Check cooling system

Leaks in the cooling system and the function of the pressure relief valve in the system cap can be checked with a commercially available tester.

• Bring engine to operating temperature. To do so, drive until the coolant temperature gauge in the vehicle shows normal coolant temperature.

• Check coolant level, top up if necessary, see chapter 'Maintenance'.

• Open cap on expansion tank.

Warning: risk of injury! If the engine is hot, place a thick cloth over the cap before opening it to avoid scalding from hot coolant or steam.

Remove cap only when coolant temperature is below +90 °C.

• Tester - 1 - with adapter - 2 - attach to the filler neck of the coolant expansion tank. Use the tester's hand pump to build up a pressure of approx. 1.0 bar (diesel: 0.8 bar).

  If the pressure drops within 10 seconds, locate and repair the leak. The leak can be identified by escaping coolant.

• If the pressure drops without any coolant escaping, an internal coolant loss in the engine is indicated, for example due to a defective cylinder head gasket or a cracked housing.

• To check the expansion valve, attach the pressure tester - 1 - with adapter - 2 - to the radiator cap.

  Use the hand pump to build up pressure and determine the pressure at which the valve opens. If necessary, replace the cap. Nominal value: 0.98 bar (diesel: 0.78 bar).

• Remove the pressure tester and unscrew the filler cap.

  If the rubber seal is damaged, replace it.