My little joy-buggy (93 del Sol Si) is getting hot when I drive for at least an hour IF it is hot outside and I'm pushing the engine (like 70mph up a grade), on short trips it is fine and I know the fan works properly. It appears that the radiator cap pushed out some fluid last year but it was never run dry (dad the retired pilot borrowed it for a long trip... you'd think he'd have been more careful!!!). He added some coolant but I don't know if he bled the system. Anyway, it continued to run hot on long trips but hasn't lost coolant or power, I've not noticed any smoke (white or any other color, hoping it isn't a head gasket), and I still get ~40mpg. The thermostat was recently replaced but didn't seem to help, and like a dork I didn't ask my mechanic to check the system for air. Other history that may be important... it got very hot going up a grade a few years ago but I noticed before it got to the red and turned on the heater which cooled it down to normal just fine, got the oil changed and the coolant flushed and refilled the next day and they said everything was ok. Turns out the fan had gone kaput, had it replaced, and things were ok for awhile. I've never had another problem on short trips, and I don't make long trips often so it is hard to say how long this has been happening. I'm thinking I should replace the radiator, but I guess it could be the gasket. Any ideas? I don't have tools or time to make repairs myself anymore, and because I'm a woman it seems that mechanics assume I'm an idiot and try to fleece me. Please help?

 

Sound like the only thing in the system you haven't checked is the water pump and the rad cap. Air is a big problem. You can check to see if you have stuff in front of your rad plugging air flow.

 

If it's only on long trips I would lean towards the cap anyway but since you said it "pushed out" some fluid - whether it was into the expansion bottle or out onto the rad itself - that seems like the culprit as it could allow the fluid to boil after a while when it gets hot enough.

Get a new cap.

If it were my car I'd flush the system again just to get any remaining gunk out of it - get the air out by removing the bleed bolt on the upper hose after you fill it (wait until no more bubbles) Next run the engine w/ the cap on the first stop position, not all the way closed, until the cooling fan comes on twice and then add coolant up the the top.

There's a couple other ways to make sure you get the air out of the system, some faster, but that's the by-the-book way for my '92 civic which is a very similar setup to your car.(same engine so prob. same rad)

Make sure your cooling fan works correctly before you run it w/ the cap 1/2 closed, otherwise watch the temp guage.

 

Thanks for the suggestions. I'll get myself a new rad cap and flush the system this weekend. Of course if there is a problem with the water pump, I'll probably be able to figure that out, too. It's about time I spent a little quality time with my car (graduate school=no life outside lab).