Go Back   Maxum Boat Owners Club - Forum > Maxum General > Engines
Click Here to Login
Register FAQ Community Calendar Today's Posts Log in

Reply
 
Thread Tools Search this Thread Display Modes
 
Old 12-29-2015, 02:15 PM   #1
Captain
 
Join Date: Sep 2015
Location: Chesapeake, VA
Posts: 526
Default Exhaust Flappers

On the topic of exhaust, the flappers in my Y-pipe (twin 1994 7.4Ls) are not in the best of shape. One was broken in half (missing half not found) and the others don't swing so easy. These flappers look like just a brass plate with some rubber coating that hinges on a pin. All the new flappers I see appear to be a caged assembly where the flapper is two flaps that both blow down whereas my old ones are a solid piece where one end goes down and the other up. So, these new style ones look even more restrictive to the exhaust.
Questions-
Am I seeing the pictures right? Are these new flappers right for my boat? Will they hurt performance at all? Bigger question I guess is do I really even need them? when would water back up into the engine and do these flappers actually seal well enough to prevent that?
Sorry for the long post, but I'd appreciate any insight.
__________________

speedysprocket is offline   Reply With Quote
Old 12-29-2015, 02:30 PM   #2
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 10,587
Default

The ones you are finding are correct and the only style I have seen.

The pipes diameter is large enough that no performance loss occurs.

Yes they are required for cases of coming off plane quickly as the wake collapsing can force water up the exhaust. While a little water can get past the flapper its job is to prevent an amount that would flood the engine.

I say replace them.
__________________

__________________
1997 Silverton 362, 7.4 Crusaders
1997 2400 SCR, 5.7 Vortec / Bravo 2

Mike
mmwjr is offline   Reply With Quote
Old 12-29-2015, 02:34 PM   #3
Captain
 
Join Date: Sep 2015
Location: Chesapeake, VA
Posts: 526
Default

Quote:
Originally Posted by mmwjr View Post
The ones you are finding are correct and the only style I have seen.

The pipes diameter is large enough that no performance loss occurs.

Yes they are required for cases of coming off plane quickly as the wake collapsing can force water up the exhaust. While a little water can get past the flapper its job is to prevent an amount that would flood the engine.

I say replace them.
I thought that was the intent of them, but thought the exhaust would keep the water out. I'll order them; thanks for the quick reply!
speedysprocket is offline   Reply With Quote
Old 12-29-2015, 02:40 PM   #4
Moderator

 
shrew's Avatar
 
Join Date: Apr 2008
Posts: 5,675
Default

Moved to new thread as post was hi-jacking another thread.
shrew is offline   Reply With Quote
Old 12-29-2015, 02:51 PM   #5
Captain
 
Join Date: Sep 2015
Location: Chesapeake, VA
Posts: 526
Default

Quote:
Originally Posted by mmwjr View Post
The ones you are finding are correct and the only style I have seen.

The pipes diameter is large enough that no performance loss occurs.

Yes they are required for cases of coming off plane quickly as the wake collapsing can force water up the exhaust. While a little water can get past the flapper its job is to prevent an amount that would flood the engine.

I say replace them.
Ok, microfiche says use the second pictured flap, but I found somewhere it said it doesn't work when the original flapper was pinned. Part number 807166A1
Is the first picture what I want? Part number 807166A3
Attached Thumbnails
s-l1600.jpg  
Attached Images
 
speedysprocket is offline   Reply With Quote
Old 12-29-2015, 02:53 PM   #6
Captain
 
Join Date: Sep 2015
Location: Chesapeake, VA
Posts: 526
Default

Quote:
Originally Posted by mmwjr View Post
The ones you are finding are correct and the only style I have seen.

The pipes diameter is large enough that no performance loss occurs.

Yes they are required for cases of coming off plane quickly as the wake collapsing can force water up the exhaust. While a little water can get past the flapper its job is to prevent an amount that would flood the engine.

I say replace them.
Quote:
Originally Posted by shrew View Post
Moved to new thread as post was hi-jacking another thread.
Sorry, thought it was relevant.
speedysprocket is offline   Reply With Quote
Old 12-29-2015, 08:13 PM   #7
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 10,587
Default

Quote:
Originally Posted by speedysprocket View Post
I thought that was the intent of them, but thought the exhaust would keep the water out. I'll order them; thanks for the quick reply!

At high rpms the exhaust gas may keep the water out however when backing down off plane the throttle is cut back and the exhaust gas pressure drops too low to prevent water ingestion.
__________________
1997 Silverton 362, 7.4 Crusaders
1997 2400 SCR, 5.7 Vortec / Bravo 2

Mike
mmwjr is offline   Reply With Quote
Old 12-29-2015, 08:15 PM   #8
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 10,587
Default

Quote:
Originally Posted by speedysprocket View Post
Ok, microfiche says use the second pictured flap, but I found somewhere it said it doesn't work when the original flapper was pinned. Part number 807166A1
Is the first picture what I want? Part number 807166A3

Not 100% sure but I think the first picture is the one you want. Check the manual for your boat.
__________________
1997 Silverton 362, 7.4 Crusaders
1997 2400 SCR, 5.7 Vortec / Bravo 2

Mike
mmwjr is offline   Reply With Quote
Old 12-29-2015, 08:19 PM   #9
Captain
 
Join Date: Sep 2015
Location: Chesapeake, VA
Posts: 526
Default

Quote:
Originally Posted by mmwjr View Post
Not 100% sure but I think the first picture is the one you want. Check the manual for your boat.

They didn't make these new style flappers in 1994. They no longer make what my boat came with. That's why I asked..
speedysprocket is offline   Reply With Quote
Old 12-29-2015, 08:23 PM   #10
Admiral
 
mmwjr's Avatar
 
Join Date: Feb 2012
Location: Essex, Maryland
Posts: 10,587
Default

Quote:
Originally Posted by speedysprocket View Post
They didn't make these new style flappers in 1994. They no longer make what my boat came with. That's why I asked..
If I recall correctly the new style are designed to replace the old ones.
__________________

__________________
1997 Silverton 362, 7.4 Crusaders
1997 2400 SCR, 5.7 Vortec / Bravo 2

Mike
mmwjr is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 09:15 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2024, vBulletin Solutions, Inc.