General notes on the installation of water pumps and the use of sealants or grease

Design of a water pump:

1. Hub or flange onto which the belt pulley for driving the pump is fitted

2. Cover for the collecting tank with suitable drainage hole

3. Seat for one of the bolts attaching the pump to the engine

4. Tank for possible leakages from the mechanical shaft seal

5. Sealing ring (O-ring) on the pump’s mounting surface

6. Mechanical shaft seal (slide ring or axial seal)

7. Impeller (in a closed version in this case)

8. Pump housing

9. Integral bearing


Loss of coolant via the sealing/contact surface or the drainage hole/collecting tank, plus a noise when running


Improper and/or excessive use of sealant or grease. This leads to leaks and/or noise when running. The foreign agent is pulled into the mechanical shaft seal by suction, which could cause failure of the seal.


If a water pump is fitted with a rubber sealing ring or a dry seal (e.g. a paper seal), only these seals may be used. A sealant only needs to be used in the absence of a corresponding seal. Such water pumps generally have grooves for applying the sealant in the sealing/contact surface. If a sealant is required, only the correct sealant as specified by the vehicle manufacturer should be used. You must also take care to follow the instructions of the sealant manufacturer (drying time, etc.). When mounting the pump, wet the rubber O-ring with the coolant for the vehicle. Grease, sealants or other such agents may not be used!

If a sealant is required, no other seal must be used. Make sure that the sealant is applied correctly. As in the example here, only fill the groove with a bead measuring 3-4mm in width.

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Published on: October 15, 2022

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