This is not a car question but many of you have a similar engine so I am hoping someone may have an answer.

Blueprint 351W based 427. Cruising down the road when coolant starts gushing out. Pull over and coolant is flowing from the drain slot in the water pump mounting plate (the one that actually bolts to the block behind the water pump that the water pump is bolted to.) Tow it home, tear down water pump, and......... nothing! Everything looks fine! We had refilled the coolant (with water) when it was up on the jack stands and confirmed the location of the leak, the rear of the water pump. But when inspected it all looked normal. We had torn the gasket while removing the pump so could not ascertain its original condition. All we could guess was that the gasket had blown out (water flow was pretty substantial) and allowed water to leak into the back of the pump mounting plate and out the drain slot. This was only a theory but there was no other explanation. Cleaned everything up and put it back together. Everything is fine, not a drop of water leaking anywhere.

So, the question is, does anyone have any experience with a water pump gasket just blowing out for no reason? Why would this happen? How can I prevent it from happening again?

Engine did not overheat. Thermostat (180) seemed to be working as we had driven for about 45 minutes prior with no problem. Thermostat works fine now (after the fix). 20 psi pressure cap felt like it was working OK but replaced it just to be safe. I would rather not have this reoccur, but I have no clue why it happened!

If you are not familiar with the water pump I am talking about please do not ask me to explain the assembly. There is a backing plate with bolts that are inaccessible when the pump is mounted. If these are the cause of a leak the pump must be removed to tighten them. And if it leaks in certain positions on the pump, the fluid flows into a chamber behind the pump itself, which is what mine did. As far as I am concerned it is a goofy design, but it is what is on the engine (and thousands of others) so I have to deal with it.

Anyway, thanks for any advice you may be able to give.