mimog3

Hey all, have a 2000 Civic EX that seems to be pushing coolant out of the overflow tank. Did a pressure test which would drop a couple PSI after 10-15 mins with no visible leaks. Did a combustion test via a tester that has a liquid that changes color but the color never changed the whole time. I'm going crazy as i removed the thermostat so the flow of water is constant but its getting pushed out of the overflow tank. I dumped the coolant that was in the overflow tank into the radiator and after a 10-15 min drive it again filled up the overflow tank and pushed it out. Is my assumption in assuming its a head gasket probable? No rough starts, I dont see any leaks. Can a bad head gasket burn coolant and not read on a combustion tester? I replaced the cap with an aftermarket one in case it wasn't allowing flow. Still no changes. Water Pump is working as without the thermostat the coolant is flowing strong. What do you all think and could also recommend. I back flushed the engine block and radiator with no flow issues. Havent tried the Heater core but dont think that would cause issues with coolant disappearing, I also do have heat when the coolant is present.

TomCat39

I think it's possible. You can pull your spark plugs and inspect the piston tops. If one or two are bright and shiny while the rest are blackened with carbon.... it's a solid sign of coolant in the combustion chamber.