What is water bypass port?

[blahthisnamenottaken]

On my 1963 75hp Evinrude, there is a small port on the lower unit that I cannot identify. I have all the manuals, and yet there is no mention of it. The port is on a plate called the "water bypass" plate in the parts manual, so I assume this is my water bypass port (or hole). It is threaded to take a plug, but there is no plug installed.<br /><br />Is this used for flushing the motor? Should it be plugged for normal operation?<br /><br />Behind the plate is basically a small empty cavity with a shaft running through it. I assume the shaft is the water pump shaft, but I'm not terribly sure.

 

[sony2001]

Re: What is water bypass port?

Sounds like its for discharging the lake water from the pump because the engine hasn't reached operating temperature. Then it closes once the temp has been reached or is going higher. Don't plug it!

 

[blahthisnamenottaken]

Re: What is water bypass port?

It's not a valve, it's a threded hole with a missing screw-in plug. Upon closer inspection, the chamer behind it is the same place where fresh water is normally drawn into (from bottom rear) and sucked out (top)<br /><br />??