Overheating with a "normal" temp gauge usually means the coolant was low enough that it isn't touching the sensor. Or the head gasket has failed and it pushes the coolant out as it heats up.
Thermostat symptoms are
Stuck closed - Rapid overheating and the radiator stays cold due to the lack of coolant flow.
Stuck open - The engine may never reach operating temperature and you have poor heat.
Head gasket is the gasket between the cylinder block casting where the pistons and crankshaft are and the cylinder head casting where the valves, spark plugs, injectors and intake manifold are located.
To test it you use a pressure test device that applies 15-20 PSI to it and then you wait to see if the pressure drops. Another test is to use a combustion gas test kit. It uses a fluid that changes color if there are exhaust gasses in the coolant.
A quick test that you can do without special tools is to remove the spark plugs from each cylinder, keeping them arranged in order and looking at them. If there is coolant getting into a cylinder it usually will show on the spark plug, it will be very clean on the tip and ceramic that goes into the engine when compared to the other plugs.
Wednesday, May 17th, 2017 AT 10:30 AM