Exhaust Box Butterfly drain Valve replacement

jrowan · Apr 27, 2014

Don't know if you've fixed your problem already, but those fittings tend to corrode badly over the decades due to dielectric corrosion occurring between the brass drain plug screw & the water muffler. There's a lot of nasty exhaust gases mixing with sea water in there, & its amazing that water mufflers last as long as they do.
I would first soak the fitting perimeter with penetrating oil or PB BLaster type of oil, or equivenant that you can get in you locale. Soak it for at least a day. This may not work, but its worth a shot. Second, you can buy a fitting for a drill called a "screw extractor" which bites into the end of the broken off screw fitting & helps to back it out. Once you get it the drain plug out, then you'll have to find a replacement at a local chandlery.
The worst scenario is if you can't get the fitting out, then you'll have to drill it out & then tap new screw threads.

But if you shut off the raw water intake sea cock, & manage to get the engine started, then the engine will push the water out & your problem may be averted. Not sure about your exhaust design, but on smaller Catalina's you can release the exhaust hose above the intake side or exhaust side of the water muffler & then you could try to pump out the raw water from the muffler with a hand pump. I honestly would not even try to open the drain plug on my water muffler, as the fitting has got to be 30 years old & is likely corroded shut.

Good luck.

Exhaust Box Butterfly drain Valve replacement

melvyn.trigg

.

jrowan

.

melvyn.trigg

.