Checking the cooling system (Mercedes-Benz Sprinter 903)

The cooling system should be checked regularly, paying particular attention to the following:

• check the hose connections on the radiator, pump, thermostat housing and heater;
• rubber hoses must not lose elasticity, be brittle or cracked. Old hoses often start to leak or burst when the system is under maximum pressure;
• if the radiator is leaking, then probably one of the thin tubes under the plates is damaged or there is a crack in the plastic tanks;
• the thermostat must be working properly;
• check the serviceability of the fan drive viscous coupling;
• the pump may leak if the coolant pump seal is damaged. In this case, the coolant flows from under the pump through the hole behind the pulley. The pump needs to be replaced;
• the rubber sealing gaskets of the expansion tank cap must not lose elasticity or have cracks;
• if the system hoses are compressed after the engine cools down, the valve in the expansion tank cap is damaged.