I have a 2001 Civic EX with a '04 engine, it is NOT tuned in anyway, and the problem I am having is the engine overheats whenever I use the interior heater. That is the only time it overheats. I had a compression test done on the cylinders and they are all holding at 160psi. I have replaced the thermostat, the timing belt, the radiator cap, took out the heater core and pressure tested it at a shop. Tha A/C compressor clutch got fried when i put newer engine in so there is no A/C hooked to engine. I am not getting fluid inside the cabin area, not that I can find. I am at a loss on what to check or do next. I had a mechanic tell me it was headgasket without a doubt, if that is so then why are all the cylinders holding such high PSI? Please help I need this car back on the road ASAP!!!! Thank you.

 

Your engine overheating it should not be connected to the compartment heater,it's got to be a separate issue.

 

do u got any bubbles in ure coolant did u bleed it??

 

i wanna know this too.