6.3 Cooling system Care and maintenance work Filling the cooling system z Open the cooling system cap 1 carefully. z Fill up with coolant to the MAX mark on the compensation tank and close cooling sys- tem cap 1. z Switch on heating, if available, and set to maximum so that the heating circuit is filled and vented. z Warm up the engine to operating temperatu- re (opening temp. of the thermostat). ( 51 ) ). z Switch off the engine. z Check the coolant level on the cool engine and fill up to the MAX mark of the compen- sation tank if necessary. 6 35