two ports on the exterior transom plate, bravo II

[demaris]

well i have returned to the boat to try and find out why it tried to sink on me.
twin 7.4l mercruiser bravo II outdrives.
last april the port engine/outdrive developed a major leak that eventually forced me to truck my 35ft thundercraft to the storage yard.

viewed from the inside between the two engines, in the end i could see a curtain of water sliding down the inside face of the transom under the motor.
long story short, plugged the exhaust bellows, put it in the water. still leaking. mechanic knew of two ports on the bottom of the outside transom plate of the outdrive. they are about an inch and 3/8ths in diameter, one on either side of the bottom. plugged these, back in the water no leak.
what i need to know is where or what do these ports go to. outdrive is off, exhaust bellows is removed. engine still in place with little room to see anything. cannot see where the two ports would enter the wye tube and be related to exhaust ducting.

original theory was that the top of the wye tube was corroded through from a leak but now not so sure.

?
any help?

thanks

stephen

 

[Bt Doctur]

If you had plugged the exaust below and still had the leak and when the reliefs were plugged the leak stopped you would have a corroded Y pipe

 

[alldodge]

^^^ Agree

 

[demaris]

that's what i originally thought and have a replacement in the van already. but i can't see where the ports enter the exhaust system. i have to pull the engine to get to ANYTHING [FONT=arial, helvetica, sans-serif]so i suspect that everything will become obvious. was just checking on whether i had some sys that i was unaware of. thanks for the reply
stephen[/FONT]

 

[Bondo]

but i can't see where the ports enter the exhaust system.

Ayuh,..... It happens internally, inside the transom assembly,.....

 

[GA_Boater]

The idle relief ports are to relieve exhaust back pressure at idle. That's why they spit water and exhaust, so naturally they are part of the exhaust.

Stick a cell phone with a camera down there when the water is pouring in and you should be able to see the holed Y pipe. Just don't soak the phone.

 

[Bt Doctur]

similiar to yours, the oblong ports are the exaust reliefs
click to enlarge

 

[Scott Danforth]

it the y-pipe is corroded, it would be at the bottom. also, sometimes the flappers drop and the pins wear thru the y-pipe

 

[demaris]

similiar to yours, the oblong ports are the exaust reliefs
click to enlarge

u must be talking about those above the main wye tube entrance, not the ones with the arrow.

 

[GA_Boater]

Are the arrows pointing to oblong ports? No. It's just a convenient pic BT had.

 

[alldodge]

Exhaust ports

 

[demaris]

got it. closing in on getting the engine out of the way. will know soon enough what went wrong.

 

[Bt Doctur]

Thanks AD , edit feature was off line