Andreas.

Good evening guys i have a mercedes e class w213 with the 2L 654 engine the car is leaking coolant but cant find where it is.firts of all ive found some cooland marks along the exhaust manifold taking the shape of the exhaust manifold flange found markings along the thermostat taking its shape as well and ive come to the conclusion that the car somehow makes alot of pressure and cause the coolant to expand whenever is possible ive changed the thermostat thinking it was stuck and causing alot of pressure no luck there ive changed water pump aswell and tried a coolant cap also. Ive put pressure to see where the car will leak ive put 1.5bar of pressure left it for hours and never leaked.Did anyone come ac this problem and what was it?

aks_19_ak

Although you mentioned you've changed your water pump already; these were just posted for OM651 engined Vitos by a mechanic I've been to here in Oz. Probably not going to help you much if you've got a new pump altogether, but pasting for future reference