I am experiencing some cooling problems with my 2002 civic EX. It started losing antifreeze after a 2000 mile trip and I top it off daily. First instinct is a head gasket issue, as it is creating pressure within the cooling system. However I have no deposits on my plugs, no smoke, and no antifreeze in the oil or vice versa. Car has been warm, but never seen above ¾ on the gauge. I have replaced the thermostat and radiator cap just for sake. The car looses antifreeze from pushing out the overflow, and sometimes even blows the overflow tubing off the filler neck. Car idles fine, runs fine, and drives more than 100 miles daily. No rough cold starts, no missing or check engine lights. If it was not for the pressure and fluid loss, I would say the car is mechanically sound. Can anyone please give me an idea of where to start to fix this?

 

It sounds like the head gasket to me. Does your rad fan come on at the correct time?

 

It sounds like a head gasket to me also, however there are no other signs. No overheating, no smoke, no plug deposits, no oil in the coolant, no coolant in the oil, no power loss, and the radiator system holds pressure (even overnight). The fans function fine also. Here's another one for ya, I noticed last night that when I turned on the AC, the temperature actually dropped. Heater and AC both work flawlessly also.