kgaddie

My 2016 Mercedes S550 has a slow coolant leak, I have to add maybe a little every 200 miles. I've looked all over for any signs of coolant residue, but the only place I'm seeing is a little in the valley of the intake manifold (maybe a teaspoon worth of coolant, still liquid). Searching around, it looks like the heater valve by the heater core hose can spew but that was on a 2013 model that I saw that video on Youtube. Has that issue happened on the W222 as well?

The coolant reservoir to the side is the one that loses coolant, the one in the middle of the engine stays the same.

Jim Ma

Check the plastic turbo cooling lines. They are known to leak. They are on the font of the engine coming out of the water pump, 2 black plastic lines leading the the drives side turbo.

VII

If you have liquid coolant in the engine that is an active leak that should be easy to diagnose as coolant will quickly evaporate at operating temperature.