I have a concern regarding my Honda Civic 1997. My engine temperature becomes elevated (max. temperature) after driving for about 10 minutes. Then, the temperature lowers a bit after a while before reaching max. temperature again. This fluctuation goes on and on.

I checked the fans and water, they are OK. Driving on the freeway for extended time presents no car problems besides the gauge readings I cited above. So my question is what is the problem? Is this just a sensor problem? Can anyone answer? Thanks for your response.

 

If the temperature needle changes direction rapidly. (Like the needle goes from full cold to full hot in less than a second) Then I'd look for electrical problems, or a bad sensor. Are any of your other gauges giving you unexpected output?

Perhaps your car really is running hot. If so, you may have a bad thermostat that opens too late.

You should be able to get troubleshooting instructions for this issue from any good service manual.

 

Hi. Thanks for replying.

My car's temperature needle does not fluctuate rapidly. At ignition, the temperature goes up, becoming elevated above normal, eventually reaching maximum. Strangely, the car shows no outward signs of engine problems even after driving for extended times.

I suspect the thermostat does not reflect the actual temperature of the engine. What do you think? Do you really think this is an engine problem, even though there are no signs of an over-heated engine, aside from the thermostat readings ?

 

if the coolant level is ok then chack thermostat and water pump

 

and is your overfill tank filling up... and is there any steam or anything around there

 

FWIW, if you've never replaced your thermostat, it could just be time to replace it. The thermostat in my 97 failed last year, though it presented different symptoms. Mine was opening at a lower temp, once open it would never really close, but they can sometimes fail in the opposite direction too.

Could be (one of?) the coolant temp sensor(s?). I think you can test them with a multimeter and find out for sure, though I'm hazy on the specifics (it's in the troubleshooting part of the Helm service manual).

 

Can I check the thermostat and the water pump myself? Do I have to go to a mechanic? The overfill tank is not full, but it has liquid in there.