An aluminium-cored radiator with plastic and taks cools the water, and a plastic expansion tank feeds this. The thermostat housing used on the two wheel drive cars differs slightly from the one used cars differs slightly from the one used on RS 500 and 4 wheel drive engines.

When the RS 500 was designed, one of the many detail improvements that were made was a small modification o the thermostat housing design.

This allows the water to cicutlate around the cylinderhead befor the thermostat opens. The 4 wheel drive engines use a mass produced version of the RS 500 housing.

The engine cooling system also includes a Modine to control the temperature of the lubrication oil.

This is basically a heat exchanger that is fitted behind the oil filter.

The engine oil & cooling water pass through separate channels inside the Modine the temperature of one transferring to the other.

The cooling water warms up more quickly than the oil, so the water initially heats the thicker oil. Once up to opening temperature, the water controls the oil temperature down to the required level.

On the original Escort Coswort, the engine cooling system also cooled the first section of the intercooler. (This is not to be confused with water ijection which is a different concept altogether!) The air temperature exiting the turbocharger can be in excess of 150°C, so the cooling system water at approximately 90°C can reduce this, and reduce the work required by the air to air cooling section of the intercooler.

The turbochargers on the Cosworth range also have water-cooling. This allows the temperature of the delicate core assemblies that contain the shaft & bearings to be controlled and prevent breakdown of the lubrication oil.

So, unlike many ‘normal’ cars where the cooling system simply controlsthe engine temperature, the Cosworth system has further work to do, controlling the temperature of the oil, turbo, and (on the big turbo Escort), the inlet charge.