Four months after I purchased a used 03 civic, it overheated. This started a series of overheating events that has led to replacing the radiator and thermostat. Finally took it to the Honda dealership - they check it for engine problems and the testing came back fine. They did flush the system and replaced the coolant. It was ok for a week, then it started overheating again. When you turn the heater on, it will not heat while idling, only heats when you are driving down the road. I also tried that liquid metal stuff to no avail. We also did a pressure check to see if there were any leaks - NO LEAKS FOUND. I'm told my choices are replace water pump, timing belt - if that doesn't help, pull the head and check for blown gasket and/or cracked head. I need some experienced expertised advice! Thanks!

 

I have the same problem. Does your temp gauge redline at idle and sometimes when going down the road?

 

I don't think you will need to replace your timing belt or water pump because you said your car was running fine after u got it back from the stealership. So its probably something else. You might have air bubbles in the system that developed over a week causing it to overheat.

Does your exhaust look cloudy white? That's a sign of a blown hg

 

The temp guage just goes up about halfway - which seems normal, but when it gets hot, it starts rising to the top. This happens only when you drive it down the road. After it cools off I check the fluid level and it needs some coolant, so I know its going somewhere.

Absolutely no white smoke coming out of the exhaust. A mechanic friend of mine said that if the heater only blew hot air while driving down the road (and not idling), that it may be the water pump not propelling the water good enough to go through the heater core. The higher RPM's made the water pump propell the coolant and therefore through the heater core causing the blower to blow hot air.

 

i suggest First getting all that Quick fix crap out of your system, it does way more harm then good. i would next check water pump for leaks and replace thermostat. make sure the electric fan works to.

it sounds like the thermostat is sticking and not allowing coolant to flow good enough.

 

if it is anything like mine it wont be the thermostat. I changed that and it didnt do anything. My next goal is to see if the heater core is clogged.

 

Take the thermostat out and see what happens.

 

check your fan if it comes on..

 

I really appreciate the response. Since the car's heater blows hot air while driving down the road, wouldn't that mean the thermostat is opening and heater core working?
We put the coolant system under pressure and couldn't find a leak anywhere. The good thing is there's no water or steam coming out of tailpipe and no sign of water in the oil. We do know it is loosing coolant because when it eventually runs hot after driving it awhile, the coolant is low. I'm thinking it's a blowed head gasket or perhaps a cracked head. If it is those two, it certainly is not affecting engine performance, because it runs well.

 

how many miles are on the car, and whens the last time the water pump has been replaced?