...and the stuck open thermostat, a classic sign of an overheated engine. A split in one of the heater hoses (now where have I seen that before) and a failed cooling fan were also found. A new radiator and water pump had already been fitted so the actual cause of the initial overheating concern is still a mystery. Blocked radiator? Failed cooling fan? Split water hose?
A "block test" was carried out to check for combustion gases in the cooling system. This is a sure-fire way of confirming a failed cylinder head gasket. Gases in the cooling system are drawn though a blue coloured liquid which changes colour if combustion gases are detected.
New blue leak detection fluidChanged Colour, bad news!
The cylinder head was removed and sent away for crack testing and skimming.