Heat Soak Problems

Your engine temperature is controlled via the cooling system with interplay between heat produced, speed of water pump and engine cooling fan all controlled by a thermostat. When the engine is switched OFF, the cooling system becomes inactive and the residual heat in the engine from the block, head and exhaust manifold are transferred to the coolant and other engine components.  The engine temperature actually increases after a hot engine shutdown. This is called 'afterboil' or 'heat soak' and can be damaging to engine life.

If the head is alloy and the block cast iron, heat soak is a particular problem as they will expand at different rates, and there is a long term risk of head warping, gasket damage etc.

As the graph shows, the typical effect of a conventional cooling system is that over a long period the coolant is almost at boiling point until natural convection and radiation eventually bring the engine and coolant system back to ambient.

For an intelligent cooling system, an electric water pump and electric fan are controlled by engine temperature irrespective of whether the engine is OFF or ON. The effects of 'heat soak' are washed away in seconds as the cooling system continues to do its job whilst the engine is OFF.

To overcome damaging heat soak in your engine we recommend the combination of the Davies Craig Thermatic fan, Electric Water Pump (EWP) and a EWP Dual Controller.