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Exhaust flapper

M

milford65

Member
"I just replaced my gimble sea

"I just replaced my gimble seal,bearing,all bellows,water hose,trim switchs and started on water pump...

I looked in upper half of out drive and there was a exhaust flapper just laying there...

It looks worn out but my real question is where the heck does it go........

I can see it goes on hinge pin..


I heard from other boaters that it is not needed..

I would still like to know where it goes my manuals are not showing me any discriptions..

I am thinking it belongs back at exhaust manifold or Y pipe...........

I have to wash the grease out hair now always wipe your hands before scratching your head

LOL Bill"
 
"Bill,
I got the flapper when

"Bill,
I got the flapper when I was on shore leave in the BVI. Just kidding. I heard something like that in a movie.

The flappers , a.k.a. Exhaust Water Shutters, are located in the exhaust y-pipe. The flappers help prevent water from running back into the engine.
As they age they can make noise like a "clack clack clack". They eventually break loose and get stuck down in the exhaust Y-pipe or in the exhaust passage (like in your case??).

I've read that to change them in an older 3-piece exhaust y-pipe setup, the engine will have to be removed. (Don't quote me on that though!)
Boats with newer y-pipe setups have the shutters located at the top of the pipe and doesn't require the engine to be removed to replace em but you do have to remove the exhaust elbow from the manifold.

Can you run your boat without them? Sure but there would be a very real chance water can enter your exhaust system.

Hope this helps!
Ed"
 
"Guy, I went to the link but c

"Guy, I went to the link but could not see a flapper for my motor; 1979 470 2 bbl carb. Does it have a flapper? Tnx, JW in Dixie"
 
"Yea,
That was not a very cle

"Yea,
That was not a very clear sight.

I have found 3 part #s though

18-2732 replaces 807166A3..water shutter
18-2733 replaces 99370A2..water shutter
18-2727 replaces0930..exhaust water shutter

I think I am going to take the big elbow off and look.
If it goes there great if not I have a kicker motor....

selco manual "All V8 models you have pull the motor to service the shutter""
 
"Thanks, Guy. Guess I was look

"Thanks, Guy. Guess I was looking for the word "flapper", and didn't notice shutter. So, I guess I have one, unless the previous owner removed it. Hope not. What is it made of anyway?"
 
Warren:

I use that site all

Warren:

I use that site all the time for reference and part numbers only; their parts are expensive.
I thought shutters are metal w/a rubber edge to seal out backwash. Clean any carbon build up out of the exhaust where the flapper makes contact.
 
"Hey guys, I am replacing the

"Hey guys, I am replacing the exhaust flapper on my 89 3.0 mercruiser and I have a stupid question, but I want to get it correct. There is metal on 1 side of the flapper, and I just wanted to know which way the metal side should face? The flapper seems to move freely with it either facing up or down. Any help is much appreciated. Thanks."
 
"Rubber side up, so that when

"Rubber side up, so that when installed the rubber on the lips presses against the sides of the downpipe.
The whole assembly sits in the pipe like an inverted V on the swivel rod, that sits in the notches in the pipe.

Rod"
 
Yes it is needed.Reversing and

Yes it is needed.Reversing and then shutting the engines off to anchor in shalow water or similar situation can let water into the cylinders causing hydro lock.Need to pull plugs at that point....Todd
 
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