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butter
07-14-2006, 01:51 PM
Yesterday on the water, I discovered the flap on one of my exhaust flappers was missing (or had been torn off by someone?). My question is whether I can get away without it for a day or two, if I am careful coming off plane, and reversing? I understand the risk is sucking water into the motor, hydrolock, and/or seizing. I am just unsure how critical the flapper is for preventing this. Sorry for the dumb question. Thanks for your help!

André
07-14-2006, 01:54 PM
Cut a temporary one in any rubber you got like a truck mudflap or similar...

EFiles
07-14-2006, 02:28 PM
Had the same thing happen a couple weekends ago. Noticed on Sat. morning. Didn't want to lose a weekend on the water so I went out anyway. I was careful slowing down and backing. No apparent adverse affects. This may have been a dumb thing to do but I seem to have gotten away with it. Got new ones from skidim that I'll be putting on before I go out again.

I'd be interested to hear someone more knowledgeable than myself weigh in on this. My thinking was that the exhaust put out enough pressure to keep the water out and was holding the flapper open most of the time anyway. The skidim catalog talks about engine dieseling causing water to be sucked back into the engine. The way these things are designed it looks like they would be more effective at closing off in the event of suction from the engine side than they would be at stopping water that was simply flowing toward the transom.

east tx skier
07-14-2006, 03:18 PM
So how much of a seal should you have from them. You can hear water coming in the pipes on mine when you come to a stop and turn off the engine. When you restart, it spits water out the pipes. I have flaps, but they aren't exactly water tight and have been considering replacing them.

TMCNo1
07-14-2006, 03:37 PM
Once the boat is stopped and the engine is cut off, water will go into the pipes and mufflers because they are not watertight. When you crank the boat up, it will blow all the water that has seeped in, but if the flaps weren't there and the pipes were full of water, then any wave surges and the like may force more water into the pipes and up into the manifolds, then into the engine. Order you a set from Skidim or get some at your dealer ASAP and replace them ASAP, just be real careful in the meantime.
Sometimes when we crank up on the water after the boat has set for a while the cranking of the engine will blow the flaps up and they catch in the slats of the platform and won't come loose unless I do it by hand, so I keep a check on them during the day.

east tx skier
07-14-2006, 03:40 PM
So No.1, if my flaps are intact and still cover 99% of the opening, I should be okay?

etduc
07-14-2006, 04:10 PM
Sitting still a the water will seek it's own level. Since the exhaust elbows are above lake level, water won't rise any higher, than lake level.
If a wave hits the back of the boat, without a flapper(i.e. - water under force). Water will rise higher. Another issue, if boat is carrying a couple of fat sacks, boat sitting lower in water, water will be higher in exhaust pipes.

ttu
07-14-2006, 04:12 PM
A friend of mine with a cc that has only one exhaust in the transom lost his flap last year and still has not replaced it. I say something to him all the time, but I don't think he really cares....

What type of damage is he looking at?

TMCNo1
07-14-2006, 04:26 PM
So No.1, if my flaps are intact and still cover 99% of the opening, I should be okay?


Yes, unless the rubber at the hinge area is torn or for some reason there is part or all of the flap is missing, as long as the entire flap covers the pipe is should be OK. The newer boats have the inside hinged style that do last longer and do seal a little better, but water still does get in the pipes!
I have been asked questions on this before and I usually tell the people to go ahead and get a spare set, for the "just in case factor", then examine the existing flap real good, then replace it with a new one just to see the difference. If there is no noticable difference, put the old one back on until you really do need to replace one or both. I was fortunate, several years ago, I found, by sheer chance, 4 pairs of 3" flappers at a Freight Salvage store for $4 a pair, bought all 4 sets!

butter
07-15-2006, 07:46 PM
Thanks for the input everyone. I went out and used it last night without any problems. I figure the exhaust risers are the primary defense against ingesting water into the engine, and the flappers are insurance against any freak set of circumstances that might force water past the risers, so I wasn't too worried. I like Andre's idea for a quick/temporary fix (although I didn't try it). At least now I feel more comfortable taking the time to order them from skidim, instead of feeling the need to make the 45 minute drive to the dealer to get them sooner.

butter
07-15-2006, 08:01 PM
A friend of mine with a cc that has only one exhaust in the transom lost his flap last year and still has not replaced it. I say something to him all the time, but I don't think he really cares....

What type of damage is he looking at?

If enough water is sucked into the motor thru the exhaust, it can become hydrolocked. (Water is essentially incompressible). Sometimes this can be easily remedied just by blowing the water out through the spark plug holes and changing the oil. In more severe cases, there can be serious internal engine damage, usually in the form of bent connecting rods, from what I understand.

TMCNo1
07-15-2006, 08:45 PM
A friend of mine with a cc that has only one exhaust in the transom lost his flap last year and still has not replaced it. I say something to him all the time, but I don't think he really cares....

What type of damage is he looking at?


If you have tried to convince him he needs to install a new one and he hasn't, then just let it go and if he has problems, it won't be your fault.

TMCNo1
07-15-2006, 08:55 PM
If enough water is sucked into the motor thru the exhaust, it can become hydrolocked. (Water is essentially incompressible). Sometimes this can be easily remedied just by blowing the water out through the spark plug holes and changing the oil. In more severe cases, there can be serious internal engine damage, usually in the form of bent connecting rods, from what I understand.


Very well stated and you are correct, but if you get to the point where you have to let the water out the spark plug holes, the real damage has already been done and a engine rebuild is next on the list.
A $13.99 set of exhaust flappers from skidim.com sent next day air, is cheaper than a $3,000 engine rebuild according to my calculator!:eek: