2005 Merc 350 MAG MPI Bravo 3 - Winterize Options

[kylejb2663]

Hey iBoats Community!

Been a while since I checked in here but looking for some options with my B3. We have a 2005 Bayliner 325 with twin Merc 350 MAG MPIs - we had the TSB completed to convert over to Thru-Hulls strainers for raw water intake.

That being said - I'm not sure if the mechanic actually blocked off the water flow from the Transom of the drive. We also do not have any sea strainers for the new water intakes (That's on my list)... but what is the best way to normally winterize.

My process is as follows:
Run the motor until T-Stat opens, hook up anti-freeze, run the motor.
Pull the 3 drain plugs on the motors and drains on each side of the block with sticking a small pic thru the holes to clean out any debris, pull the hoses and pour more anti freeze down.

I usually do a double method just in case the T-Stat did not open.
With "Why Knot", I'm not sure if I should pump up thru muffs on the drives or use a plunger style on the thru-hull water pick ups? Any ideas?

Thank a bunch, as always! Pic for attention!

 

[alldodge]

Thermostat opens and as soon as cooler water reduces the opening temp of the stat, it closes. Do your self a favor and pay no attention to if its open of closed. The stat will not be open long enough to replace much of the water, and at that its mixed so needs to be drained anyway.

Drain everything and make sure its all drained, then if you want to use AF, add it thru the hoses without the motor running.

This is the way I do the boats with inboards or sea strainers. Only difference with sea strainers, suck the water out of strainer with shopvac. Make a cap for top of strainer so air chuck with regulator and ball valve. Connect lid, turn air on and open thru hull valve and blow air out.

Close thru hull and disconnect air adapter from strainer..

If boat has heat exchangers, After draining some want AF pumped in. Then I disconnect strainer hose going to pump off strainer. Fill 5 gallon bucket and place hose in bucket. Fire motor up and pump it thru until about empty and shut down

 

[tpenfield]

My thoughts . . .

Keep in mind that the raw water coming into the engine is always 'cold' . . . yet the thermostat somehow seems to open after the engine warms up. I believe the incoming water goes to the engine block first and then goes to the thermostat. . .otherwise, the thermostat will always see cold and never hot.

So, as long as the engine is sufficiently warmed up, the AF going to the engine would be of similar temperature to the raw water that preceded it. Problems arise when there is a significant delay in switching from a raw water source to the AF source.

Big engines need lots and lots of AF, because the displacement of raw water from the engine is not a 1-for-1 with the intake of the AF. It is a diluting process, and on most engines some of the incoming AF will be directly diverted to the exhaust risers, missing the engine block and manifold entirely.

Draining is the key to successful winterization.