I/O Winterizing question

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Jul 19, 2009
Detroit, MI
I've owned this boat for ~12 years. Since I purchased it from the original owner, I've always winterized it the same way he told me he did. The engine is a Ford 302 H.O. FI. It has a drain on each side of the engine block with two hoses that "Y" together to a third hose which has a threaded on cap and clips up next to the oil dip stick. Skipping the other steps.... With the engine up to operating temp running on the ear muffs, I shut it down, remove the cap from the drain hose and let the water drain. I then fire it up again on the ear muffs, but this time running on a hose attached to a big jug that I fill with a couple gallons of ethylene glycol. Run the engine until all of the antifreeze runs out of the jug and shut it down. Then drain the antifreeze from the block using the drain hose mentioned above. This is what I have always done to make sure there is some antifreeze in the engine and not water to prevent freezing. A friend of mine who has a similar setup told me it is not necessary to run any antifreeze through the engine and that simply draining the water from the block via the drain hose setup is sufficient for winterizing. Since the boat has always been winterized with antifreeze and worked fine each spring, I highly doubt that I would ever change my process. BUT, is my friends way actually acceptable? I would think that you still have water in hoses, passages, risers, etc which could stick around even after using the block drain and possibly cause an issue. I am incorrect? will water work its way out on its own and drain out of the block drains and be ok???
Your way works for sure. I would fill engine with 50/50 antifreeze/water and leave it, because would help keep insides from rusting and the water pump seals lubed.
I winterize my boat almost the same way- except I do not run it through the outdrives. But yeah, I drain the engines of water, fill it up with anti freeze through the tstat housing, and then I drain that too. Air doesn't freeze!
Keep on with your method. These are "car engines" they were not designed to absolutely drain every corner and cavity for winterizing. If you winterized a lot of Inboards ("car engines") and I/O's you will also notice that sometimes the drain petcocks lime over and do not drain at all unless cleaned out. You may not notice, especially if the hoses, etc are draining normallly. I have been heavily involved with boats for many years, and each year learn of another block that cracked during the winter, even though it was "winterized". Throwing in the antifreeze, then redraining insures that all the pockets and cavities are protected. Many of us have pulled the petcocks and hoses at the ramp, then after draining completely than driving home.......and amazed at how much more water came out when jostling and jiggling during the tow home. Yup, this was all trapped water someplace!!
The way your doing it will work if the t-stat is open all the way, and while it should be, is it? If you want to fog the engine and stall it fogging you need to coordinate that with running out of antifreeze in the bucket. I drain both sides of my 5.7L Merc and then pull the large hose going to the water pump and fill the engine with the pink antifreeze. I pour additional antifreeze into the risers, manifolds, intake going to outdrive. If you are confident that the t-stat is opening, then continue on doing it your way.
Way to involved. Warm it up, stick a hose from the ear muffs in a bucket of the pink stuff, run until it comes out of the exhaust; done. As your doing that fog the motor out.
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Originally Posted By: hattaresguy
Way to involved. Warm it up, stick a hose from the ear muffs in a bucket of the pink stuff, run until it comes out of the exhaust; done. As your doing that fog the motor out.
I usually open all the drain plugs on our mercruiser and stick a small paperclip to make sure all the plugs arent "plugged." After that put the plugs back run the pink stuff through the bucket with earmuffs as mentioned above.
It sounds like you are using normal antifreeze. Its best to use non or low tox antifreeze or the pink RV antifreeze. You really do not want to dump regular antifreeze on the ground or in the water.
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