Mercedes-Benz W212 coolant leak
220 CDIE220 CDI300 CDI350 CDI
Where does coolant usually leak from on a W212 CDI?
Typical leak points are the fuel filter housing and the water pump. On the OM651 the filter housing sits between the thermostat and the cover, and its inner support can break. The plastic flange on the left side of the cover can also leak. The repair is usually a new part.
How is a coolant leak found?
The leak is often found with a pressure test, done through the expansion tank cap at about 1.5 bar. The leak points are checked visually, especially the water pump and the filter housing.
How can a water pump leak be recognised?
A sign can be coolant on top of the serpentine belt. Replacing the water pump requires removing the belt and the air intake pipe and draining the coolant, so the job is best left to a workshop.
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