Possible y pipe leak

nextboat1

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Mar 17, 2013
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Mercruiser alpha gen II. Upon inspecting a boat that I just purchased I found a small piece of rubber gasket in one of the exhaust holes in the outer transom plate. I think that it might be part of the y pipe gasket that has worked its way to where I found it, but I'm not sure. I have ran the boat on miffs but have not seen any leaks. Is there any further checks that I can do? Could that piece of rubber be from something else?
 

Fishermark

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Re: Possible y pipe leak

Probably the remains of an exhaust shutter.
 

81 Checkmate

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Re: Possible y pipe leak

Also if it was the Y-pipe....it would be leaking water inside the bilge!
 

nextboat1

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Re: Possible y pipe leak

I haven't had it in the water yet so I can't say if water would leak into the Bilge not. I do not see any water leaking when the boat is running on muffs. The piece is very thin and almost like rubber o ring, so I don't believe that it is the impeller.
 

81 Checkmate

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Re: Possible y pipe leak

The piece is very thin and almost like rubber o ring, so I don't believe that it is the impeller.

Do you know when the last time the impeller has been replaced?... If not that would be the first place id look..........If thats good next would be the shutter's (Flapper's as some people refer) in the Y-Pipe.

If it was the Y-Pipe O rings it would leak water inside while running on muffs........FYI - there are 3 O-Rings on the Y-Pipe that fit in a groove with flats on each side of the groove.........If it tore or frayed it would have a hard time getting in the exhaust path.
 

Fishermark

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Re: Possible y pipe leak

Well, it wouldn't be the impeller - there is no way the impeller pieces could end up in the exhaust passage. I do agree however that you ought to replace the impeller before going out on the water since you don't know when it was last replaced.
 

nextboat1

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Re: Possible y pipe leak

The impeller definitely on the top of my list to get changed. Ill try to get a picture of the mystery piece tonight and post it. Thanks guys!
 

nextboat1

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Re: Possible y pipe leak

Here is a picture of the piece of rubber that I pulled out of the exhaust port in the outer transom plate on the starboard side. The picture isn't the best but at least it will give an idea of size. The rubber is kind of rounded but flat on one side. Could this be a piece from and exhaust flapper?
 

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81 Checkmate

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Re: Possible y pipe leak

Now we know what it looks like.......Looks like the edge of rubber flapper skin to me.

Fishermark.......A peice of the impeller could get into the exhaust passage.....It would have to go thru the block water passage then into the manifold/riser...then in the exhaust. It's posible
 

nextboat1

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Re: Possible y pipe leak

That's what I was hoping for. I'm going to try to pull the risers this weekend and see if I can fish out the remaining pieces. Thanks.
 

Volphin

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Re: Possible y pipe leak

That's no impeller shred. It IS an exhaust shutter seal. Replace the shutters with the new design. This winter. Go boating for now. No need to pull manis off yet.
 

nextboat1

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Re: Possible y pipe leak

Sounds great guys! Thank you for all of your help!
 
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