2004 Mercedes CLK-Class Owner's Manual - Page 287

Operation Engine compartment The coolant level is correct if the level for cold coolant: reaches the black top part of the reservoir for warm coolant: is approx. 0.6 in (1.5 cm) higher Add coolant as required. Replace and tighten cap. 1 Coolant expansion tank Using a rag, turn the cap slowly approximately one half turn to the left to release any excess pressure. Continue turning the cap to the left and remove it. More information on coolant can be found in the "Technical data" section ( page 392). Warning! 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 engine temperature is above 194°F (90°C). Allow engine to cool down before removing cap. The coolant reservoir contains hot fluid and is under pressure. 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. 287