One forum member just started a discussion about leaving your engine trimmed up or down as temperatures drop and winterization draws closer:
Huggyd: I have a 25hp Mercury 4-stroke outboard. The father in-law has told me that since it’s an outboard we'll be ok to leave her in the water longer then an inboard because once the outboard shuts off water drains from it...? Really?
I talked to a friend who is an auto mechanic and he seems to think that while it’s true, you still have water behind the prop and you don't want to trim the motor up or the water may freeze and you don't know what will crack. My personal feeling is you'll always have water in the motor somewhere and if the temp goes down to 0 degrees or -2 degrees C, God knows what will happen and it’s not worth the chance.
So I am wondering if I should stand firm and just pull the boat out and call it a season or not worry about it just yet...Right now nights can go down to 5-ish degrees C and the days are still nice.
cwag911: If you leave the motor trimmed down, you'll be fine.
Huggyd: Really? Are outboards designed in that way, to let all the water run out? And I am assuming that leaving it trimmed down wouldn't cause a problem because of the volume of water around it wouldn't freeze whereas trimming up any water sitting behind the prop would freeze with the temperature of air, correct?
cwag911: You are correct. Where are you that it's that cold already?
rickdb1: They are indeed designed to drain when down, as Carl said. Before I put mine away for winter, I tilt it up and down a couple of times and then leave it in the down position.
belercous: I leave my boat in the slip year-round. I left my engine trimmed down one year over the winter. The next summer I didn't have reverse. My mechanic took one look at the lower unit and told me what I did. Replacement/new lower units aren't cheap. I'll never leave my engine trimmed down through another winter unless the boat is out of the water.
Huggyd: Yes and no, at night it can drop to around 4 degrees C (39 degrees F). I am on a big waterway (Severn River in Ontario) and there’s a good current/water flow all the time, so as for icing over, it’s still a ways away. I would just be concerned with any water sitting in any little tubes that freeze with the ambient air temperature if at night it dropped to 0 C (32F).
I am not leaving her in all winter; at some point in October or November if the weather still holds for that long I will be pulling it out and winterizing it, plus some other work to get it ready for next year.
Captain Tony: Look at the issue this way. If you have the ability, equipment and location to haul out and trailer store for the winter – do it.
I can verify that a 2-stroke outboard will drain down all water from the engine if it’s stored in a vertical orientation.
Having said that, I am compulsive enough to blow out the weep hole with low pressure compressed air, obviously drain the fuel filter/water separator if so equipped,
and low pressure air through the prop hub and do all the other winterization items on MY check list.
So cwag911, rickdb1 and belercous are all right on the money in their winter preparations.
I do, however, question the wisdom of relying on just this process for a 4-stroke. You did say your 25hp was a 4-stroke, right?
I seem to remember a Master Tech from Mercury warning that 4-cycle water-cooled outboards have much more upper-end water passages (plumbing) than the 2-cycles do.
I'd not want to chance it on a 4-stroke without checking with the engine manufacturer for their recommendations. Just a thought!
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