seacocks on sterndrive

Ethan's Tank

Member
Jun 1, 2014
425
aquia creek.potomac river United States
Boat Info
2009 Searay sundancer 350DA with twin 496 seacores
2000 wellcraft 2600 martinique [old]
Engines
Mercruiser 350 5.7 EFI
Since water is drawn in by the inlet holes in the outdrive, is there a shutoff somewhere on the engine that can be closed to do maintenance??


I have twin merc 8.1 with bravo3 attached, usually haul the boat out in the winter and attach muffs to winterize and place coolant in the motor. This year, the boat is staying in the water, and I need to figure out how to winterize this year.
Everyone at this new marina has bigger inboards so they have a seacock that can be shut on/off to prevent water to get into the block, how does this work for sterndrives? I've been looking all around the motor and I don't see one for it.
I have looked through the manual and it says to empty with the 3 blue drain plugs and use the manual air pump to open the drain valves. When I open one of the blue plugs [starboard top plug] I get a lot of water coming out and it seems like its just water from the outside and not just the block....so much water it filled my bilge area fairly quick within a few mins.
 
there is no shut off if you dont have seacocks - the impeller probably wont stop water from coming in - i would disconnect the hose and plug it and drain the blocks if you're raw water cooled - if your closed cooling, the manifolds and block are protected - much easier to bypass the heat exchanger and drain it - either way I would STRONGLY suggest a bilge heater as it keeps the temps consistent and prevents condensation (and thus corrosion) inside and out of the motors - close up the vents too so the heater can do its job - like others, i dont suggest relying on it for freeze protection.
 
A bilge heater is a good ide but make sure it is and approved bilge heater and not a small space heater from Walmart.
 
there is no shut off if you dont have seacocks - the impeller probably wont stop water from coming in - i would disconnect the hose and plug it and drain the blocks if you're raw water cooled - if your closed cooling, the manifolds and block are protected - much easier to bypass the heat exchanger and drain it - either way I would STRONGLY suggest a bilge heater as it keeps the temps consistent and prevents condensation (and thus corrosion) inside and out of the motors - close up the vents too so the heater can do its job - like others, i dont suggest relying on it for freeze protection.

My engines are closed system, so part of it is protected.
Merc says there is a way to air pump drain the system out, but I never could get it to work
 
should be pretty easy to bypass the heat exchanger and other coolers......otherwise i just dont think there is a reliable way to do it in the water
 

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