Audi A6 Engine Lubricant Service Training

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Cooling systemCoolant circuitThe cooling system has two circuits - one for cooling the cylinder block and one for cooling the cylinder head. One third coolant flows into the cylinder block and two thirds into the cylinder head. Coolant flow is regulated by two thermocouples integrated in the coolant thermostat housing. Whereas the short thermocouple probe for the coolant thermostat regulates coolant flow in the cylinder block, the long thermocouple probe for coolant thermostat regulates coolant flow in the cylinder head.Both thermocouples are closed up to a coolant temperature of approx. 87 °C, thus allowing the engine to reach operating temperature more quickly.The long thermocouple probe for the coolant thermostat is open at coolant temperatures from approx. 87 °C to 105 °C and the coolant temperature in the cylinder head is kept at approx. 87 °C. The temperature in the cylinder block can continue to rise.Both thermocouples are opened when the coolant temperature exceeds 105 °C, whereby the temperature is kept at 87 °C in the cylinder head and 105 °C in the cylinder block.