Winterizing & Antifreeze

I just finished winterizing my 4.3L mercruiser with -60 Pure Oceans marine antifreeze from West Marine. My Searay is in upstate NY in the Adirondacks where temps get to -40 a couple of times a winter for a few hours at a time. After re-reading some info about antifreeze and burst temperatures, it seems that from the time the antifreeze starts to actually form crystals at +7 degrees or so, pressure starts to build. Burst temperatures are apparently based on the temperature that copper pipes will burst. Can you safely assume that the whole engine block will be as able as copper to contain the pressure and still be OK down to -60?

You're good to go. It doesn't actually start to really expand until -60*. Did you get behind the t-stat (intake area) by removing the hoses and pouring the AF in that way?

Thanks for your response. This is a 2016 engine with the "single point" system. I let the water out through the large drain valve at the front of the engine and opened the blue drain plugs. Hopefully, it will work as advertised in draining the block.

mattradk said:

Thanks for your response. This is a 2016 engine with the "single point" system. I let the water out through the large drain valve at the front of the engine and opened the blue drain plugs. Hopefully, it will work as advertised in draining the block.

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It does drop water out from the majority of the block/manifolds, but you still need to force the water out from behind the t-stat. There's no way to magically drain that. Without doing that, you run a very real risk of cracking the intake manifold area of the upper block. Keep in mind that Merc will NOT cover improper winterizing for your warranty.

How did you introduce the AF back into the block, manifolds, etc?

I put muffs on it and ran the engine on a garden hose until the temperature stabilized. I turned the engine off, and drained the block with the "single point" valve. Then, I put the muffs on a 5 gal winterization tank filled with the antifreeze, put the muffs on the intake, and started the engine. It sucked the antifreeze into the "empty" block and, I hope, filled it.

OK, well, regardless of what youtube or other people might say, it's not going to get on the other side of the t-stat. It "might", but typically the stat closes quick enough because the incoming AF is not hot. The only guaranteed way to get all the water out and the AF into every nook is to drain, then fill through the t-stat housing hoses. Although, you could use the "bucket" method if you first remove the t-stat housing, remove the t-stat, then replace the housing. Reverse the the procedure when you're done (may need a new gasket, too). The other way would be to use, probably, 20+gallons of AF or drop the leg into a large vat of AF - both of those aren't especially user-friendly for a DIY.

Something else to consider is that the small drain hoses (quick drain setup) can get clogged with sand/debris. That would not allow all the water to drain out. Given where you are located, you'll likely in a deep water lake so that may not be an issue. But it's definitely something you should know about - again, that would absolutely affect a warranty claim. They should, ideally, be pulled manually and checked for blockage. The drain system works, but if it gets clogged then all bets are off.

For what it's worth, we usually "fix" a few engines every Spring from customers doing the winterizing themselves and using the bucket method or some other improper method. However, I'm an avid believer in DIY - just do it the right way and don't trust everything you read on the internet. Trust me, if there was a better way than drain-n-fill through the hoses, I would do it. In reality, the way I'm describing is a 10 minute procedure. (There's plenty of threads about winterizing and the drain-n-fill if you wanted to search and find out more about it).

mattradk said:

I put muffs on it and ran the engine on a garden hose until the temperature stabilized. I turned the engine off, and drained the block with the "single point" valve. Then, I put the muffs on a 5 gal winterization tank filled with the antifreeze, put the muffs on the intake, and started the engine. It sucked the antifreeze into the "empty" block and, I hope, filled it.

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That's exactly what I've done for years on my 5.0 MPI with a single point drain and have never had a problem my .02.

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Your still probably going to have a slightly diluted mix when your done. If it were my boat with those temps, I'd drain that system the old fashion way, Take the block drains out, water pump hose, fuel cooler, manifolds plugs, and leave the system empty.

Thanks again for the advice. I pulled the thermostat. The housing and the hoses leading to it were empty. I added some AF to the space and the hoses. It took about 1/2 gallon. Hopefully, that will take of things. It's a good thought on the sand and debris. The boat stays docked and doesn't usually get near a beach during the season. Mostly tubing and ferrying my wife on evening trips. But that doesn't mean my 30-something-year-old kids may not pull the boat up to a beach some time.

FYI, you don't have to pull the t-stat if you're pulling the hoses. Try one more thing - and this is not to "put you to work" :smt001 - but it is what I would do (and not being there to see exactly how much AF was put in, or spilled out, I'd rather you be safe than sorry). Take the big hose off the t-stat housing, hold it up as high as you can, and pour the AF directly in. You should see the AF come back out the nipple. Now, normally, this is where I would typically see anywhere up to about 20 or 30 ounces of clear water come out before the AF comes out. This is the stuff that is trapped behind the t-stat during the bucket method.

With you having removed the t-stat you may very well have accomplished the same thing - it kinda depends on how much you let "spill out" - I typically let it spill out till I see a deep AF color. I also pour it in as fast as I can as it seems to help push the water out, as opposed to mixing with it. More than likely you have some "mix" of water/AF in there, but given the amount of water that would have been behind the t-stat, compared to how much you've now put in, you're probably fine, though. For what it's worth, I would end up using right around 4 gallons to do a V6 (for the block, manifolds and intake hose/power steering cooler).

The fluid in the big hose and coming out the nipple appeared to be antifreeze. Having removed the thermostat and putting an additional half gallon in appears to have taken care of the thermostat area. Hopefully, things should be OK after having drained the block, run it while feeding AF, and dealing with the thermostat area.

When considering if the bucket method works, I think you need to consider where the people are posting from. There is a big difference between the Carolinas and upstate New York.

Personally I use the bucket method. We rarely get down to zero and when we do, my detached garage does not get that cold. I've seen temps down to 15 in my garage.