exhaust flappers

chilltech

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Hi guys, new member here. I bought a 2000 Stingray LX at the end of last summer and I'm getting familiar with this boat. I've never owned a boat with an I/O before. It's got a merc 4.3L vortec with the one piece exhaust manifolds. Whats the proper position of the exhaust flappers at rest? I took my exhaust manifolds off for inspection and see that the flappers look to be in good shape but are not closed, is this normal? Is it just the back flow of water that will push them closed, or does the fact that they are open now indicate that they should be replaced? Thanks' for all input.
 

Bondo

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Re: exhaust flappers

Hi guys, new member here. I bought a 2000 Stingray LX at the end of last summer and I'm getting familiar with this boat. I've never owned a boat with an I/O before. It's got a merc 4.3L vortec with the one piece exhaust manifolds. Whats the proper position of the exhaust flappers at rest? I took my exhaust manifolds off for inspection and see that the flappers look to be in good shape but are not closed, is this normal? Is it just the back flow of water that will push them closed, or does the fact that they are open now indicate that they should be replaced? Thanks' for all input.

Ayuh,.... Welcome Aboard,.... Post a picture of yer shutters,... I'm guessin' they're fine,...

The 1 piece manifolds are what ya oughta be Replacin' with a 2 piece manifold/ riser set,...

The 1 piece manifolds are Known to suffer from core shift, 'n have ruined many a motor, even though they inspect, 'n test Ok,..
 

chilltech

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Re: exhaust flappers

Thanks' Bondo,
I will try to post some pics tomorrow night. I did test the exhaust manifolds because when I took em off there was a rust drip/puddle stain in the bottom of exhaust manifold port from cyl#6 that raised an eyebrow. As you said it appears to be ok. I tested it on an engine stand and pumped water through it for a few hours, then flipped it upside down and filled it till I could see the water rising up in the outlet of the jacket thinking the leak may be in the upper cast part of the elbow. I let it sit for days expecting to get some wetness in the exhaust side but it's dry as a bone. As far as I know this boat was only used in fresh water. I pulled em off as a formality based on what I have read on this forum expecting to just stick em back on, now I'm not so sure. I really didn't want to spend 1200.$$ to change em out if it didn't really need it. What's the likely hood that the rust puddle was formed from condensate? It sounds like I'll have to bite the bullet and change em just to be safe.
 

chilltech

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Re: exhaust flappers

boat exhaust 004.jpgboat exhaust 005.jpg
Bondo,
So I've attempted to attach a couple pictures of my water shutters. Hopefully they load, let me know what you think.

Thanks'
 

Bondo

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Re: exhaust flappers

View attachment 224839View attachment 224840
Bondo,
So I've attempted to attach a couple pictures of my water shutters. Hopefully they load, let me know what you think.

Thanks'

Ayuh,.... the shutters look Ok,... swappin' 'em is yer choice,... they're Not supposed to be shut Tight,...
Don't look burnt at all,...

I would shop 'round, 'n find the "Kit" to put 2 piece manifolds, 'n risers on it, before it hits the water again,...

Loose "Batwings" are a tickin' time bomb, just waitin' to Ruin yer motor,....
Honest, seen it happen a few times,...

That new "Dry-joint" system from Merc is the Cadillac of manifolds today,...

I'm runnin' the ole style center riser type myself,...
Just use the carbon metallic gaskets from Mercruiser, regardless who's manifolds ya run,... clean, 'n dry,...
 

chilltech

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Re: exhaust flappers

boat exhaust 002.jpgboat exhaust 003.jpg
I figured I'd show what I saw when I took the manifold off, Rust stain is in #6. So if exhaust manifolds need periodic replacement why does the block and intake survive?
 

Bondo

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Re: exhaust flappers

View attachment 224844View attachment 224846
I figured I'd show what I saw when I took the manifold off, Rust stain is in #6. So if exhaust manifolds need periodic replacement why does the block and intake survive?

Ayuh,.... Yer manifolds are a breed of their own, which was a design to eliminate the gasket surfaces at the joint 'tween the manifold, 'n riser, which is the common failure point, 'n where they go Bad, requirin' replacement,....

It was a design Failure, due to core shiftin' in the castin' process,...

It's also a Saltwater thing,....
Here on the Sweetwater Seas,...
Manifolds, 'n risers will last 40 or 50 years, so long as they're Drained every winter,...

Intakes do in fact rot away in the brine, usually at the t-stat housin',...
When a block finally rots, 'n fails, it's usually worn out, 'n rebuilt once or twice by then anyways,...
 

achris

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Re: exhaust flappers

That rust stain in #6? That's the first sign of the manifolds leaving town.... You caught it just in time. Best ditch 'em and get a new 2 piece set... Personally, I'd be looking at OEM dry-joints. But there are a few places doing 'conversion' kits from one piece to two piece (but there are the old 'wet-joint' 2 piece)... If you'd like a list of the parts required to go straight to dry-joint, just ask...

Chris.....
 

chilltech

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Re: exhaust flappers

Thanks' for the help, I've learned a bunch already from this forum. So will the control cables and ignition module mount right up to the new exhaust elbow or will I need adapter plates? What's the best way to research the parts that I will need to purchase? I see a lot of conversion kits around, were all the 4.3L with the one piece set up the same? Or will it be more S# specific?
 

chilltech

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Re: exhaust flappers

When you say "dry joint" does that mean converting to closed cooling on the engine, and raw water cooling on the elbow only? I'd have to install heat exchanger?
 

chilltech

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Re: exhaust flappers

To get a little more specific the engine is 4.3L, S# L617639. I'm probably going to be boating mostly in fresh water but there is a lot of ocean near by so it cant be ruled out. I would be interested in the part numbers of both systems if possible.
Thanks'
 

achris

More fish than mountain goat
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Re: exhaust flappers

Dry-joint manifolds are nothing to do with closed cooling. I have some drawings somewhere showing the differences, I'll see if I can dig them out... All your shift cables and the shift plate should mount straight onto the new elbow, it has the mounting bosses cast into it, just like the batwings. And yes, all the batwing manifolds on the V6s were the same, and the conversion process is also the same for all of them.

Chris.......

Found the drawing....

attachment.php

attachment.php
 

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Fun Times

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Re: exhaust flappers

Dry joint is less susceptible to water leakage vs the non.

Also be aware that there is cold and warm dry joint exhaust risers. The newer engine models serial numbers 0M615000 and above are warm while serial numbers 0M600000 through 0M614999 are cold risers. You need to know what risers if any you have to install the gaskets in the correct order using mercruiser service manual #37. Boatinfo - Mercruiser Service Manual nr. 37 - 2002-Up - Dry Joint Exhaust

What is Dry-Joint Exhaust? - eBasicPower
 

achris

More fish than mountain goat
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Re: exhaust flappers

It actually just the configuration of the hoses and the elbow gasket that will determine if the manifolds will be warm or cold. Your current set up is effecively a cold manifold, and I see no good reason to mess with that set up unless you really want to go to warm manifolds (yes, it can be done, but you need a good understanding of the cooling system and how to go about changing it to warm manifolds).

I would go with this kit from the previously mentioned site Manifold Exhaust Kit for Mercruiser Dry Joint V6 4.3L 14 Degree Riser | Exhaust Manifold Kits for Mercruiser
But you are also going to need the tubes and rubber boots to connect the end of the elbow to the top of the exhaust Y-pipe. For that you'll need to use a few different parts drawings... Best if I point you in the right direction. (This is for just one side, so double your order!)

Lower rubber boot (Y-pipe to intermediate tube) 32-807458T
Intermediate tube -865947A01
Upper rubber boot (intermediate tube to elbow) 32-44348001
8 hose clamps 54-815504272.

Chris...
 

chilltech

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Re: exhaust flappers

Thanks for the info Chris. I will look into that more. I see that it's not merc parts though. I know to stay away from glm but never heard of osco, quality stuff? Also heard about valve overlap pulling water back into motor on converted 4.3s, any truth to that?
 

chilltech

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Re: exhaust flappers

So what is the advantages/disadvantages of warm or cold manifolds? Would think warm would be better to ward off condensate build up.
 

achris

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Re: exhaust flappers

Thanks for the info Chris. I will look into that more. I see that it's not merc parts though. I know to stay away from glm but never heard of osco, quality stuff? Also heard about valve overlap pulling water back into motor on converted 4.3s, any truth to that?

Osco are the next choice after OEM... And yes, you're right about the valve overlap, but it's not just the 2 piece that water will be pulled back with, they did it with the batwings too. If you have a read of your owners' handbook would will see that it states to run the engine at 1400 +/- 100 rpm when on flushers. Note, this is ONLY when on flushers. When the boat is in the water the back pressure on the exhaust stops the problem happening.

Chris........
 

chilltech

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Re: exhaust flappers

More good info thanks'. I don't have an owners manual so I didn't know that 1400 rpm on flusher rule. The last time the motor was run was at idol on flusher before she was put away. I'm still planning on changing manifolds out due to all the poor reviews but I'd say at this point that rust could simply be from the way it was last run. would you agree?
 
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