Water flow first time after winterization- Single Drain

[Bdaviskar]

2002 5.0 MPI 0m616214
Single Drain - Alpha 1 Gen 2

Hello, I have a question on water flow for the first time after winterization. If you drain your block completely, how exactly does water refill the block with the thermostat closed? Thank you for your time.

 

[Scott Danforth]

hose #12 in your drawing

 

[TyeeMan]

The thermostat has a little hole (like about he size of a wooden Q-tip) that always allows a little water to get past. It's kind of like this, your sea water pump constantly pumps water to the circulating pump on front of the engine, and it also pumps water to your exhaust manifolds/risers. Once the block is full of water and gets to X temperature, the thermostat opens allowing hot water to exit the engine as fresh cool lake water is pumped into the engine. When the t-stat "feels" the cool water it closes until the water reaches X temp again and opens.

That's the short version, looks like your set up has a splitter or manifold, so sea water might go to that manifold then get dispersed to various places. All water exits the engine via the exhaust manifolds and risers.

 

[Bondo]

Ayuh,...... Water, bein' a liquid, seeks it's own level,.....

The motor fills from the bottom, up,.....

 

[Lou C]

And that fancy Merc drain system, looks to be about 200% more complex, than a vastly superior, simple half closed cooling system, which is what they SHOULD have had as standard equipment, so the engine could operate as GM intended!

 

[Scott Danforth]

And that fancy Merc drain system, looks to be about 200% more complex, than a vastly superior, simple half closed cooling system, which is what they SHOULD have had as standard equipment, so the engine could operate as GM intended!

Agreed.

However the OP asked how his motor fills. In the overly complex merc system, hose #12 is the fill line.

If it was my boat, I would remove the single-point system just to prevent freeze damage when the system fails to drain a portion of the block

 

[Bdaviskar]

Thank you everyone for your responses. I do plan on replacing the Single Drain in a few years.

 

[QBhoy]

Thank you everyone for your responses. I do plan on replacing the Single Drain in a few years.

Or just remove the quick connect fittings to check on the system.
Does that drawing you posted indicate an engine driven water pump ?