K-seal < a coolant additive that can give a temporary or lasting fix on weepy gaskets, designed for the K series engine with pourus head problems.
Get a compression test done, tester fits into either spark plug/glowplug hole. Its the only way to give an accurate diagnosis of a head gasket issue, there are many causes of overheating, waterpump failure, thermostat broken or missing, blocked radiator to name a few.....
Andy Spanner
January 2017