Hi i have a 1994 civic dx completely stock. Ever since i bought the car it had no heat at idle. As soon as i start revving it has heat. I took both hoses off the heater core and put my garden hose up to them to clear it out. I then changed the thermostat. I then changed the radiator. Still no heat at idle. After everything i changed or replaced i let the air bubble out of the system. I have no overheating issues. I am out of ideas. Can anyone give me some possible solutions to my problem?

thanks

 

Does the car heat up when it's idling and then get cold once you start driving down the road? If so, that's a common problem of a thermostat that's stuck open. Did you use an OEM thermostat from Honda? The aftermarket replacements are nothing but junk, and I've never once had luck with them. Does the lower hose get hot? Does the upper hose get hot? Are you sure coolant is flowing correctly through the engine?

 

yep, I had to figure out a few things out at work today and this was one of the things I had to do too, but on a Jimmy, same concept. It is the thermostat gone bad.

 

Upper hose gets hot and lower one is warm but no heat. Car stays at normal temp once warmed up with no fluctuation.

I just installed my third thermostat an OEM one from honda and i still have no heat. After i installed it i let the car idle with the radiator cap off and there was alot of white foam that kept comming up. If i revved the motor the foam would slowly bubble out. This has led me to believe my waterpump is shot and is sucking air in somehow or the fins are creating the foam. I am going to change the waterpump if anyone has any other suggestions it would be greatly appreciated.

 

for anyone referring to this thread for help. It was the headgasket that was causing all my troubles. Gas was escaping from the cylinders into the coolant causing a foam effect. Goodluck to all