Notes on coolant level - AH20.00-P-1142-01GZB
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2011 Mercedes-Benz ML350, 2010 Mercedes-Benz ML350, 2009 Mercedes-Benz ML320, 2009 Mercedes-Benz GL320, and 2008 Mercedes-Benz ML320. However, it is still accessible from the selected car via links, so may be relevant.
The coolant level must, on a cold engine, reach up to the marking (arrow) in the coolant expansion reservoir.
When the coolant is warm the coolant level in the coolant expansion reservoir is about 1 cm above the marking (arrow).