How to Replace the Coolant Thermostat on a Volkswagen Golf II

To replace the thermostat on a Volkswagen Golf II petrol model, start by disconnecting the negative terminal of the battery and opening the expansion tank of the coolant to release any residual pressure. Remove the air filter cover and drain the engine coolant into a container placed under the radiator; this fluid is toxic to animals and must be disposed of at an authorised centre.

The thermostat is located on the engine cylinder head, near the inlet of the lower radiator hose. Loosen the hose clamp and detach the hose from the thermostat, then unscrew the two screws securing the thermostat cover to the cylinder head.

Clean the sealing surface carefully on both the cover and the cylinder head. You can find the new thermostat (Magneti Marelli) complete with a gasket on Amazon with code B084NFMC22 for £6.44 plus £4.99 shipping.

Place the new gasket and then the thermostat with the tab facing upwards, as the previous one was installed. Tighten the nuts.

Reconnect the coolant hose, refit the air filter cover, close the radiator drain plug, fill the coolant in the reservoir to the "max" level, start the car and set the cabin heater to maximum temperature and minimum fan speed to expel air. Top up the coolant until the engine reaches operating temperature and the cabin vents blow warm air. Finally, replace the cap on the expansion tank and turn off the engine.