got rid of the engine driven fan.

Along with what the others said:

In No Order:

What speeds are you driving at and what engine rpm when its getting hot?

How old is the water pump?
Has it leaked from the weap (?) hole at all?
Belt ok (tight and in good shape)?
It is possible that the pump is not flowing enough to keep the engine cool. Long periods of higher engine speeds will require a water pump in good condition. May be pumping enough around town, but not flowing enough for extended periods of higher engine heat.

Is the car carb. or injected?
When was the last time it was tuned and who did it?
Incorrect fuel to air ratio can cause higher engine temps.

What is your coolant to water mixture?
50/50?

I had a similar problem with a car. It turned out to be a plugged up catalytic converter. The faster I went, the harder it had to work to push the exhaust out, so it overheated. Around town it was fine because of the lower RPM.

BTW, I had a '79 Cutlass with the 260. I called it the "Gutless Supreme" because it had no power at all. :D It was much better after I put a '73 350 Olds in it. It was a direct bolt-in, as is a 455. :eek: