- Heat soak is the effect of residual temperatures moving from a hot source towards a cooler place. Heat soak occurs over time and temperatures measured at one physical location may not accurately reflect the overall temperature of the part.
Experiment:
Turn your car off when it is hot, taking note of the temperature gauge position. Wait 2 minutes and turn on the ignition. The temperature gauge reads higher now than when the engine was running. The heat accumulated in the metals of the motor has moved into the now disabled cooling system.