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Honda Civic 2001 overheating

Hey, everyone! I drive a 2001 Honda Civic EX and have over 248,000 miles. Almost at a quarter million! Recently, the engine has been overheating. The coolant has been leaking and the coolant reservoir would becomes full. I’ve checked out the fan and the fan relay and both seem to be fine. The temperature seems to increase (to redline) during traffic jams and any times of idling. When I blast on the air conditioning, the temperature seems to decrease, but would later increase when the car idles. The temperature also decreases to normal when I sustain my speeds over ~60mph. Also, the temperature will fluctuate from cold to hot to cold. What does this all mean? If anyone has any tips or advice on getting this fixed, I’d appreciate it!
freezing my car, David

You probably have several problems. At this mileage, the radiator and cooling system should have been flushed at least 4 times. If not, your coolling system may simply be partially clogged, reducing the cooling capacity.

Also, the cooling fan may not be coming on when it should. At idling you have the least air flow through the radiator, and you need the fan to circulate that air.

The coolant is leaking and with the reservoir “FULL” you may ahve a lot of air or combution gasses in the sysytem, which would indicate a head gasket leak.

You need a good independent garage to:

  1. Check the cooling fan to see if it comes on when it should

  2. Perform a compression test on the engine to see if the head gasket is intact

  3. Perform a pressure test on the cooling system to determine where the leak is.

  4. Flush the cooling system, if not already done so, to restore the radiator’s cooling capacity. Also check if there are enough fins left on the radiator to dissipate the heat. At that mileage, most cars today are on their second or third radiator.

Please tell this forum what regular maintenance, if any has been performed so far.

If you are lucky you will get away with a new rad and a flushing which will set you back about $400 or so. If there is a head gasket breach, add $900 or so.

At this high mileage many things are close to failure.

You have to find where the leak is coming from, that’s the most important. All the symptoms are an indication of an inefficient cooling system. Possibilities include a faulty radiator fan or temp switch, a bad thermostat, low coolant or air the the system, or a faulty water pump or radiator.

Thanks guys for your tips. The car has received regular maintenance throughout its lifetime (e.g., oil change, fluid flushes, etc). My mechanic did check the fan and it was coming in on time. Also a compression test and pressure test were done. He did not check the fins on the radiator. It is the original radiator. He did mention that he thinks it may be the thermostat that is broken. I love this car and it has taken good care of me. Thanks guys! You guys have been super helpful.

I’d go ahead and try the thermostat first since it’s cheap, but it sounds like the radiator to me. Also, the air conditioner adds load to the engine, so it’s strange that that helps it cool off. Normally if you turn the heat on, that’s what will cool the engine off, as the engine coolant is what heats the air.