Exhaust shutter question

[Spiderhole]

Good afternoon, I have a question about a new (86' 4Winn's) boat that I just came into. I am fairly familiar with the 4.3L Mercruiser motor and alpha one outdrive. This has the Gen I Alpha One. Before I drop it into the water I decided to do a full maintenance on the boat and inspect as much as I can. I decided to replace the exhaust manifolds and risers as it still had the original. It has exhaust shutters that are different the the ones I've seen in other Y pipes, and I was hoping you guys could tell me if what I am looking at is correct. The other ones I had were literally like two spring loaded flaps. These seem to just sit on a rod that goes through them and just kind of hang there. I found the replacements online and they look identical. Is this correct? Also, one of the boots had a small rip that only goes as far as the first tie down - I don't think it will leak if I clamp the two of them down, but I wanted to see if it is even possible to get a replacement boot?

 

[alldodge]

Its in the Adults only and put together by achris
http://forums.iboats.com/forum/engi...rcruiser-v6-v8-i-o-exhaust-shutters-explained

 

[Scott Danforth]

I would replace both the flappers and the rubber hoses. that crack will simply migrate

see the link that AD posted

 

[Spiderhole]

I've seen that sticky post and it was helpful for the last set I replaced it was helpful, but to be honest, I'm still somewhat confused as it relates to the ones I am looking at now... this shutter I am looking at now is the old style metal one that was stamped with 99370. It literally looks like they just hang there in place. It looks like it's saying I should replace with 807166A3? It doesn't look like it would fit in my setup if that's the case.

 

[alldodge]

Always helps with a serial number

In 1986 there can be 3 inch exhaust 99370A2
http://www.mercruiserparts.com/bam/subassembly/31472/919/220

And 4 inch exhaust 807166A3
http://www.mercruiserparts.com/bam/subassembly/31472/919/230

Chris may need to update his exhaust sticky unless I'm missing something. If you have the 3 inch exhaust then you need 99370A2

 

[Spiderhole]

Always helps with a serial number

In 1986 there can be 3 inch exhaust 99370A2
http://www.mercruiserparts.com/bam/subassembly/31472/919/220

And 4 inch exhaust 807166A3
http://www.mercruiserparts.com/bam/subassembly/31472/919/230

Chris may need to update his exhaust sticky unless I'm missing something. If you have the 3 inch exhaust then you need 99370A2

I believe mine is the 3 inch, thank you for your post with the diagram. With this type of flapper, what I really am trying to understand is if I need to replace what I have in place already. I included some picture on my original post that show how they sit in the pipe - to me, they look like that's how they were designed, but I don't know. I don't want to replace parts if I don't need to. I don't see anything that looks like water has gotten in there. I am just not familiar enough with this type to know if they are supposed to seal all the way across the pipe, because I don't see how it would do it if that was the case.

 

[nateo]

The rubber on the edge is what wears out. If you dont replace those boat will still run but you'll hear metal on metal knocking sound. Much quiter with new rubber.

 

[alldodge]

^ Agree, look real close at them, look for hair line crack

 

[Spiderhole]

They look solid, just a bit of the front of the rubber is gone.

Can anyone tell me... is the way they are sitting in the tubes in the pictures I posted correct??? The main thing I want to make sure is that what I am looking at is normal.

 

[alldodge]

Yes, this is correct. The larger end is down, if water rushes up it closes

 

[Spiderhole]

Yes, this is correct. The larger end is down, if water rushes up it closes

OK, perfect, thank you for the info

 

[achris]

...Chris may need to update his exhaust sticky unless I'm missing something. If you have the 3 inch exhaust then you need 99370A2

Done.