my cars got a zc (dohc) in it and the last couple of days its been overheating randomly, sometimes when i'm driving but mostly when i'm stopped. i bled the coolant system and i dont have any leaks (fluid is topped up). i check the upper and lower rad hoses and they are both hot after driving. i read on another forum that the rad cap should hold pressure in and when i open it it should make a sucktion sound (releaseing pressure), but mine doesnt. it also said that this could cause the car to overheat. is this possible? also how can i check that my fan is comming on cuz when the temp gauge is high and i pop the hood i didnt see the fan spinning. oh and if i put the climate control heater to hot and turn the fan on max it lowers the temp abit.

 

shouldnt the lower hose be cool because of the thermastat? ive never worked on a zc, only d's, but, is your thermastat working?

 

Yeah, a leaky rad cap will not build pressure in the cooling system. The pressure in the cooling system raises the boiling point of the water in it. If it can't build pressure, the water will boil at 212*. With a working cap the water will still be water at over 212 instead of turning to steam.

 

ok replaced the rad cap and it still overheats but when its overheated the fan doesnt come on. i checked the fan by connecting it straight to the batt and it works so i guess its the fan switch? anyone know where its located and how to test it?