Tinkerbell_too

The car is a 2003 Honda Civic LX 4 cylinder manual transmission with 90,000 miles. We did do a search on here, but are to the point that we need some feedback.

We were out shopping about an hour from home yesterday and were sitting in a parking lot waiting to meet up with a friend. Heat was on and car was just idling. After 10-15 minutes, we started to smell coolant and noticed a small amount of steam coming from under the hood. The temperature gauge was still at normal running temperature. Popped the hood and checked...the car was spitting coolant out of the overflow tank and the fans were not on. The temperature outside was approximately 45 degrees. Since we were an hour from home and it was all highway driving, we just kept an eye on the temperature gauge...the car didn't overheat.

This morning, we got up and decided to do some checking. The outside temperature is 54 degrees. First, we checked the fuses. Both the coolant fan and a/c condenser fan are both fine. We topped off the coolant. Between the overflow tank and radiator, the car only lost a half gallon, if that. Started the car and turned on the a/c full blast. Both fans came on. Let the car run about 20 minutes to check and see if the coolant level would change. Once I was satisfied, I put the cap back on and turned off the a/c. The car ran for about 10 minutes without a/c on and the fans never kicked on. The temperature gauge still reads at normal running temperature.

I would assume that the car had run long enough that the fan should have turned on..is that correct? I am wondering if one of our sensors is bad. There's a sensor at the lower radiator hose and a sensor on top of the block by the upper radiator hose. Is it possible that one of these could be the culprit, or is there something else I should look at?

gearbox

iTrader: (95)

well first off, the radiator fan is not really that important for cooling the engine, esp in winter (ive never had the fan turn on below 60F at idle). it usually only comes on in the summer when outside temps are 80F or higher at idle. in the winter you could disconnect the fan and be perfectly fine. and as you said, the car was not overheating as it might if the fan was bad and not turning on. also there is only one fan that turns on when coolant gets too hot. the second fan (actually both together) will come on when the a/c is used so the condenser gets enough air. the radiator fan sensor is the lower one (closer to the ground) and it could be bad, but again you would never know in winter. i hate to say it, but if coolant is being thrown out of the overflow, usually it points to a bad headgasket. i would try to replace the radiator cap first tho with a new one from honda (not a generic one) to rule that out.