MAINTENANCE EVERY 1000 OPERATING HOURS 31. MAINTENANCE EVERY 1000 OPERATING HOURS All maintenance operations to be performed after 10, 50, 100, 250 and 500 hours of operation fall al- so into this maintenance category. 31.1 COOLING SYSTEM, EXCHANGING COOLANT AND CLEANING THE SYSTEM Danger of being burnt! The coolant is under pressure if the engine is hot. Hot coolant may squirt out during open- ing. Check the coolant level only after the engine has suffi- ciently cooled down. Open the cover of the radiator (ar- row) by turning it slowly so that the pressure can escape. Danger of fire! Antifreeze may ignite at the hot engine!
Wait until the engine has cooled down, before refilling an- tifreeze. The coolant must be exchanged after max. of two years. While preparing the coolant, make sure to adhere to the prescribed mixing proportions to ensure a freezing pro- tection up to -34.6°F (-37°C)! This is also valid for areas with moderate climate. The coolant has to consist of 50 vol.% coolant additive and 50 vol.% water. Only monoethylene glycol and dieethylene gly- col are permitted as coolant additives which are both contained in commercially available standard coolants. If the water contains too much lime, the cooling system may be impaired.
In this case, use a mixture of potable water and dis- tilled or deionized water. 31.1.1 DRAINING OFF THE COOLANT 1 - Switch off the engine and let it cool down. 2 - Turn the radiator cap (arrow) slowly to the side, up to the first fixed stop, and let the pressure escape. Then press down the cover, while proceeding with swivelling. Then, re- move the cover. 3 - Stretch a tube onto the drain opening (1) of the discharge cock and insert the other tube end into the collecting con- tainer. 4 - Open the discharge cock and let the coolant run off. 5 - Close the discharge cock. 75 202 172 75 202 _ 75 202