Logo
FULL SITE MENU

Why Do I Have No Exhaust Flappers

M

mtnxtreme

Member
1989 Mercruiser 4.3 Pulled my elbows , there are no flappers?? There are 2 holes, one on each side that possibly had a pin running thru it ?? My old Mercruiser had 2 notches in the pipe to hold the plastic flapper ends.
 
Could be they fell down the pipe and are still there they need to be fished out.

could be they were removed.

i don't have one and would remove it if it came with a boat.

Volvo does not install them any more and recommends removal in older engines.
 
mtnxtreme said:
1989 Mercruiser 4.3 Pulled my elbows , there are no flappers?? There are 2 holes, one on each side that possibly had a pin running thru it ?? My old Mercruiser had 2 notches in the pipe to hold the plastic flapper ends.
Click to expand...

Get a mirror and flashlight and look down inside the "Y" pipe and see if they are down in the bottom of it. Not too uncommon to happen. If down there, then you need to fish them out. Especially that S/S rod, as it will eat a hole in the aluminum "Y" and then you'll have a major job on your hands. If they aren't there, and completely missing, then someone may have removed them and didn't replace.

They are highly recommended to have on the Mercs, as they help prevent water ingestation thru the exhaust pipe in some circumstances and do not restrict the exhaust, especially on a 4.3. I don't know about the Volvos, but we are talking Mercs here.

In either case, new ones need to be installed.

My '92 454 had them both down in the bottom of the "Y" when I got the boat and fishing them out took 20 minutes using a wire with a hook on the end.

Auto parts houses also sell a gizmo with jaws on the end of a flexible shaft for grabbing stuff down deep where nothing else can fit / grab. Pretty easy.

I have a borescope I use to see in areas where the old noggin won't fit and tired eyes don't see too well.
 
Last edited:
Exhaust shutters were a good idea on paper but, they do nothing. They stop nothing. A few runs on the engine and the shutters get distorted. They were designed to stop water from entering the engine under certain circumstances IE.... Loss of Ignition while at full throttle or a full rpm throttle pull back to idle while underway.
 
mtnxtreme said:
1989 Mercruiser 4.3 Pulled my elbows , there are no flappers?? There are 2 holes, one on each side that possibly had a pin running thru it ?? My old Mercruiser had 2 notches in the pipe to hold the plastic flapper ends.
Click to expand...

Ayuh,.... Odds are, it's been run without water, or atleast Bad water flows....

Shutters are usually the 1st casualty of a Bad impeller...
 
Thanks guys so it looks like the vote is to delete them, I'll look and see if they are down there. Also when I run my motor are ears better than running the drive in a barrel of water, hate to ruin my new impeller.
 
Master mechanic said:
Your call.
Click to expand...

Have you ever tried the barrel, the only problem I was wondering if the water would get hot whereas the ears always has fresh cool water feeding, but always wondered if the ears could feed fast enough and al that water leaking past them and air pockets etc, but everyone does use hem.
 
mtnxtreme said:
Thanks guys so it looks like the vote is to delete them, I'll look and see if they are down there. Also when I run my motor are ears better than running the drive in a barrel of water, hate to ruin my new impeller.
Click to expand...

Ayuh,.... Use muffs, 'n a hose with Good water volume....

'n,... Ya Need the shutters.... they'll save yer motor from turnin' into an Anchor....
 
Uh Oh now Bondo you got me thinking, the other thing that sucks is if I put new ones in how do I know how they install if there's none there to begin with?? Another question maybe you guys can help me with, hopefully without starting a new thread. Where my water inlet hose hooks on at the transom, when I removed that hose, there was a rubber spacer bushing on there, like the guy had the wrong size hose and installed a smaller hose piece on there to bush it up in size, doesn't look very safe, but my bud says his boat was the same and saw another like it. Is there a certain hose to put on here to do away with that or is that factory???
 
I'm gonna replace all my hoses, should I do the spacer to, do they fail, does it have a correct name, besides spacer LOL? Also on the hoses, are they marine specialty or can I use heavy duty automotive ?? Some are pre formed but looks like I can use straight hose? Or just cough up and buy the right stuff, don't need to get stuck out there !!
 
Buy Mercruiser soft parts for below the water line.

Put new flappers in - they take a few seconds to install. Sure, some hull designs don't cause water to wash up the exhaust, but some hulls try to push a tsunami up there every time you stop.
If you're picking up a water skiier or something, you don't want to be worrying about how fast you can stop.
 
mtnxtreme said:
Uh Oh now Bondo you got me thinking, the other thing that sucks is if I put new ones in how do I know how they install if there's none there to begin with?? Another question maybe you guys can help me with, hopefully without starting a new thread. Where my water inlet hose hooks on at the transom, when I removed that hose, there was a rubber spacer bushing on there, like the guy had the wrong size hose and installed a smaller hose piece on there to bush it up in size, doesn't look very safe, but my bud says his boat was the same and saw another like it. Is there a certain hose to put on here to do away with that or is that factory???
Click to expand...

Ayuh,.... Just like Everything else We work on,....

It'll only fit Right, 1 way....

Yer serial numbers should get ya the Right parts, 'n a Shop manual tells ya How it's done....
 
How will water backwash up the drive with the engine running ?

Say you need to come to a emergency stop, why can't a person turn the boat so the wave passes you by ?

It's what i do anyway, when i pull back the throttle i do a gradual wide turn.

A skier goes down, doesn't the operator of the boat slows down and turns to pickup the skier ?

To the question of the spacer leave it in place. Want to replace? Replace with oem parts the price difference is is a few dollars, they fit better.

Some sites are cheaper then others for oem parts.
 
Back
Top