Transom Leak - 2008 Supra Launch 21 V

Greetings:

I have a 2008 Supra 21 V Launch with the Indmar 340 Assault.

I notice that water was puddling in the bilge just under both locations where the exhaust exits the transom. I determined this by lowering the boat into the water with the engine off. While minimal, it is puddling at both locations where the 8 inch? diameter rubber exhaust tubing interfaces the transom....not sure of the correct terminology. Anyway, this exhaust tubing is held in place with hose clamps.

The boat is 8 years old and I haven't touched the hose clamps. I was able to tighten the hose clamps yet I'm not sure if this will solve the problem without spending more time on the water with it. On the outside of the transom where the exhaust exits, there are about 6 screws that attach the rubber gasket/flap to the transom along with a hose clamp. While I didn't check the screws, I tightened the hose clamp.

One of my questions is what is the exhaust tubing connected to at the transom wall. I turned the screw on the hose clamp a number of times...is it possible to overtighten? I'm guessing there is some type of "pipe sleeve" that runs through the transom that the interior exhaust tubing and exterior gasket/flap connect to. Can a leak develop around this pipe sleeve? Any help on this is appreciated...thanks...John

The exterior "flap holder" progresses inside the hull as sort of a plastic thru hull adapter and you can crush or certainly distort them. If you look through exhaust flap on the outside you will be able to see the tube on the inside.....it's got about a 4" neck that your flex exhaust hose fits over. One of mine is slightly folded due to over tightening now but still watertight.

Thanks Ken. Your info is helpful. I spoke with tech support at skiers choice and he didn't mention any deformation that could occur but did mention the house clamp could be rusting and overtighting may break it.

Anyway he also indicated that the silicon could be worn out and indicated the redoing the silicon would involve removing the exterior gasket/flap what your referring to the flap holder. He didn't mention that this piece had a through hall adapter as your suggesting. I'll need to look through flap to check out. Do you happen to know where I could view the part online so I know what I'm dealing with? Thanks again...John

skidim.com sells the exhaust flange.

Attachment 17165

Thanks again Ken. I looked through the back of the flanges and slightly folded mine too. Both still leak a lttle bit and I don't think tightening the hose clamps any further will resolve the problem. It appears that I would have to pull out the flanges and run a bead of silicon (5200?) between the flange and the flex exhaust hose in order to resolve the problem. Any other ideas? Seems like pulling the flanges wouldn't be too difficult but I don't know if there are other issues that I might encounter. John

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Originally Posted by BeachFarmer

Thanks again Ken. I looked through the back of the flanges and slightly folded mine too. Both still leak a lttle bit and I don't think tightening the hose clamps any further will resolve the problem. It appears that I would have to pull out the flanges and run a bead of silicon (5200?) between the flange and the flex exhaust hose in order to resolve the problem. Any other ideas? Seems like pulling the flanges wouldn't be too difficult but I don't know if there are other issues that I might encounter. John

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Pulling the flange is very easy. Maybe try 2 clamps on each first? A bead of 5200 would certainly seal it......the con is disassembly in the future will be very difficult.

I replaced my flanges two years ago and ended up crimping them both resulting in a leak. I replaced them both again a few months later and have had no issues. Next time though, I might go with the stainless version for two reasons. First there is the crimping issue and second, water can get into the wood doughnut on the inside of the transom and cause it to rot. Both mine are in bad shape. When I replace them I'll buy the stainless flange and make a stainless ring to mount on the inside of the transom so I can bolt them in place instead of using screws.

Where do you get a stainless version with proper size... 3.5" hose diameter in/out and 6 hole screw pattern? Please share, I've been looking everywhere!!!

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