EFI water pump question

Hi all, in the process of checking the condition of the timing belt on my 1.3 EFI I also checked the condition of the water pump - turns out it's O.K. but I noticed a small hole 2 or 3 mms diam in the casting going into the shaft casing. Does anyone know if this is for lubrication? and if so, what would be the best lube. as the water pump needs all the help it can get in a Hijet.

Paul.

turns out there are two holes, a vent (on top) to stop heat/pressure build-up and a weep hole (bottom) to allow any water that gets through the seals to escape.