I have a 1995 Honda Civic that just all of a sudden started overheating for no reason. There are no leaks from the radiator or hoses. After the car overheated and cool downed, I topped off the radiator with a 50/50 mixture, but the car still is overheating. Also, there are no water leaks either (i.e. from the water pump). I am not a car expert, but I know a thing or two. What would be anyone's guess as to what is causing this? My only guess is the thermostat? I am able to still drive the car with the heater on full blast, while watching the temperature gage. Also, I haven't had the radiator flushed in years, nor has the thermostat been changed. In addition, the radiator cap looks good without any rust or cracks.

Lastly, just before the radiator overheated, I had the air conditioning running for about 20 minutes. Thanks for anyone's wisdom and knowledge into this thread.

 

water pump or thermostat

 

Check if your fan is starting to work when it reaches the appropriate temperature. Start the engine, warm it up to the regular working temperature and, if possible, get someone to look at the fan. If it does not start working when the pointer shows regular working temperature, the options might be:
1. thermostat is dead - need to replace
2. wire from thermostat to fan is disconnected - connect and secure with heat resistant tape or simple wire.
If the fan works, check the pump (or, better, if you're not proficient with that, have a mechanic check it).
Have you changed belts regularely?

Hope I've helped

Lana

 

Could be a clogged radiator or a headgasket leak between the cylinders,bad thermostat.