Water Pump - Replacement Justification

REF. NO. 20/43

TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: NOVEMBER 1989

SUBJECT:
1. COOLANT RESIDUE AT THE PUMP
2. ANTICORROSION/ANTIFREEZE

1. Coolant Residue at the Pump

Traces of coolant residue and wetness (formation of droplets) at the vent hole of the coolant pump are not considered "leakage". Pump replacements under such conditions are not justified.

A small amount of coolant in the groove of the pump seal is required for lubrication of the pump. Coolant droplets forming at the vent hole dry up and leave a distinct residue due to the high content of solid matter in the coolant (6g/100cc). This is particularly obvious on vehicles used for short distance driving with the engine being started and stopped frequently.

Replace a coolant pump only if it is clearly visible that coolant drips continuously from the vent hole.

Water pumps returned for leaking coolant will be checked very carefully and warranty claims might be rejected if a pump is found to be in acceptable working order.

2. Anticorrosion/Antifreeze

We recommend the use of MB anticorrosion/antifreeze Q 1 03 0001. This coolant protects all light-alloy components in the cooling system from corrosion. It also offers protection against engine boil-over at high outside temperatures, as well as freeze protection. The coolant should always be in the cooling system at the proper ratio.

Any other brand of antifreeze used must meet Mercedes-Benz specifications.

If coolant specifications as per sheet 310 (Microfiche Specifications for Service Products Z7 0550 03 1) are not observed, corrosion might occur in the cooling system. As a result of corrosion, deposits may clog ducts in the radiator and heat exchanger, leading to engine damage.