Exhaust Elbows

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system

Exhaust Elbows

Postby jdpandlp » Sat Dec 30, 2017 10:43 am

While doing my winter inspections I found that the steel pipe used to redirect and connect the exhaust hose sections and the anti-siphon loop had lost the battle with thirty years of hot saltwater. My 39 express has 3 inch exhaust from the 4JHE. I found the problem by sticking an awl thru one of the threaded pipes connection two 90 degree elbows.

I replaced all of the steel pipe with centek composite fittings. For the 180 degree turn which redirects the exhaust back toward the stern (the express has a v drive) the turn was not in plane so I cut two centek 90 degree elbows and used West to mate the pieces. This allowed me to make a very tight 180 degree turn which was out of plane and would fit in the original space allowed. It also removed about 50 pounds from the boat.

The pipe looked fine from the outside but once disassembled showed a great deal of rust. Might be a good idea to thump the steel fittings with a hammer just to make sure. In my case I guess I can't complain about them only lasting 32 years.
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Re: Exhaust Elbows

Postby wcwcwc » Sun Dec 31, 2017 9:21 am

West epoxy is great stuff. It does have one weakness - heat.
Bill Cormack
Formerly Sailing F-36 "Hard Earned" out of New Bedford Yacht Club, Padanaram, MA
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Re: Exhaust Elbows

Postby jdpandlp » Sun Dec 31, 2017 12:03 pm

Traded e-mails with rep from West before using. Temperature at which West starts to soften is well above operation range of wet exhaust. I keep a temp log (taken with laser temp) of major engine systems such as alternator, exhaust mixing elbow, spots on the engine block and transmission.... For the exhaust system after the mixer the temps are about 90 degrees after running for a hours at heavy load. Think windless day in August in the Chesapeake Bay.

Temperature was a consideration but research showed West to be a safe system for connecting the modified Centek Elbows. The high temperature epoxy alternatives have a rigid cure cycle that requires a high temp soak such as 200 degrees for 3 hours. My wife is forgiving of my passion for White Wings but I would not be brave enough to use her oven for that.
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Re: Exhaust Elbows

Postby katorpus » Mon Jan 01, 2018 5:08 pm

I would think you'd want to wrap the whole works thickly in glass mat and epoxy where' you're "gluing" things together.

It's not unheard of for a wet exhaust to suddenly become a dry exhaust with the failure of the impeller or some kind of intake obstruction.

It wouldn't take long for the temp to rise enough to be beyond the range of what the epoxy could handle...and if it melts & blows out, you will be looking at a lot bigger repair job than replacing an impeller or diving to pull a jelly fish or plastic bag off of the intake seacock. You could also be looking at a fire in the engine compartment.

I'd sure want to rethink your decision to not use the high heat epoxy. There's bound to be an oven somewhere that you could use...or go buy a pot (of your own) that's big enough to hold it all and do it on the stove top with the vent hood going. How unhappy could she be over that?
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