mercruiser 4.3L bellows relacement

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kulle

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So I started the journey to replacing my u joint bellows and took the bell housing off. When I removed the exhaust bellows there was this flap thingy in the bellow. Picture linked.attached...anyone know what that is and if that's a major problem?

Additional question(s):

1. I notices there were 2 thin washers when I removed the hinge pins. But only seemed to be on the port side. Should there be 1 for each side or 2 for each side?

2.Can the metal bellows ring be snapped in without a special tool?

Also threw in a pic of the gimble housing area...not sure if it looks good or not ( never owned a boat before )
 

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alldodge

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That is a piece of your exhaust flappers. They are in the exhaust pipe, just below the elbow.
 

poconojoe

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I once found a piece of one way down in my lower drive when I went to change the impeller.
As ALLDODGE stated. The exhaust flappers are just below the elbow....in your engine compartment. They help to prevent water from flowing back into your engine. You don't want water in your engine. Hydrolock is a bad thing. You can do serious damage...bend connecting rods etc.
For example, if you have to come to an abrupt stop, the water can rush the stern and get forced into the exhaust. The flappers stop this. Kind of like a check valve.
Loosen the hose clamps on the rubber couplings to find the flappers. There are many different designs, so make sure you get the correct ones. Hopefully there's a number stamped on your old one.
 

poconojoe

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While you have it all apart, I would change the gimble bearing.
Since you're new at owning a boat and especially one with an I/O, I would suggest changing the impeller. It's in the lower part of the drive and it's what pumps the water toward the engine. Lack of water flow means lack of cooling....bad for a boat engine and it can melt the exhaust flappers.
 

poconojoe

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If you need step by step instructions, get your specific Mercruiser manuals free at this site: boatinfo.no
 

kulle

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Ok, thanks all. I have already inspected and just replaced the impeller and gaskets. I have the manuals for both engine and outdrive, so thank you. So those rubber flappers , do they have a specific name where i can google..im not sure where to look to check which side it came from. Is it the attached? if so, is it right on the exhaust risers?
 

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poconojoe

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Look up mercruiser exhaust flapper. Better yet. If there's a number stamped on the old one, Google that number.
 

achris

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They are called exhaust shutters. That picture is of an exhaust tip, not the same. Have a look through the 'stickies' at the top of the forum. Lots of interesting information you'll find useful...

When posting please include engine and drive serial numbers. You've just called your post "MerCruiser 4.3". Merc have been using the 4.3 since 1985, and it's gone through MANY changes.. even the drive has changed a few times since then.

Chris....
 

poconojoe

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Ok, thanks all. I have already inspected and just replaced the impeller and gaskets. I have the manuals for both engine and outdrive, so thank you. So those rubber flappers , do they have a specific name where i can google..im not sure where to look to check which side it came from. Is it the attached? if so, is it right on the exhaust risers?

I have never seen one that looks like that. They are internal within the exhaust riser. You're lucky to have the old one which helps to ID which new one will fit.
Check both risers to see if both are missing.
Also, as a mention, sometimes they fall down into the bottom of the riser and cause blockage or even corrosion of the riser. So do a good inspection.
 

poconojoe

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They are called exhaust shutters. That picture is of an exhaust tip, not the same. Have a look through the 'stickies' at the top of the forum. Lots of interesting information you'll find useful...

When posting please include engine and drive serial numbers. You've just called your post "MerCruiser 4.3". Merc have been using the 4.3 since 1985, and it's gone through MANY changes.. even the drive has changed a few times since then.

Chris....

Thanks for the correction Chris! Shutters not flappers! I had a brain fart! I'm glad you caught that! I don't want to spread false information.
 

kulle

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Also had these questions...

1. I notices there were 2 thin washers when I removed the hinge pins. But only seemed to be on the port side. Should there be 1 for each side or 2 for each side?

2.Can the metal bellows ring be snapped in without a special tool?

i plan to use slide hammer to remove gimble, but also saw a youtube where someone just tapped the new one into place.

Engine info for water shutter.

Engine serial:0F022537

Engine model: MCM 4.3L | 443B1003S

i found these:
 

kulle

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Yes those are the replacements 807166A3, they just get pushed in, no washers needed
Do a search on the number and can find them cheaper
Good write up here https://forums.iboats.com/forum/eng...-shutters-explained-only-applies-to-4-systems

You can get the ring in without a special tool, but works best with it or can make one out of plywood and 2 hole saws

sorry the washers i referenced were for the bell housing/hinge pin location. when i removed mine i found 2 washers on port side only. is there supposed to be 2 on each sode?
 

kulle

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I Loosen the hose clamps on the rubber couplings to find the flappers. There are many different designs, so make sure you get the correct ones. Hopefully there's a number stamped on your old one.

So on my engine I should be able to access this without needed to remove the enginer ( i read somewhere some models you have to). Would this shutter be blow the exhaust risers?
 

alldodge

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Yes, just remove the boot off the Riser to the elbow and the boot from the elbow to the Y pipe
 

kulle

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Have another issue, screw head broke off, which looks to be some sort of static ground on the bell housing? How F'ed am I?
 

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