Engine Exhaust Flap

[horkn]

they were optional on older nautiques.

its more of a safeguard than a necessity.....

that said, I replaced the one that broke on my Martinique before I used it again....

[TBMsNautique]

All great suggestions. From what you have all said, I think I should spend the $25 and put on a new one. The old one just didn't seem like it did anything other than maybe muffle the sound or direct the exhaust fumes downard. The flap seemed rather cheap because it was simply a rubber device with a rubber bend -- nothing mechanical. Even when the boat was on the lift the flap never completely covered the exhaust port. Just seemed somewhat useless given the quality of the flap and its ability to completely close the hole. I hadn't considered the critters that may make a nest over the winter -- had that problem many times with my dirt bike! Thanks for all the comments.

[horkn]

fwiw, the 3" flap i got from my dealer was 13 dollars.

if you have a single outlet exhaust, it it a bigger one I think, and maybe a tad more $$, but hopefully not 25 dollars.

[ag4ever]

the one thing nobody is considering is that the water has to displace the air that is already in the sealed exhaust system. there is no possible way that incoming water could a) compress the air enough to reach the heads or b) cause enough pressure to force the air to make the crankshaft rotate, which would allow the air an escape route.

you can get stainless exhaust tips on a malibu, and i am quite sure that indmar has done enough homework to keep from warrantying malibus if this indeed was an issue. on the moomba that i had, the flap was just that: a rubber flap that sealed nothing going either in or out.

my main concern would be the birds that and other varmints that may find it to be a suitable nesting hole when it was on the lift...

If the engine stopped when both the exhaust valve and the intake valve were open (during the overlap portion) then you could push the air out. But you still have to force the water up the exhaust, then through the manifold, and then into the engine. Just not gonna happen.

[tdc_worm]

If the engine stopped when both the exhaust valve and the intake valve were open (during the overlap portion) then you could push the air out. But you still have to force the water up the exhaust, then through the manifold, and then into the engine. Just not gonna happen.

i agree. plus overlap is not gonna happen on all 8 cylinders at once. i.e. where the engine stopped at.

[sanddragon2004]

just buy the 25$ part and be done with it. lol everybody has there own opinions on the matter. Fact is correct craft engineers felt it nessicary (sp?)

I know we have had this problem with boats on numerous occasions over the years in our shop which ended in replacement engines. U will do what you want obviously. I can tell you that just about every boat manufacture has them on for a reason.