Weird Overheating 87 Civic

I have an 87 Civic that runs superhot on hot days. On cool days, it runs normally. Radiator is fine & has no leaks. Has been drained & filled. Had the heat sensor/relay checked out & that is ok too. Last time it got hot, noticed the fan only came on for about 10 seconds or so & then shut off. I have no idea what the prob may be. Anyone have any suggestions?

the sensor in the rad that turns on the fan may be shot. you can try running the fan all the time (when the car is running that is) by connecting the two wires that go into the sensor in the rad and see if that fixes the problem.

if the problem is still around when the fan is running all the time then check the thermostat (by check i mean replace, they cost about $5), if it's still a problem think about the water pump.

ya do what cvcc said connect the two wires on the fan to like a toggle switch and turn it on or off

Thanks fellas. I'll give it a shot.