exhaust flappers.

[Surfshoptom]

First Post.
Just bought a boat. It's a 97 Regal 202 Something. I knew the Gimbal was bad so brought it to a mechanic. When he pulled off the lower unit, a couple of the flappers and some rubber parts were setting right there at the exhaust port.
He's going to replace the Gimbal and the bellows. How important are the flappers really? He said he wouldn't bother if it was his boat. It has a newer engine and may have flappers. It's $400 just to check.
It's an 04 4.3 Merc with Vortec parts.
What would you do?
Thanks.

 

[greg82255]

Re: exhaust flappers.

I'd replace them if it were my engine. Those flappers are there to prevent water from coming back up through the Y-pipe and exhaust manifolds into the cylinders. If they weren't necessary, Mercury wouldn't install them.. If you don't replace them and end up with water in the cylinders, it will be a lot more than $400 to fix. Just my 2 cents

 

[Bondo]

Re: exhaust flappers.

I'd replace them if it were my engine. Those flappers are there to prevent water from coming back up through the Y-pipe and exhaust manifolds into the cylinders. If they weren't necessary, Mercury wouldn't install them.. If you don't replace them and end up with water in the cylinders, it will be a lot more than $400 to fix. Just my 2 cents

Ayuh,... Agree....

If ya roll the dice, 'n Loose... That $400. will become $4,000....

 

[Surfshoptom]

Re: exhaust flappers.

I spose. it's gonna be a b*tch if we open er up and find it has good flappers and the ones we found we left over from when the first engine overheated.....
So you've heard of engines getting ruined cause they had bad or no flappers? My mechanic hasn't. He said "If you're aware, just always outrun the wake or turn to avoid it."

 

[Bondo]

Re: exhaust flappers.

I spose. it's gonna be a b*tch if we open er up and find it has good flappers and the ones we found we left over from when the first engine overheated.....
So you've heard of engines getting ruined cause they had bad or no flappers? My mechanic hasn't. He said "If you're aware, just always outrun the wake or turn to avoid it."

Ayuh,... Roll the dice then,....

It only takes 1 back-splash to Loose...

 

[Surfshoptom]

Re: exhaust flappers.

Does $400 seem appropriate for taking apart the exhaust on an '04 Merc 4.3? Is it something a guy could do himself easy enough?

 

[AZSenza]

Re: exhaust flappers.

Yes, Easy to do. From the Riser on top of each exhaust manifold to the down pipe (Y Pipe) is a rubber boot with at least 2 worm clamps on each end. Just loosen the clamps with a screw driver or about a 5/16" socket, the hard part is getting them out but not too bad, the flappers will be in the down pipe (Y Pipe). Once you figure it out, getting them on is easy, use a little dish soap to make them slippery on the inside, put the clamps in the middle of the rubber piece, slide each end on, then slide the clamps in place and tighten. Run the engine with Muffs to see if there are any leaks. First time out, check again (Have the screw driver ready just in case).
I ran open thru hulls for about a year, no flappers. Every time I came off plane I had to worry about water ingestion. (The Music of that engine was wonderful though and well worth the trouble but next time I WILL have flappers!)

 

[paultjohnson]

Re: exhaust flappers.

Never have done it but was wondering if a guy could get a hold of a borescope, or a plumbers camera, couldnt he run it up the exhaust with the drive off and see the flappers, or lack there of ??? Just askn'...............

 

[Bondo]

Re: exhaust flappers.

Never have done it but was wondering if a guy could get a hold of a borescope, or a plumbers camera, couldnt he run it up the exhaust with the drive off and see the flappers, or lack there of ??? Just askn'...............

Ayuh,... It'd be Alot easier to just Look, as described by AZSenza,...

Yer talkin' 4 hose clamps...

 

[Surfshoptom]

Re: exhaust flappers.

My mechanic told me the manifold had to be removed because it's the single manifold. It would be a lot easier if it was the double manifolds. That's why it's $400 and not so easy. It's an '04 with the Vortec heads??? just repeating what I remember him sayin.... Could be rememberin wrong.

 

[Bondo]

Re: exhaust flappers.

My mechanic told me the manifold had to be removed because it's the single manifold. It would be a lot easier if it was the double manifolds. That's why it's $400 and not so easy. It's an '04 with the Vortec heads??? just repeating what I remember him sayin.... Could be rememberin wrong.

Ayuh,... If you've got the 1 piece manifolds, REPLACE 'em, NOW...

They were a Bad idea, that went terribly Bad,...
They're leak prone, 'n will cost you yer Motor....
Convert it to the 2 piece units...

 

[04fxdwgi]

Re: exhaust flappers.

I spose. it's gonna be a b*tch if we open er up and find it has good flappers and the ones we found we left over from when the first engine overheated.....
So you've heard of engines getting ruined cause they had bad or no flappers? My mechanic hasn't. He said "If you're aware, just always outrun the wake or turn to avoid it."

"So you've heard of engines getting ruined cause they had bad or no flappers? My mechanic hasn't." That's interesting........ Is he new at this? Deffinately would have those shutters (flappers) in there and in good working condition. One big gulp of water from a following sea or big wake, or hard deceleration getting into a running engine (or even a non-running engine) and it could become a lawn decoration / planter. They are there for a reason other than for Mercruiser to make money on replacement exhaust parts.

Seems strange an '04 Mercruiser V-6 would have 1 piece manifolds / risers set up. I am not farmilliar with that specific setup, though. Thought they did away with 1 piece setups years ago for the better 2 piece design. I have only seen 1 piece setups on older inboards, so what do I know.

I replaced my shutters when I got the boat, after first full power run and engine began to run hot and didn't seem to have as much power as a big block should, kind of a dog... Pulled off risers from manifolds and inspected everything. Risers clean as a pin (almost new), but with wrong gaskests on them. Removed 4" exhaust hoses / elbows and looked down in the "Y" pipe. Shutters were toast. Removed old shutters and low and behold, who ever installed them last time, left the old ones down in the "Y" pipe. Some real Einsteins / 1/2 *****ed "mechanics" out there working on boats...... Can we say severe exhaust restriction here? Fished old ones out with a wire with a hook on it, installed new shutters, reinstalled hoses, elbows and risers (with correct gaskets this time, but that's another story). What a difference........................... Way more power at WOT, I can now get up on plane much faster, hit recommended 4500 RPM full speed far quicker, engine never got over 160 deg F and much lower fuel consumption.

Yes... Keep the shutters intact / installed.
Yes... Ditch the 1 piece manifold / riser setup (if that is actually what is on there) and opt for the 2 piece, as you can replace just the riser if / when it goes bad and not the whole exhaust and it makes maintenance much easier.
Yes... Remove / replace the old / dead flappers AND the ones lodged in the "Y" pipe. Those dead ones in the "Y" pipe are creating an exhaust restriction, robbing horsepower, increasing fuel consumption and possibly creating an overheating condition. The dead ones in the pipe are made of Stainless Steel and can eat a hole thru the aluminum "Y" pipe, creating a water leak into the boat. You would need to pull the engine out to change that pipe. If a hole is created, an unattended boat in the water could sink....
Yes... Get a new mechanic