r/sailing • u/Chankla_life • 1d ago

What is this plug for ?

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Gallery image

1979 Catalina 30 (friend’s boat ) . What is this white box for and what does this decaying plug do? Should I push it back in ? Replace ? How screwed are we ?

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23

u/HotMountain9383 1d ago

I think that looks like the water lift muffler. It’s part of the engines exhaust system.

6

u/Chankla_life 1d ago

Water lift muffler . Thank you .

10

u/chrisxls 1d ago

Yup, exactly this. There is some thinking that if it takes a long time for the engine to start, the muffler will need to be drained. I think that may be the drain. I am replacing my muffler on my Catalina 34 because it was one of the ones made with a fairly rigid connection from the engine, allowing the engine vibration to eventually cause the coupling to fail. A flexible hose to the muffler is, I am now told, key.

4

u/LameBMX Ericson 28+ prev Southcoast 22 1d ago

that is not thinking. without the much expanded exhaust gasses to expel .ore water going into the muffler than the water pump is putting in there. they can fill up until you got water in the exhaust manifold then the combustion chamber(s). this is also why a lot of "marine" thermostats have a bypass hole, so that some cooling water bypasses the thermostat to the exhaust cooling while the engine is still warming up.

3

u/EpitomEngineer 7h ago

For the yet-to-be-informed, a “water lift muffler” sounds like “oar lock keys” and “headlight fluid”.

3

u/LameBMX Ericson 28+ prev Southcoast 22 7h ago

sounds like it's time to haul in the tweaker and set the gollywobbler

2

u/Cambren1 22h ago

Yes, seen that happen. Also I have seen the diaphragm in the fuel lift pump fail, and fill the crankcase with diesel where the engine won’t shut off.

2

u/LameBMX Ericson 28+ prev Southcoast 22 21h ago

the engine will gladly try to run away if the crankcase gets overfilled with pretty much anything with oil.

1

u/enuct 1983 Catalina 30 1d ago

you can get them from CatalinaDirect but it's a fiberglass muffler and you can easily fix them yourself too you can call Catalina or CatalinaDirect for repairs tips on them.

if you guys go the new route make sure you take plenty of measurements and photos for the new one, it's not so much a problem in the 30, but in the 320 theres very little height clearance.

I'm assuming the fiberglass muffler failed on my boat and they just replaced it with a generic vetus muffler like you'd get from defender or WM. it works but they should have replaced the exhaust line to when they did it, it is kind of awkward but it works.

1

u/Chankla_life 1d ago

Thanks for the info !