Ok I have a 93civic si (d16z6).I had a problem with water pump so I fixed it and the car was fine for a few weeks.The car started overheating again and the coolant was not hot on the return so I replaced the thermostat as well.All is well for a few more weeks and I go for a long drive and it overheats again only this time im half a litre low on coolant.I cleaned the engine and cant see in leaking from anywhere,but the overflow bottle looked to be full.The temp got up there on the car but I pulled over before any majour damage was done i think!the exhaust looks normal,oil,coolant,ect...all look normal as well.from what i can tell the car only has about 140000km.Anybody have any thoughts on what im lookin at here.

 

usually if the overflow bottle is full the headgasket is gone