Exhaust flaps??

[Hootreville]

I read on another forum how important they are, so I went out to look at mine. They are rubber and bent out a little. When I put the boat in the water I can hear the exhaust fill with water. Atleast I think thats what it is. My question is what is the purpose. The other forum stated the importanc of having them function correctly especially in reverse. If they are completely closed and water proof in reverse you are choking of all of your exhaust. This cant be good either. How does this work and when do I need to change mine????

[mmandley]

There main purpose is to keep excessive water out of the exhaust. Just like in your car you don't want a bunch of water in your pipes. The flaps are designed to keep water out in reverse and when the boat is idle.

The point of them is that when the boat is running and the engine is exerting pressure on the flaps they open and the engine is able to breath, push out the exhaust. If you don't have flaps then water will sit in the pipe, and when you crank up the engine you have a large amount of back pressure on the engine as the exhaust has to push all the excess water out of the pipes.

On older boat that have exhaust outlets higher up this isn't an issue as the pipes don't sit underwater.

Now this does make me wonder about FAE systems because there connected to boat exhaust pipes and ran deep into the water threw a single pipe, im guessing since both pipes are exerting pressure they blow out the water in the outlet tube easier.

As for when to replace them? I would think if they don't close on there own then its time, I think i saw them at Overtons site for pretty cheap.

http://www.overtons.com/modperl/prod...ID=1008&r=view

[zegm]

I just installed a new one on mine because it was missing. I am thinking it wasn't tightened at the factory since it is a 2008 boat with only 60 hours on it. ( I Wonder if it came off while towing the boat last summer on the interstate? Stacy have you seen it on the road by your house?)
They come in 3" and 4" sizes and need to be cut to fit. The best way to see how this is done is to pull off the old one and see how they did it.

[zabooda]

You tape them shut in the winter and you can keep varments from nesting.