Round Water Passage Holes At Base Of Powerhead

[boatmon345]

Rebuilding 1997 Yamaha 150HP 2 stroke Saltwater Series II S150TXRV powerhead.<br />( Click here to view updated blog with new pictures )<br /><br />At the base of the powerhead there are 2 circular water passage holes that match up with round holes on the midsection.<br /> <br /><br />In preparing the midsection surface for installation of the powerhead, I found that these round holes are about an inch and a half deep, but don't go anywhere; they appear closed.<br />Click here for picture of midsection <br /><br />Can this be right? If so, how does water drain from the cylinder water jackets?

 

[WillyBWright]

Re: Round Water Passage Holes At Base Of Powerhead

They're just exhaust relief holes for when the motor is running slow. As an added benefit, some water that has mixed with the exhaust sprays out there to show that the powerhead is getting water. It's not a direct exit for the cooling system. I imagine it is ducted in the midsection casting.

 

[boatmon345]

Re: Round Water Passage Holes At Base Of Powerhead

Willy, I think (not sure) you are referring to the 2 square holes on the mid section that I have seen exhaust and water spitting from before.<br /><br />What I am referring to is different. There are two round holes that the bottom of the powerhead that match up to on the mating surface of the midsection (where the power head mounts). If you click the picture link on my previous post, and notice the red circles I have placed on the picture, these are the holes I am referring to. <br /><br />These holes on the midsection seem closed. UNLESS they are so full of corrosion that they only APPEAR closed. But before I start digigng and poking in those holes on the midsection in an effort to find an opening, I was hoping someone could tell me if they are supposed to be closed or open.

 

[boatmon345]

Re: Round Water Passage Holes At Base Of Powerhead

nevermind, too late now, i dont want to konw, lol