Thanks for that very helpful, so where is the air bleed screw located? I know there is a bleed screw above the thermo housing to let air out when adding coolant, but I’m guessing you don’t mean that one. Took out water pump today and it’s working fine and turning freely, so I am sure that’s not causing the over heating. Only thing left to check is the thermostat itself, is it opening and closing at the set temperature it should? Should I take it out to see? Pop it in hot water with a thermometer and see if it opens etc etc?