When I installed my water pump relocation plate I also used silicone sealant on those 2 water pump bolts and nuts too create a seal. When I did my initial break in run I had no leaks but if leaks do occur at some point I am going to try these sealing washers from McMaster Carr. The rubber compound is Buna N which is good for 220 degrees F. The washers are rated up to 2000psi. The rubber is bonded to the zinc plated steel washer. Ideally it would be nice if the washer was stainless. They come in all standard inch sizes.
