Continental has issued some useful general advice on the installation of water pumps and in particular the use of sealants or grease. 

When a replacement pump is fitted great care must be taken with the sealing to the contact surface. Lack of care can result in a loss of coolant via the sealing/contact surface or the drainage hole/collecting tank. The pump may also make excessive noise when running. 

The cause of this is generally the improper and/or excessive use of sealant or grease. This leads to leaks and noise when running. Contaminants are also pulled into the mechanical shaft seal by suction, which can mean failure of the seal.

Continental advises that 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. Technicians must also take care to follow the instructions of the sealant manufacturer such as drying time. If a sealant is required, no other seal must be used. The technician also needs to makes sure the sealant is applied correctly, only filling the groove with a bead measuring 3-4mm in width. 

Were a seal is provided, when mounting the pump, the technician should wet the rubber O-ring with the coolant for the vehicle. Grease, sealants or other such agents may not be used. 

You can download the Continental technical bulletin (No.66) and other useful tips here.