I have a 25 ft boat with a cabin. Not a go fast but I like the advice one here anyway. It has a 5.0 mercruiser. 40mph at best. My y pipe flappers have begun to make a lot of noise. My Question is do I really need them. My boat has the spacers on the risers. Think they are 3 or 4 inch. Has a boot on the end that goes to a down pipe that is approx 10 inches going down. Then another boot the hooks to the y pipe. Not looking for any gains, just wondering if it needs them.

Chris

Anyone

Ayuh,.... Shutters are cheap insurance,...

The only way to know whether they're absolutely Necessary is to run without 'em, 'n wait to hydro-lock yer motor,...

Yes they are 100% needed. Do not run without them. The can be replaced without much effort.

I agree,,,, look at it this way,,,, Merc would not put extra parts on the motor just because.

Cheap, and easy to change

How do you remove the flappers from the y pipe? Any pin? Cotter pin? How does it hold in plaçe?

there is a couple different versions of the water shutters aka flapper valves thru out the years - especially for the V 6 just saying. The most common ones are a rod that the shutters are attached to and there is slots on each side of the Y pipe that 2 small rubber gromment on each side holds the rod in place.

And just an FYI - Volvo penta does not use water shutters / flappers. Also in 1999 Volvo Penta came out with a SB to remove all prior year water shutters -

Merc does use them and 100 percent recommends they are installed and checked to make sure they are in full tact and operating correctly. NO biding movement or stuck.

But are they 100 percent a needed part - good question and here is why - most rec boat owners - half of them have water shutters burned up and or broken off - totally gone as they do not even know. Can not tell how many rec boats I have seen running around years without them - burn up and blown out the exhaust - or even stuck in the Y pipe and or stuck in transom assembly exhaust passage.

And again Volvo Penta does not use them period

Plus, when the metal parts break off and drop in bottom of y-pipe, you will get diff metal corrosion which will rot a hole in the y-pipe. One problem with OSO advice. You can and usually do get both sides of any point of view. So, check your boat waterline. Find a thru-hull or line on gimbal housing where it sits in the water at rest and see how far above that line the bottom of the top of risers is. That will give you an idea how safe you are from water ingestion from wave action. The number 13 or 14 inches sticks in my head, but can be found. The flapper are foubd-serviced by removing the rubber boot on top of y-pipe. Usually you hafta remove the elbow pipes to get boot off. The boots act as retainers for the pins and-or bushings. Check the boots for dry rot or heat damage while you have them off. BTW, They are banging and clanging cuz the rubber is burnt off and they are no longer sealing when closed.

All right! Changed! Thanks!

Care to share how you did it after asking the question?