hi all, had a problem with my 95 jap import overheating. i've read through alot of posts and now have some q's. first off i changed the stat after it boiled over so i could have an air lock, but am starting to think it could be headgasket. would i be correct in thinking that if i fill the coolant and then run the engine with the rad cap off and it starts to overflow that combustion gases are enter

 

sorry hit the wrong key and it posted be for i finnished. would it mean that combustion gases are entering the system or could it still be an air lock. any help would be much appreciated. thanks chris.

 

Right
If you didnt have an airlock in your system to start with, the chances are you wont have now, the system is a sealed system, if you have changed the fluid and have caused an airlock then thats different.
Now, the chances are if you didnt do the top one its the head gasket.
Easiest way to check is to look for hydrocarbons in the expansion tank (oil like droplets in the water) or get a methane tester over the rad and check (with the cap off), if you have methane then you have oil in your water
Also check your pipes, if they are squishy after running, thats air, the sealed system builds up pressure so expands filling out the pipes.
Down side is it sounds like a head gasket about 600 quid and dont forget to have the head skimmed

Tony

 

Just to add when running with the rad cap off a healthy engine will overflow, its supposed to run pressurised.

Since you've changed the stat you must have refilled with coolant, did you have the heater controls to fully hot? If not you may well have an airlock

 

thanks for the help so far. just to add the car boiled over and lost all water under normal driveing. the rad hoses go solid with the top getting hot and bottom cold. the blowers will only blow cold. and the car over heats in about 5-10 min