Why the little hole in the waterpump?

[O/B Dude]

Why is that hole there in the front left of the waterpump base? Looks like a drain hole and boy does it drain. Tinkering around with my gear case, I put a garden hose on to the copper tube that transfers water from the pump to the exhaust divider. Put the other end of the tube into the top of the pump. Turned on the water to check for leaks in the seals and pump. Water shot out the little drain hole at the left front. Whats the purpose of this hole? Seems to me it would rob the motor of volume.

Anyone know fer sure?

OBD

[MTCM]

Yep that's a Bypass and Drain Hole. Allows the water to drain out so the pump housing won't crack/break during storage in freezing weather/conditions.

[Jay R.]

If It's what i think your talking about it also helps get the pump primed.

[O/B Dude]

OK, those answers make sense. thanks guys.