Please help guys. I have an 05 civic and my radiator is transferring all of the coolant to the overflow tank. As a result the radiator empties and the overflow tank overflows and spews out of the top. Heater stopped working but Car does not overheat. I immediately took the care to the dealership and they flushed the system and rebleed it. They scanned the ecu and found no codes. Got home and the same problem occurred. What could it be???

 

Right after the cooling system was flushed, did the heater work? If not, the thermostat may be stuck closed. Another possibility is that the radiator cap is faulty and unable to hold proper pressure. Alternatively, the worst case scenario is that the head gasket is blown and exhaust gas is being forced into the cooling system, causing the problem.

 

Yes the heater worked because there was coolant in the radiator.

 

Faulty cap, or a tiny air leak in the hose between the radiator and the "overflow" tank.

Especially look at the gasket in the top of the cap around the outside edge. Or just replace it regardless.

The system depends on a vacuum forming in the radiator and pulling the coolant back out of the tank as the engine cools. The flow is controlled by valves in the radiator cap.

 

I'm not seeing any white smoke at all. What could cause a problem like a blown gasket?? How do I know for sure???

 

Before you concern yourself with the head gasket, replace the radiator cap and look for a leak from the coolant reservoir hose.

 

took it to honda twice... my own mechanic once. they pressure tested it looked for leaks, ran it.. and found nothing..no white smoke, no overheating. how could i know for sure waht it could be

 

You may want to ask the dealership or a mechanic to do compression and leak down tests on the cylinders. Is there any oil in the coolant or coolant in the oil?

 

i havent checked that yet, what exactly am i looking for?