Flapper Valve

[LuckyPenny]

Can anyone explain the purpase of the Flapper Valve?<br /><br />What will I see or feel if one has failed?<br /><br />Thanks

 

[Bt Doctur]

Re: Flapper Valve

supposed to prevent water from rushing up the exaust when you stop suddenly and hydrolocking the motor.it can be inspected untill you remove the coupling on the exaust tube and look in it.<br />Ed

 

[Bski]

Re: Flapper Valve

Luckypenny,<br /><br />The flapper valves that I know of are in the exhaust tubes before they exit out through your stern drive.<br /><br />I just put a bunch of posts about them under exhaust flappers cause mine failed.<br /><br />They are supposed to prevent water from coming back up into your motor when you come to a sudden stop or go into reverse.<br /><br />I have a Volvo Penta and mine failed cause the rubber eyelets that they pivot on in the tube failed due to heat, one of them got stuck closed and would not allow my boat to acheive full throttle rpms, it would limit it to 3000rpm and wouldn't get up on a plane. I normally get past 4200rpm and come right up on a plane but with this my boat felt like it was trying to pull a huge load behind it and was being dragged down.<br /><br />Volvo Penta actually had a service bulletin which they sent me a copy of, it states that after extensive testing they felt that the valves were not keeping water out and that due to all the failures of them that they should be removed.<br /><br />If you need more info let me know, I have a .pdf of bulletin and can also direct you to links that show the assembly location etc.

 

[LuckyPenny]

Re: Flapper Valve

if they are removed as the bulletin says (I ahve not read it, just going by what you wrote) will the engine hydrolock?

 

[Don S]

Re: Flapper Valve

Many are putting to much emphases on what the shutters actually do and how the do it. They do not seal the pipe and prevent water from getting into the exhaust when you slow down, the engines exhaust does that. What it does, is slow down (Doesn't stop it completely) is water going up the pipe when the engine is not running. And waves hit the boat from the stern. If the risers are at the minimum book height or above, 99% of the time the shutters don't even get used.<br />One reason Volvo stopped using them is when they broke, they couldn't get out the exhaust tube and would block, or nearly block, the complete exhaust of air and water. This did more harm than good.<br />I have never had a problem with a SX style Volvo setup having water intrusion through the exhaust.