4.3 Exhaust Flappers - which are the right ones?

[samm835]

I have a 1995 or 96 Mercruiser with a 4.3LX alphaone. The # is 0K023103, how do I know which flappers will fit? The local marine shop said to use 807166A3. If I remember correctly these look a little different that the ones on now. How does the motor # help?

**Never mind....I didn't have the serial # when I went to the shop.....only year and make, so this is what they were showing. I called back with # and they let me know that with a two piece (which I have) I needed 807166A1, which of course are more expensive lol SUCKS

 

[achris]

Re: 4.3 Exhaust Flappers - which are the right ones?

If the 2 piece manifold/elbow was factory installed and not a mod from an original 1 piece set-up, then yes, the ---A1 number is the correct one. The ---A3 number is for conversion from the old single piece flapper (about mid-95 and earlier)...

 

[samm835]

Re: 4.3 Exhaust Flappers - which are the right ones?

Well ok now you have me totally confused....ha thanks. Ok so this boat is fairly new to me. So how do I know which ones I have? i do know I have two rubber boots on both sides. They look oval almost, is there a way to know for sure? I will say, the new ones I got look almost identical to what I pulled out.

 

[achris]

Re: 4.3 Exhaust Flappers - which are the right ones?

ok.. Here's the deal.

The early shutters (from about 1986 to 1995) were a single flap with a rod through them (part # -14348A1, 'Old style' in the picture below). Problems appeared with the shutter hinge points wearing the rod through and the shutter falling down and either disappearing out the prop with the exhaust, or getting stuck in the bottom of the Y-pipe and vibrating and wearing a hole through the pipe, causing lots of water to enter the boat quite quickly ...

The solution was to redesign the pipe and create a new shutter, the dual flap one you see these days. But (and there's always a 'but' with Merc :facepalm they designed two different new Y-pipes, one for the V6 one piece manifolds (#-807130A7) and one for the 2 piece manifold (#-807130A4, used on both V6 and V8s)...

So, we have 2 new numbers.. (both look similar to the 'New style' in the picture below, but they are NOT interchangeable)

Shutters for use on One piece manifold Y-pipe (only ever used on V6s, from about 1996 to 1999) -807166A2
Shutters for use on Two piece exhaust Y-pipe (V6/V8s) -807166A1

Now, here comes the tricky bit. Merc realised the original (-14348A1) shutters were a problem, and created a retro-fit kit to enable the new style shutters to be fitted to the old style Y-pipe (#-44266T1), they have the number -807166A3.

Now here's the really nasty, bite in the bum bit, if you have a V6. Most V6s that came out with the single piece manifold have been converted to 2 piece (a wise move if you'd like to keep your engine)... But, you still need to use the shutters that fit in the Y-pipe that are for the single piece manifold, unless (and this is usually unlikely) the Y-pipe was changed with the manifolds... But that would mean removing the engine, which most people wouldn't do... So, see if you can find a history of the engine, or maybe a casting number on the Y-pipe. You may have a 2 piece manifold Y-pipe, in which case you'd need the A1 number, or you have a 2 piece retrofit on a one piece manifold Y-pipe, in which case you need the A2 shutter

Hope this helps with the confusion (one way or the other )

Chris.....

 

[samm835]

Re: 4.3 Exhaust Flappers - which are the right ones?

Well it makes a bit more sense.....I guess another way of telling what I have is pull the two boots off and see whats left. Here is what was in my drive when I pulled it off to change the impeller. Which just by looks, look like the new style, not the retro fit or the old style.

 

[achris]

Re: 4.3 Exhaust Flappers - which are the right ones?

New style yes, but which new style? (remember, there are effectively 3 different 'new styles')

 

[samm835]

Re: 4.3 Exhaust Flappers - which are the right ones?

You gotta love when there are so many changes to a motor. So without knowing the serial#'s the next best way to identify what I have is to actually take the boot off and pull out what is currently there and replace with the exact same design correct? Thanks for working with me on this, it seemed fairly easy at first (HA).