Winterizing questions

CurrentObsession

Petty Officer 1st Class
Joined
Aug 26, 2011
Messages
221
Getting ready to winterize a new to me boat this year.
Freshwater Twin 502 Mag MPI in a 2000 Formula 400 ss.

First pics shows raw water impeller to the left for drawing water from the B3 drives correct?

First pics also shows a sea strainer at the bottom of the pic that I am confused about its purpose, I mean I know it filters debris but I assumed it pics up water from a seacock on the bottom of the boat but I can't see underneath the motor as to where it comes from or goes to.

Third pic:
Is this a flush out system? If so, should I warm up the engine enough to open the thermostat and then pour in red pop until it comes out the drive?

Any help is appreciated.
 

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Buster53

Petty Officer 3rd Class
Joined
Jun 16, 2022
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Ok, please clear this up…you say it is a fresh water engine. Do you mean the boat is only used in fresh water or it is a fresh water cooled engine, meaning it has a closed cooling system with anti freeze running through the block.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
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48,283
Third pic:
Is this a flush out system? If so, should I warm up the engine enough to open the thermostat and then pour in red pop until it comes out the drive?

Any help is appreciated.
No. That is a guaranteed freeze busted motor

Follow the factory service manual

Always drain the whole system (exhaust, block, hoses, etc) after you change oil, etc, do the annual drive service

After draining, if you desire to add antifreeze, add it with a funnel
 

ROY WILLIAMS

Petty Officer 1st Class
Joined
Aug 8, 2022
Messages
377
THE outdrives are taking it out and the lube grease and inspected it .. also the bellows look it up worn issue ..
the engine is flushing it out of the clean water drinking .. then do the drain plugs of that engine water .... also the alcohol in the WATER engines ...
the spark plugs take it out and the marvel mystery oil is the one OZ. in the cylinder .......
I was my boat did the fall and drain the gas tank ...
did my gasoline of my truck ...in the gas tank ....THOSE boat owners are in full gas tank, in the fall of the winter ..
over 30yrs my engine ...
 

CurrentObsession

Petty Officer 1st Class
Joined
Aug 26, 2011
Messages
221
Ok, please clear this up…you say it is a fresh water engine. Do you mean the boat is only used in fresh water or it is a fresh water cooled engine, meaning it has a closed cooling system with anti freeze running through the block.
Sorry, boat is used in a fresh water lake, no salt.
No antifreeze or heat exchanger anywhere on this engine.
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
17,934
Getting ready to winterize a new to me boat this year.
Freshwater Twin 502 Mag MPI in a 2000 Formula 400 ss.

First pics shows raw water impeller to the left for drawing water from the B3 drives correct?

First pics also shows a sea strainer at the bottom of the pic that I am confused about its purpose, I mean I know it filters debris but I assumed it pics up water from a seacock on the bottom of the boat but I can't see underneath the motor as to where it comes from or goes to.

Third pic:
Is this a flush out system? If so, should I warm up the engine enough to open the thermostat and then pour in red pop until it comes out the drive?

Any help is appreciated.
First Pic . . .
Sea water pump and sea water strainer. Water comes from the outdrive (or a thru-hull fitting) and goes to the sea water strainer first (where marine life/debris is captured) then onto the sea water pump.

Third picture . . . that is a flush adapter. It allows you to get water directly to the sea water pump, rather than pulling from outdrive or thru-hull fitting.

Posting a few pictures of the engine from a greater perspective will help.

Your boat may have a few things that are not spelled out in the Merc. service manual, but you should really have the proper manual for your engines to determine the best approach. The method that you described is probably wrong, and may lead to a cracked engine if you are in an area that gets to below 0˚F over the winter.

The reason that I say that is because the flow through the cooling system is not sequential . . . Water goes to the exhaust and the engine both at the same time in a 'parallel' fashion. So, will the anti-freeze. Within the engine itself, the anti-freeze 'mixes' with the existing water rather than a sequential flow, leaving a diluted anti-freeze mix even after 5-6 gallons of AF have been pumped through the cooling system.
 

Buster53

Petty Officer 3rd Class
Joined
Jun 16, 2022
Messages
78
Sorry, boat is used in a fresh water lake, no salt.
No antifreeze or heat exchanger anywhere on this engine.
Ok, just for future reference, that engine is referred to as RWC, raw water cooled. An engine with closed cooling (anti freeze running through the block) is FWC, fresh water cooled.
 
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