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Leeroy Jenkins

Custom mixing elbow failure

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37', 50 year old sloop has a custom mixing elbow on a below deck, fresh water cooled Universal M25. Picture a 21" length of 1 1/2 pipe that runs aft in order to get past the companionway ladder, and out of the galley. Then it rises aprox 24" to get 4-5" above the waterline where it does a 180 where the cooling water is injected and turns to hose, enters the waterlift muffler.  The rest is pretty standard. It was not supported and snapped off right at the exhaust manifold.  Aside from proper support which has been figured out, has anyone used a flexible damper in their exhaust system?  The location really does not allow for a shorter run or the hot pipe would be right in the galley.

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No, but that doesn’t mean it isn’t a good idea.  You need something flexible between the manifold and the pipe.  Better yet, make it all flexible. 

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It is always done on commercial engines to mount a flexible exhaust bellows between the turbo / exhaust outlet and the rest of the ridgid exhaust pipe. You then need to support the pipe downstream of the bellows. He can't make it all flexible because it's a long run of very hot, dry exhaust pipe.

https://www.triadbellows.com/products/exhaust-expansion-joints/

S.s. multi ply ones work well. They are off the shelf parts. You'll need to weld on a matching steel custom flange to match the exhaust outlet of the engine. Can be thin (3/8-1/2") 10-12mm mild steel plate. Downstream end can be flanged or weld to a threaded pipe union or whatever you are using for exhaust pipe fittings.

Once installed, wrap the dry part with high temp exhaust tape (like you see on old style motorcycles)

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Thanks Zonker. I was able to sort it out with smaller scale but similar stuff this afternoon. Basically high performance automotive exhaust parts. I've also re-designed it to be more like Calder's method...a lot less weight and not as sharp of a bend. And the fiberglass wrap of course because it's awesome. Four layers and you can grab it with your hand after a few hours of running. 

 

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look at the vetus water boxes, they contort to some odd shapes so you might be able to get it closer. The closer it is the better. 

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FWIW the exhaust wrap is often helpful.  We've always soaked/painted it with water glass and then a high heat paint after.  Seems to hold up better and not collect condensation as it cools.  

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Don Moyer has wet lift standpipes which should work for you.

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It's not the waterlift, it's all about location.  And gravity.  Zonker, I went with the bellows.  I see you're in Vancouver too; if you're ever in the same jam, Flex Tech in Langley was pretty helpful and does credit card sales without needing an account.  Thanks.

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Update:  after changing my username from cameron to leeroy jenkins, the exhaust system is now in good working order.  More than adequate support and no leaks.  It may be my imagination but there seems to be more water pressure and volume at the exit.  Thanks to everyone who offered advice. 

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