Cooling System: Description and Operation

Cooling System

Engine cooling on the MINI comes in two forms, although the basic layout remains the same. Both systems use a 50/50 coolant solution with standard Kevlar reinforced EPDM (Ethylene Propylene Diene Monomer) cooling hoses.

Cooling System Operation
When the engine is cold the thermostat is closed, preventing the coolant from circulating through the radiator. Coolant is able to circulate through the heater core, expansion tank, and on the MINI COOPER S, the oil cooler.

the MINI COOPER S has a pressurized expansion tank, and allows coolant to enter the top via the heater core pipe, and exit the bottom of the tank to join the heater core return pipe.
As the coolant temperature increases the thermostat gradually opens. This allows a bleed of coolant from the bottom hose into the cylinder block via the coolant pump, and allows hot coolant to flow to the radiator via the top hose. the flow of hot and cold coolant is balanced to maintain the optimum engine temperature. When the thermostat opens fully, the full flow of coolant passes through the radiator.



Radiator

the radiator installed in the MINI COOPER (COOPER S) is a conventional cross flow type. It is constructed from aluminum tubes, wavy corrugated cooling strips and plastic end caps. Coolant flows from the top left to the bottom right (viewed from the front of the car).

There are two radiator arrangements for the MINI COOPER and only one for the COOPER S.


Heater Core
the heater core is constructed of aluminum and is of conventional design.


Coolant Fan




the Coolant Fan is a nine bladed fan measuring 400 mm in diameter, driven by a 350 watt motor and controlled by the EMS2000. This system has two fan speeds.

Low speed is switched on at 105�C coolant temp and off when the temperature drops to 101�C.

High speed is switched on at 112�C and remains on until the system coolant temperature drops by 4�C at which point the system will revert to Low speed.

the cooling fan will also operate on Low speed when the Air Conditioning is switched on and system pressure reaches 8 bar. Should the Air Conditioning system pressure rise to 18 bar, the fan will automatically run on the High speed.

Oil Cooler (MINI COOPER S)

the MINI COOPER S is fitted with a plate type oil cooler mounted directly onto the oil filter housing. Engine oil from the filter housing and coolant from the hoses flows through the cooler tubes adjacent to each other. This process takes place continuously: there is no thermostat control. the inlet and outlet pipes are connected in parallel with the heater core pipes.