OMC exhaust flapper alternative.

[subcrx]

power specs, Originally OMC cobra 5.7. Sei 106 outdrive conversion. Has OMC log risers with Y pipe.
The boat has been missing the flappers in the Y pipe since I've owned it. I've had water intrusion on 3 separate occasions. 1st and 2nd time waiting in line to get into the launch ramp trying to simply hold my spot in the water forward and reversing. Water hydrolocked the engine, the third time I slightly overheated it and water got in and hydrolocked again. My guess is if I had flappers it would have stopped the water intrusion. I've tried three different types of flappers, none of them fit. I must have some rare Y pipe, nothing seems to fit it.

Is there anything else I can use instead of the factory flapper? Would a 3 inch flapper work on the exhaust port on the transom? I've attached a picture of my Y pipe.

 

[Renken2000Classic]

I've got a 3" rubber pvc cap, strategically cut, on my 4.3L and it's worked fine for a coupla seasons. But it's got a remnant of the exhaust bellows underneath it or it would be a little too big. As it is, it fits perfect and is attached with a hose clamp.

When I say strategically cut, I mean I sawed it to where it's hinged at the top, like between 11 and 1, something like that.

My inner flappers are gone too.

 

[Scott Danforth]

Could ditch the log manifolds

 

[subcrx]

Could ditch the log manifolds

Then I wouldn't know where to put my heat exchanger.

 

[subcrx]

I've got a 3" rubber pvc cap, strategically cut, on my 4.3L and it's worked fine for a coupla seasons. But it's got a remnant of the exhaust bellows underneath it or it would be a little too big. As it is, it fits perfect and is attached with a hose clamp.

When I say strategically cut, I mean I sawed it to where it's hinged at the top, like between 11 and 1, something like that.

My inner flappers are gone too.

I'm having a hard time picturing what you did.

 

[Renken2000Classic]

Put a homemade flapper on the exhaust hole that comes out the back, where the exhaust bellows would normally go. I believe I read on here that some boats have that as part of their design (Volvo Penta?).

Since I couldn't just cap it off with what I used (lol), I cut it so it would come open under exhaust pressure, but tend to close if a following swell hits you or whatever (cap left connected at the top).

I had an overheat on one side due to old original exh manifolds. I was worried about junk (like maybe the old flappers) being stuck in there and so cut the exhaust bellows (it was fairly new too) to examine the Y-pipe and drive as best I could with a remote camera.

I was able to put the new "flapper" on by just moving the drive to the left.

I'm not recommending it per se, like I don't know if that works in all situations, but has worked for me. My brother chopped the throttle good one time with it on there, with no repercussions that I could tell.

 

[kenny nunez]

Crowley marine has in stock what you may be able to use.
0911872. Bushing. Qty4
0984467. Flapper. Qty2
0911873. Pin. Qty2
These show with the style rear riser like in the picture you posted.

 

[subcrx]

Crowley marine has in stock what you may be able to use.
0911872. Bushing. Qty4
0984467. Flapper. Qty2
0911873. Pin. Qty2
These show with the style rear riser like in the picture you posted.

I've tried 3 different Y pipe flappers. None of them fit.

 

[subcrx]

What if I stick one of these on the back of the boat where the exhaust bellow goes. Renken you said home made. I've never seen these below the water line. Guess I'd just have to try it out and see how it behaves when I'm stopped.

 

[kenny nunez]

Were they OMC parts? The only other thing I can think of center rise manifolds with extensions. Not cheap but should solve the problem.

 

[subcrx]

Were they OMC parts? The only other thing I can think of center rise manifolds with extensions. Not cheap but should solve the problem.

They were omc yes. Tried two different types. Nothing fits. I want to do center risers but not sure how to make the conversion. Like what elbows I need and all that.

 

[kenny nunez]

Just google Barr manifolds. They do have riser extensions but only for Mercruiser style rear riser. The exhaust hoses are easy to adapt.

 

[subcrx]

I got this flapper to fit on the transom exhaust port. Taking it out tomorrow. Think it will work?

 

[subcrx]

Got it out this weekend. Two days on the water not one issue. Thanks guys