An idea for preventing water pump impeller damage to heads
 

When WP impellers break apart, they can send plastic bits into the narrow water passages in the head where they block water flow and can cause cracked heads from localised overheating.

So I was thinking, what about a WP gasket that is essentially a mesh screen which covers the outflow section of the water pump? The, if the impeller breaks, the bits stay in the water pump and can't circulate through the motor? Sure, the bits will chew up the impeller more quickly, but at least you prevent plastic bits going into the motor.

Should I start working on the patent?

Great idea if does not present a significant flow impedance or present another mode of failure.

It has been done before in hydraulic systems and large heat transport systems so you want to research the patents there....many times a specialized, application, specific slant will make you unique and won't necessarily mean an infringement.

Go forth and invent!

As far as blocking flow goes, if the mesh is say 1/4 the diameter of the coolant passages, then it should block debris without significant effect on flow. I guess the mesh would have to be fairly strong, I could see all the plastic impeller parts being stirred up might rip the mesh, sending pieces of mesh into the motor.

This already exists. If you do a patent search, you'll find it.