How are y'all adding antifreeze?
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Thanks I thought this was good enough but wanted reassurance. I bought a bimini and the dealership will install in the spring so I will get them to loosen the bolts at that time for next season winterization.
For the past two winters I have just hooked a hose up to the raw water intake and put it in a bucket of marine antifreeze that is under the exhaust behind the boat. Then I just fire the boat up and let it run for about 20 or so minutes till I know I have the water flushed out of the engine. I thought this was correct. Is that not true? I don't drain the motor prior to running antifreeze in it.
I wont tell you your method is wrong, but here is some food for thought. The marine/rv antifreeze is best at 100%. Its not meant to be diluted with water, like automotive antifreeze. For this reason, theres no way to really say what the freeze protection level is, once diluted as you have done. Its a guess at best.
I will admit, that I did basically the same as you, on a boat I used to own. It was too hard to reach the drain plugs, so I just cycled a few gallons of the pink stuff through it. Down here in NC, we get cold spells, but not long cold periods. I was completely comfortable with what I was doing, because I knew I was diluting the antifreeze. Owned that boat for 4 years and never an issue. After getting the tow boat after that one, we rode year round. I would just drain the water on the boat ramp, put the plugs back in and tow her home. Boat was turn key ready for the next warm day and I never used the antifreeze again. Once I figured the routine out, it only took about 10 mins to drain block and put everything back together.
Marine antifreeze looses its protection dramatically if its diluted. Sucking it up into a non drained engine at idle will give you a false sense of security. Take a thermostat with a thermometer and put it into a pot of water on the stove. You will be surprised how little it opens at 160. Now you tell me how long its going to take to get all the water out of the block and diluted with the antifreeze? So if you use 5 gallons of antifreeze and you do manage to distribute it with all the water in the intake line, block, heater, exhaust manifold, muffler(yes , lots of water in the muffler-try draining it sometime)....you have diluted it in half or more.....your protection is greatly reduced and at idle pressures you are luck to have fully reached all the passageways in the block.....plus your spending 20 minutes of running the motor......why not just drain the block, and the intake lines then the antifreeze will go directly into your block and the dilution wont be as great.
Or you could run it for 20 plus minutes and check the specific gravity to determine the diluted burst protection......
A solution of -50 antifreeze diluted in half will only provide a burst protection of +15 deg F.
The first year I owned the boat I did drain everything per the thread with pictures on here. The following year I had to replace an exhaust manifold due to a crack in it. If I need to drain the water and then run antifreeze then I will. I just didn't know.