Subject: Water Pump
Vehicles: All
Condition: Water pump leakage: In individual cases, droplets form at the vent bore hole of the water pump, or traces of coolant evaporation are visible in the engine compartment.
Cause: A fine lubricating film, which must be formed by coolant, is required between the carbon ring and the ceramic ring in the water pump gasket. Leakage caused by this is unimportant and cannot be detected in the compensation tank. In addition, small dirt particles (residue from manufacture) in this area can cause short-term leakage, which is however insignificant. This dirt gets flushed out or remains harmlessly in the "soft" carbon ring.
Remedy: When water pump damage is being evaluated, only a measurable coolant loss from the compensation tank should be considered as decisive, after the entire coolant system (radiator, hoses, connections, compensation tank, etc.) has been checked for leaks. Please note in this context that correct determination of the coolant level is only possible when the engine is cold.
Note: Only water pumps which show a measurable coolant loss can be replaced under warranty.