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Thread: Outboard motor freeze prevention

  1. #1
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    Default Outboard motor freeze prevention

    Maybe someone can help me out: I have a 20 hp Honda on my boat. I asked at the shop whether I should place it "down" in the water or "up" out of the water when the air temperature is below freezing. They said "down". I researched as much as could on-line and came up with the same general consensus. Yet, when I go through the moorage, I see nearly all of the outboard motors (different brands) all "up" even when its below freezing. Are they courting disaster, is it brand dependent, or is putting it down in the water when air temp is below freezing an old wives tale?

    Does anyone have first hand experience on this?

    Thanks

    Ralph

  2. #2
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    Default Re: Outboard motor freeze prevention

    I always run and rinse the engine with fresh water after use. It sits on the trailer all winter and it's often below freezing and it's never been harmed.

    I was once told that leaving the lower unit in the water is taking a chance on getting water in the gearbox if the seal has any leakage at all. That makes some sense, but unless the leg has antifouling protection the algae and barnacles can grow on it. Also, a passing driftwood log could damage the leg.

    Also, the leg is aluminum and the bottom paint is probably copper. There should be a zinc sacrificial anode on the leg, but why invite corrosion when there's no advantage to leaving it down?

  3. #3
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    Default Re: Outboard motor freeze prevention

    Thanks for your comments. In your case, gibetheridge, do you leave the outboard leg up or down while your boat is on the trailer?

    I left out a few key pieces of information in my initial inquiry:

    My boat is moored through the winter in fresh water.
    I leave the leg "up" whenever its above freezing and lower it only when its below freezing, currently.
    I do get some sediment build up not severe and not much algae and no barnacles...
    I'd prefer to leave the leg up but that's not the advise I was given, hence the inquiry.

    Ralph

  4. #4
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    Default Re: Outboard motor freeze prevention

    For me, the engine is always down on the trailer, when not being towed. The theory being that freshwater could accumulate in the lower case when tilted up, then freeze, and crack something.

    In the slip, I leave mine down (salt water) because I'm more concerned with other boaters hitting it when tilted up, than I am with corrosion issues. It has been frozen in the ice while down, but nothing bad happened. I'm fairly sure the actual prop and lower case were in water below the ice.

  5. #5
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    Default Re: Outboard motor freeze prevention

    Yes indeed - below freezing you should drop the outboard down. True, if the seal is bad it can take water into the lower unit, but in several decades of outboard boating I have had one seal go bad and that one was torn up when I got mono-filament fishing line wrapped around the shaft - OOPS.

    On a trailer I have the outboard up while in motion and after parking I tilt it down. This will allow water to drain and render the engine freeze-proof.

    I have one outboard boat in the water year around and another on a trailer.

  6. #6
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    Default Re: Outboard motor freeze prevention

    I bought a 20hp Merc several years ago, used. When I went to pick it up he opened his hall closet and there it was, all warm and comfy. Nice house, nice closet.

    Aside from doing that leave it down unless the wells aren't bubbled. With the price of a new motor being what it is, I'd put mine in the closet or at least a semi-heated garage.

  7. #7
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    Default Re: Outboard motor freeze prevention

    I appreciate the responses I'm getting but so far everyone is confirming the "conventional wisdom" - tilt down in freezing temperatures.

    Has anyone experienced freezing damage after leaving their outboard tilted "up" or known someone that did? If so, what brand/size of motor was it?

    Thanks again

    Ralph

  8. #8
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    Default Re: Outboard motor freeze prevention

    Down. That's the position where all water passages will drain.

  9. #9
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    Default Re: Outboard motor freeze prevention

    There is a larger issue here even than freeze protection. Based on personal experience, IMHO, anyone who leaves a piece of aluminum in salt water for any appreciable period of time will at some point be sorry. I believe strongly that there is just not enough "nobility" difference between zinc and aluminum to justify leaving an outboard lower unit immersed for extended periods of time (or a stern drive, for that matter, but that is a different can of worms).

    I had a boat with a 6HP Johnsom in a well that did not permit tilting the motor up when not in use, and I cursed the arrangement the whole time I had the boat. Cooling water intake plugged, impossible to remove lower unit fasteners, seal leaks to lower unit gearbox lube, shift mechanism corroded, etc. So my take is, tilt it up when you are not using it.

    Boat on.

    Joe

  10. #10
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    Default Re: Outboard motor freeze prevention

    I'm firmly in the down camp for my 250-hp outboard when its in the water and temps are below freezing. Its colder out in the air and, an uutboard tilted-up doesn't drain completely. Usually this isn't for such a protracted period that I have gotten growth. And in colder waters, growth is less of a problem anyway.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  11. #11
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    Default Re: Outboard motor freeze prevention

    Of the folk who have OB's in the water this time of year, all I've noticed are up. But this is salt water which even when it freezes is pretty soft and unlikely to hurt anything. One guy, who runs the motor dry of gas at the end of the day by pulling the tank hose rather than shutting it down, also tends to pull the motor up just after he yanks the hose, so it runs for a few moments squirting all the water out of the cooling system. I always thought he was just in a hurry but maybe he has a plan.

  12. #12
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    Default Re: Outboard motor freeze prevention

    That's good practice he's got Ian, and if he's using the boat every day--or most days--its dandy. But for a recreational guy, who might not use the boat for a week or two, the gearcase torpedo and water intakes are in a "catch rain" position tilted up. Any precipitation might get in and the freeze, and then....maybe nothing, maybe something. That's my thinking anyway.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  13. #13
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    Default Re: Outboard motor freeze prevention

    I started the post to ferret out any first hand experience of actual freeze ups but so far no one has mentioned any...As with Ian, I've observed people leaving their motors out of the water in freezing weather and am wondering: what gives?

    I agree with Kevin about leaving a motor tilted down in salt water for extended time but mine's in fresh water so a few days here and there doesn't seem so bad.

    I have similar concerns mentioned with all water not draining out, collecting in prop hub, etc. in freezing temperatures.

    Maybe no one would want to admit in writing to freezing up their multi thousand $$ motor and risk the feedback...if that's the case, just say - "this guy on the slip next to mine..."

    I'm going to continue to tilt up except tilt down in freezing temperatures unless compelling, new data is offered.

    Thanks and hoping for an early spring -

    Ralph

  14. #14
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    Default Re: Outboard motor freeze prevention

    Quote Originally Posted by Ian McColgin View Post
    Of the folk who have OB's in the water this time of year, all I've noticed are up. But this is salt water which even when it freezes is pretty soft and unlikely to hurt anything. One guy, who runs the motor dry of gas at the end of the day by pulling the tank hose rather than shutting it down, also tends to pull the motor up just after he yanks the hose, so it runs for a few moments squirting all the water out of the cooling system. I always thought he was just in a hurry but maybe he has a plan.
    Maybe he plans an early impeller failure. And carburator fouling. My earlier advise was predicated on trailer storage, in that case water retained in a tilted lower unit could freeze and cause damage.I'd suggest leave it down either dry or wet stored.

  15. #15
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    Default Re: Outboard motor freeze prevention

    Ralph,
    It didn't happen to me...but the teenage son of the lady I sold the motor to, for his Christmas gift. It was a very nice 9.9 / 4 stroke Suzuki. He had left it "üp" after a duck hunt. It froze and cracked the block.
    Taught us both a lesson, his' expensive!
    Simmons18

  16. #16
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    Default Re: Outboard motor freeze prevention

    Simmons18,

    Thanks for sharing; that's what I was looking for. I'll also be seeing if anyone at my moorage had any damage come this spring with all the motors left up through the winter.

    Would be nice if there were an easy way to drain all the water on an outboard in the "up" position. Not yet aware of it.

    Ralph

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