Hole in yanmar 1GM10 near water pump

[antoine pare]

I have found a hole next to my water pump mount in the body of my Yanmar 1GM10.

It goes into the chamber where the shaft of the water pump connects to the rotary part of the engine to get the water pump to run.
This chamber is usually full of oil and when my engine runs I see quite a lot of oil coming out of the hole.

I have a feeling this hole had been filled in the past but I have recently wire brushed the engine to give it a good clean and I have potentially removed the previous fix.

I was thinking of using some of these paste that harden and can withstand high temperature.
Any other ideas?

Any idea what type of metal is used in the Yanmar 1GM10 at that specific location?

 

[Tranona]

That is the front cover and as you say is full of oil. It is an aluminium casting and unfortunately the clever designers decided to put a mixture of metals through it to drive the pump - mild steel bolts, bronze housing and seals that leak water. So common to get corrosion of the aluminium around the water pump. I use an aluminium loaded epoxy filler to repair mine (scrounged from the tank maintenance workshop at Bovington) I had mine in pieces so it was perfectly clean and the filler adhered well, although there were no actual holes.