A Temperature Gauge measures the thermal state of a homogeneous substance. The measuring system must be brought as closely together as possible with the body to be measured. The gauge operates with a bourden tube in the engine which causes the fluid to rise as the temperature increases. From the bourdon tube sender, oil is pumped to the gauge. This gauge will tell you if your engines coolant is cold, normal, or overheating. The Temperature Gauge is very efficient and useful.