Piece fell out when separating upper and lower housing

[newboatguy18]

Hello,

I'm working on a Mercruiser Alpha One Gen 2, and I was separating the upper and lower housing for an impeller change when a piece fell out. I attached a picture of it. I can't figure out where it came from. Can anyone tell me what this is, where it goes, and what it means?

From some of my research, it looks like it might be a flapper valve? If it is, is it a necessity for me to replace it?

Thank you!

 

[GA_Boater]

Welcome to your flapper ID specialists. LOL

Yep, it is your flapper and it helps prevent water surging up the exhaust and damaging your motor. It fits in the exhaust Y pipe or elbow depending on what motor you have. What motor do you have? Inlines have 1 and V motors have 2 flappers.

Should you replace it - It's up to you. I would.

 

[harringtondav]

I second GA_Boater These are downstream from your exhaust risers. Depending on your engine and vintage, maybe in the elbows, maybe in the Y pipe. Kinda a pain removing all of those hose clamps and forcing off the boots, but you'll wish you did if you quench your hot exhaust valves with a big backwash wave.

If you don't replace it, always remember to come off a plane slowly and keep your throttle somewhat open until that back rush dies. A lot to remember, so you might want to fix it.

 

[fishrdan]

Fix it.... I hydro-locked my engine once when the ignition switch went on the fritz, while running on plane.

Engine shut off, then the stern wake caught up the the boat, swamping the exhaust, and filling cylinders.

Click/cClunk, Click/Clunk, Click/Clunk, engine wouldn't turn over. Pulled plugs and water shot out of cylinders....

 

[tacx]

Are these flappers something that needs to be inspected now and then? If so is it a big job?

 

[Alumarine]

I'm not sure if the pictures you posted are of both sides of the same piece or 2 separate pieces.
A whole flapper consists of 2 parts like that joined together.
If you only have the 1 half, then you must find and remove the other half.

 

[newboatguy18]

Thank you everyone -- it is one piece, so the other piece must be in there somewhere. Does anyone have a link to a video or a website showing how to replace these on a mercruiser 3.0L?

 

[harringtondav]

I just checked the 3.0L exhaust system parts diagram. It looks like a double flapper at the top of the transom exhaust elbow, right under the connector hose. Loosen the four hose clamps on the hose, You'll probably need a screw driver to unstick it from both elbows, and maybe a heat gun/hair driver to lightly soften it up so yo can get it off.

You may be able to push it up or down far enough to see the top of the lower exhaust elbow and the remaining half. It's held in place by two hinge grommets that lift up out of a cast slot. Merc flapper 60930, $32, Sierra 181-2727, $23. Grommet 25-4309, 90 cents ea.

 

[newboatguy18]

Thank you. For other people's reference, it looks like you mean Grommet 25-43809. If I take it apart, is there anything special I need to do to re-seal it?

 

[GA_Boater]

No - The elbow hose shouldn't leak after clamping with the hose clamps.

Just be careful not to tear the hose, it may not be as soft as when it was new.

Once you get the hose off, you will see if the rest of the flapper is still there. If not, you may have to go fishing.

Has the boat had any overheating problems? Often lack of cooling water through the exhaust melts the flappers.

 

[newboatguy18]

Yes -- that was what set me onto this in the first place -- I noticed that it was overheating. I took the outdrive apart because I thought it might be an issue with the impeller. I've had the boat for a few years, and haven't ever changed it.

 

[newboatguy18]

It looks like a double flapper at the top of the transom exhaust elbow, right under the connector hose.

Assuming I have no idea where the transom exhaust elbow is, do you by any chance have a diagram to show me where it is?

Thanks.

 

[Alumarine]

Here's a link to a manual for 1998 or newer 3.0 motors.
I'm not sure what year your's is.

http://boatinfo.no/lib/mercruiser/manuals/mercruiser26.html#/398

 

[newboatguy18]

Thank you, Marc!

 

[newboatguy18]

The manual says to loosen exhaust bellows clamps, remove hose clamps, and "remove intermediate exhaust pipe", in that order.

I did the first two -- but now the intermediate exhaust pipe won't budge. The hoses / seals around it will rotate, but I don't see a way to slide them up or lower them. Am I missing something?

 

[Rick Stephens]

I'm not a big fan of trying to slide rubber exhaust up down or whatever to get to the shutters. IMHO, the easiest way is to purchase a replacement elbow to manifold gasket (only use the metalized OEM ones!) and then pull the elbow and lift that intermediate pipe, rubber connector and all, off the lower exhaust pipe. It's worth the $$ to do it the easy way.