Originally Posted by
stndrd
If you want to make sure it's not a headgasket, get the car to operating temp, take out all the spark plugs & stick a screwdriver in each cylinder one at a time and after you have removed it, see if there is any condensation on the screwdriver. If you get condensation on the screwdriver after a particular cylinder, that is the cylinder where the headgasket is not sealing correctly. If nothing shows, try cranking the engine over with no plugs in and see if any coolant shoots up and out.
Otherwise carry out a TK head check on the cooling system to see if you are getting any combustion gases into the cooling system