Rep Power: 0

Hey y'all, hoping someone can help out here. I have a 2005 civic EX which is not getting any heat when I'm driving slowly or parked. Buddy of mine who's an ASE certified master technician & former Ford mechanic has done everything he can think of to try to figure this out, but to no avail. The only thing that work so far is backflushing the heater core but that only works for a few weeks and then im back to having no heat at low idle again. It's not the head gasket. We got rid of the engine the car had when I first bought it because the head gasket blew twice in six months and now I have another engine that's been perfectly fine. But we do still have little gold particles of stop a leak from the previous owner dumping into the cooling system in ridiculous quantity in an attempt to figure out why it kept overheating; which was obviously a head gasket issue. I'm not losing coolant and the heat works when at highway speeds or in park if I rev the gas and hold it above 2000 RPMs. I'm totally at a loss here. I'd like to get this settled once and for all.

 
Rep Power: 211

How do you know for sure? Did you do a block test? Better yet did you do a leak down test?

Did the previous owner give you service records of head gasket repair? Did you do a headgasket replacement?

Does the blower motor work on all speeds? Sounds like the water pump might be failing (not completedly failed)..still spins but, not as it should. Spins enough at higher revs but barely spins at idle (just enough to not overheat). Other possibilty may be thermostat is suck in a partially open position (half way between closed and open).

Have you tried a thorough flush including removing the thermostat and flushing + back flushing the coolant sytem with and with the block drain bolt removed?

 
Rep Power: 519

LOL!!! That means it's a head gasket.