Anti freeze vs draining

chambers1517

Petty Officer 1st Class
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Aug 14, 2009
Messages
205
I keep my boat in our basement garage. I have not seen it below 52 degrees before except once when the garage door hit something and went back up. It was 28 that morning and scared me a little so I started running antifreeze through it. I have a tub I put under the drive. I also have a 110 submersible pump with a waterhose fitting. I hook the hose up to the pump, put the muffs on, put 1 gal of water and 1 gal of antifreeze in the tub and run the boat til everything gets hot. I figure antifreeze is better for rust than moist air in the block. What do you think?
 

bruceb58

Supreme Mariner
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Mar 5, 2006
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I would just drain it.

Out of curiosity, you use your boat in salt water?
 

rallyart

Lieutenant Junior Grade
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Jun 7, 2008
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1,191
I have my boat stored in an unheated garage seven hours from my house. It's never seen antifreeze as I simply drain the water and then drive the trailer some sot make sure any water still there gets sloshed out. It probably has not been colder than -20°F in the garage.
Moist air is not much of a factor for rust if the temperature is cold. For me, I'd rather not spend the money or waste the product putting in an RV antifreeze and I really don't want automotive antifreeze in my lake. My boat also has the plumbing for two heaters in it and I've never had a freeze.
 

Ned L

Commander
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Sep 17, 2008
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2,268
I figure antifreeze is better for rust than moist air in the block. What do you think? .................... Yes, you are correct. Though at times the benefit may be minimal (depending on temperatures and time duration).
 

airshot

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Jul 22, 2008
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All a matter of preference......air don't freeze..as long as you get it all out! Putting automotive antifreeze in your boat should not be an issue because you should test run your boat before you ever get to the launch ramp and be sure everything is in working order before ever getting to the launch. I use auto antifreeze in my boat simply for the anti-rust property but the boat is always test run in my large stone driveway to be sure all is in good working order and the antifreeze is flushed out.
Running on muffs and sucking antifreeze is always a gamble, works well for many but engines are way to expensive for me to gamble so I drain the block and manifold, remove thermostat and pour auto antifreeze into the block until full about 1 1/2 gallons. To me....very cheap insurance and my boat and engine is a 1983 and all original and yes I do my own maintaince but I do it by the book as I feel the mercruiser people know best.
 

chambers1517

Petty Officer 1st Class
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Aug 14, 2009
Messages
205
Freshwater use only. Here is my procedure. Run boat in driveway with pump and antifreeze. Let boat run until antifreeze in tub is hot and temp gauge begins to go above normal to be sure thermostat is open. Once the temp starts to climb fog engine turn key off. Drain oil and change filter while still warm.I like the thought of automotive antifreeze being in the engine for rust protection. Not as worried about freezing but it is nice to have it there just in case. I then remove the muffs and pump the antifreeze into jugs for next year or for the vehicles.
 
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edthearcher

Petty Officer 2nd Class
Joined
Sep 22, 2007
Messages
116
this will be my first year of running anti freeze through out my engine, altho it will be in heated storage. i will use 6 gal. of -60 west marine anti freeze. i will heat my engine up prior runing the anti freeze through the engine, than remove thermostat housing and pour some down the hoses. I live in wisconsin it gets cold here, dont want to take a chance of the heat going off
 

bruceb58

Supreme Mariner
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Mar 5, 2006
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You are worrying way too much about rust in the engine on a freshwater boat.

Just keep it dry.
 

UncleWillie

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Oct 18, 2011
Messages
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this will be my first year of running anti freeze through out my engine, although it will be in heated storage. i will use 6 gal. of -60 west marine anti freeze. i will heat my engine up prior running the anti freeze through the engine, than remove thermostat housing and pour some down the hoses. I live in wisconsin it gets cold here, don't want to take a chance of the heat going off

Heating the block before adding the antifreeze will do little unless you also preheat the antifreeze.

Drain the block. Remove the thermostat.
Place a kiddie pool under the outdrive to catch the over flow.
Pump in the 6 gallons through the muffs to flush the water out of the outdrive and the power steering and fuel heat exchangers.
Finally drain the antifreeze out of the block into the pool.
All the metal will be coated with the oily antifreeze. Air doesn't freeze.
Save the antifreeze in the pool for use next year. You can typically recover more than 5 out of the 6 gallons.
Next year, test a sample in your freezer to see if it wasn't diluted too much.
If weak, add one gallon of -100 antifreeze to the batch to freshen up the mix.
 

H20Rat

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Mar 8, 2009
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All a matter of preference......air don't freeze..as long as you get it all out! Putting automotive antifreeze in your boat should not be an issue because you should test run your boat before you ever get to the launch ramp

So... Where do you think that water goes then? Storm run off (aka antifreeze headed down your driveway, into the gutter) does NOT go through a treatment plant in 99% of the cities in America. It usually ends up in a canal/creek, and eventually into a nearby river.

Anyway, my routine is BOTH. First drain everything out, and then get pink RV antifreeze, and then finally drain again.
 

Chris1956

Supreme Mariner
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Mar 25, 2004
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Introducing antifreeze via the flusher device is a dangerous gamble, as you will never know the concentration in the motor, and you will never know that the entire motor has been treated. The simpler, more effective and proper way to introduce antifreeze is as follows.

After all other winterizing has been completed.... remove the block and manifold drain plugs ( 1of each on an inline motor, 2 of each on a V engine) on the motor and let the water drain. Pour straight antifreeze into the large waterpump hose, until you see the color at one block drain. Install that drain plug. Continue to add antifreeze until you see it at the other drain (v engine only) Install the remaining drainplug and fill the block with straight A-F.

Pour straight A-F into the manifold hose, until you see the color at the drain. Install that drain plug and fill the manifold with straight A-F. It will exit the prop as well. Repeat for other manifold, if you have a V engine.

Pour straight A-F into raw water hose until you see color at water intakes. This flushes the power steering cooler.

In the spring drain the engine and manifolds and save the antifreeze for next winter. My 4.3LX Mercruiser would take about 4 Gal to winterize. I saved the containers and refilled them in the spring, and put them on the shelf in my garage.
 

Starcraft5834

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Jun 2, 2013
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Dry storage is my vote.......:popcorn: wondering if moisture is a problem in a marine engine seems a bit silly to me......... moisture is a problem at 32 degrees.. it gets bigger! Air dont freeze....... Smokes way....... I respect that completely.........an ounce of prevention is worth a pound of...............hmmm new engine?? makes spending a few bucks on pink not such a bad idea;)
 
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Slide

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Aug 2, 2010
Messages
269
So... Where do you think that water goes then? Storm run off (aka antifreeze headed down your driveway, into the gutter) does NOT go through a treatment plant in 99% of the cities in America. It usually ends up in a canal/creek, and eventually into a nearby river.

Anyway, my routine is BOTH. First drain everything out, and then get pink RV antifreeze, and then finally drain again.


RV/marine antifreeze (propylene glycol) is non-toxic. This is why it is sold as RV/marine - because in small quantities (like the 5 gal in your block when you run it the first time) it is not harmful to the environment.
 

Maclin

Admiral
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May 27, 2007
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6,761
This should not be an Either-Or choice as the title refers to. If the choice is to put antifreze in, then for raw water cooled engines....

1.) DRAIN everything first.
2.) Use the RV/Marine antifreeze, not automotive, to pour in.

Closed cooling engines will have Automotive antifreeze in the closed side, and that side would not get drained. Drain the raw water side of heat exchanger and exhaust depending on configuration, and then pour RV/Marine antifreeze in.

Versus (get the picture?)

1.) Drain everything.
2.) Stop.
 

UncleWillie

Captain
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Oct 18, 2011
Messages
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RV/marine antifreeze (propylene glycol) is non-toxic. This is why it is sold as RV/marine - because in small quantities (like the 5 gal in your block when you run it the first time) it is not harmful to the environment.

The issue was about Automotive/Ethylene Glycol Antifreeze.

Putting automotive antifreeze in your boat should not be an issue because you should test run your boat before you ever get to the launch ramp and be sure everything is in working order before ever getting to the launch. I use auto antifreeze in my boat simply for the anti-rust property but the boat is always test run in my large stone driveway to be sure all is in good working order and the antifreeze is flushed out.

So... Where do you think that water goes then? Storm run off (aka antifreeze headed down your driveway, into the gutter) does NOT go through a treatment plant in 99% of the cities in America. It usually ends up in a canal/creek, and eventually into a nearby river.
 

JASinIL2006

Vice Admiral
Joined
Feb 10, 2012
Messages
5,756
Having visited this site for a couple of years now, it's interesting to see how this discussion comes up about this time every year. Personally, I drain my engine and leave it empty over winter. Maybe if I boated in salt water I'd think otherwise, but the added benefit of antifreeze (anti-corrosion?) doesn't see very great for my freshwater-only boat.

Moreover, I haven't done any official tally, but come Spring-time, it always seems there are more reports of cracked blocks from improper or incomplete winterization using antifreeze (compared to the 'air don't freeze' approach). I know it's possible to incompletely drain the block by failing to prod the holes free of crud, but it seems like the many variations on the antifreeze method make it more prone to errors. Draining the block and leaving it empty seems harder to screw up...
 

oldjeep

Admiral
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May 17, 2010
Messages
6,455
I never put anything in the old boat - draining it was simple and there wasn't any place for the water to hide. The new boat has heater cores, 4 tanks, 8 pumps and an engine with hoses running all over the place. Plan is to drain everything completely and then fill the block, heater and transmission with Banfrost 2000 -100 anti-freeze. The tanks and pumps will get some -100 as well and get run so that hopefully any water in the system mixes with the -100 and keeps it to the -20/-30 that I actually need
 

moosehead

Chief Petty Officer
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May 29, 2012
Messages
437
Drain it dry. Ours is stored in an unheated barn at 9k' elevation in the CO Rockies, it gets -30F many nights and stays subzero successive days. +10, Air does not freeze.
 
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