I have a ’98 Honda Civic EX. Recently my temperature gauge has been moving up to around three fourths mark. I’ve changed the thermostat and radiator cap. The radiator fan works, I jumped it, check voltage while the car was on, and I finally hear it today while I was sitting at a stop light. Here’s the weird part, my temp gauge will stay around normal when I have the heater controls on hot, heater off, and the temp gauge will jump up to three fourths when I move the heater gauge to cold, still have the heater off. Car doesn’t heat up when just sitting, just when I’m driving down the highway.
Faulty coolant temp sensors. Replace them both. Double check your fan relays.
July, 6, 2006 AT 8:44 PM
I changed the sensor at the thermostat, not sure where the other one would be located. Fan come's on, but car still warms up beyond the safe zone. Thanks again for the help.
July, 10, 2006 AT 8:36 AM
When you turn the heater on, even with no fan pushing the hot air, this provides another avenue for the hot liquid to flow and release its heat. When you shut of the heat you close that valve and thus the system becomes smaller and because of another problem the engine will run warmer and in your case much warmer and not good. I would check simple things like a collapsed hose. They can look good and still have blockage. Another is a radiator blockage.
Did you say that you replaced the engine thermostat or just the sensor located by the thermostat?
July, 10, 2006 AT 9:57 PM
I replaced the thermostat. The upper and lower radiator hoses are hot when the car has been running, I would guess that they are fine because liquid is flowing through them to cause them to heat up. I'm gonna do another flush tomorrow. Thanks for the reply.