2006 Mercedes R-Class Owner's Manual - Page 352

Operation Engine compartment Coolant level The engine coolant is a mixture of water and anticorrosion/antifreeze. To check the coolant level, the vehicle must be parked on level ground and the engine must be cool. Warning! Using a rag, turn cap 1 slowly approximately one half turn counterclockwise to release any excess pressure. Continue turning cap 1 counterclockwise and remove it. Coolant level 4 is correct if the level: for cold coolant: reaches the top of indicator wall 3 visible through the filling opening for warm coolant: is approximately 0.6 in (1.5 cm) higher Add coolant as required. Replace and tighten cap 1. For more information on coolant, see the "Technical data" section ( page 525). Using a rag, slowly open the cap approximately 1/2 turn to relieve excess pressure. If opened immediately, scalding hot fluid and steam will be blown out under pressure. Do not spill antifreeze on hot engine parts. Antifreeze contains ethylene glycol which may burn if it comes into contact with hot engine parts. G In order to avoid any possibly serious burns: Use extreme caution when opening the hood if there are any signs of steam or coolant leaking from the cooling system, or if the coolant temperature gauge indicates that the coolant is overheated. Do not remove pressure cap on coolant reservoir if coolant temperature is above 158°F (70°C). Allow engine to cool down before removing cap. The coolant reservoir contains hot fluid and is under pressure. 1 Cap 2 Coolant expansion tank 3 Indicator wall 4 Coolant level 351