Temperature and time for lower unit to freeze

[th365thli]

Obviously water freezes at 32 degrees. But as always it's not that simple. A cup of water outside for 2 hours at 32F isn't going to freeze. That same cup of water at -5 for will probably freeze pretty quickly.

The question is, at what temperature should we start being concerned for water in LU to freeze and start doing damage? I ask this because last night it got down to 30 degrees. Day time temperature Saturday was 54, high of 63 today. The boat was in a non-insulated enclosed storage space. Most of the water was drained out, but there was maybe less than a cup left when I checked this morning. I'm not too concerned because it should've been at least a few degrees warmer in the storage space, and I don't think it was cold long enough. But interested to see what you guys say.

[bass-action]

I would say when it starts hovering around 32 and teens at night. Why is there that much water in there?

[th365thli]

I would say when it starts hovering around 32 and teens at night.

I take it you mean high of 32?

[bass-action]

yes

[th365thli]

I would say when it starts hovering around 32 and teens at night. Why is there that much water in there?

Looks like you edited your post with a question. I was at a tournament Saturday. I normally tilt the motor for a few minutes down to drain most of the water, but had I known about the temps I would've taken more action to drain the last drops

[XingEyeballs]

We fish the river up here in the middle of February (might be daytime highs of 20’F and lows below zero). Trim the motor all the way up, wait few minutes, and then all the way down. Store it all the way down and you’re going to be just fine. Only thing we have to watch is don’t use your live wells and keep the actuator in the recirculate location when on the water.

[th365thli]

We fish the river up here in the middle of February (might be daytime highs of 20’F and lows below zero). Trim the motor all the way up, wait few minutes, and then all the way down. Store it all the way down and you’re going to be just fine. Only thing we have to watch is don’t use your live wells and keep the actuator in the recirculate location when on the water.

Thanks, I'm familiar with the processes to prevent water in the LU, just wondering what would be "concerning" temperatures I guess for my curiosity. You did answer my other question which was how cold can an outbaord run.......high of 20F is too cold for me haha...

[itsahog]

I would think it would have to be in single digits and highs stay below freezing before you would have to be too concerned. Like you said inside storage is a little bit warmer, and the water not only has to freeze, but freeze hard enough to expand and crack metal, it’s going to have to stay below freezing for some time for that to happen. Also keep in mind that the water would have to be at a full level wherever it’s at, if it has room to expand when it freezes it’s likely not going to hurt anything.

[DrewFlu33]

The extent of what I do with mine every winter is trimming it all the way down and leaving it that way for a while....usually that's a couple days just because that's how long it sits before I move it or do something otherwise, but realistically if you leave it down for 5 minutes there's nothing but a drop or two left in it...not enough to do any damage. I suppose I also raise the front jack higher than usual, but I do that to drain any remaining water out of the bilge and livewells more than the motor. Different motors could be different, but my old Mercury does just fine through MN winters every year with this approach.

I guess the other piece of that is trimming it up just in case there's water laying in it that only runs out when it's trimmed up, but that happens when I trailer away from the ramp.

[bass-action]

Looks like you edited your post with a question. I was at a tournament Saturday. I normally tilt the motor for a few minutes down to drain most of the water, but had I known about the temps I would've taken more action to drain the last drops

From your original post,I thought you were referring to water being inside the case itself with the oil. Just keep trimmed down when not in use,like others said. It will be fine

[Basser100]

When I stored mine outside in the colder country I would just wrap the lower unit in a sleeping bag if I had used it recently and if it was really cold stretch would just put heat tape wrapped around it if used recently.

[oldmanwinter]

During the cold season on the water just to be safe after draing at the boat launch I will pour some plumbing antifreeze down the pee hole so that I don't have an issue of ice forming in the bottom end and trying to melt it before heading out on the next trip.

[catch5]

I’ve heard of people wrapping a heavy blanket around the Lower unit just for insurance.

[M1RT]

Trim it all the way down at the ramp, let the water drain out, trailer it home. Us folks in the north country have been doing this since the advent of the water cooled outboard engine without issue.

[Dave A]

First off there should not be any water in the lower unit, did you drain to check for water and refill with new oil which should be done before cold weather, if not I recommend in doing so, this way you know for sure there's no water to freeze.

[218_fishing]

Once you drain it at the landing you could also just do a quick start to get the rest out.

[th365thli]

First off there should not be any water in the lower unit, did you drain to check for water and refill with new oil which should be done before cold weather, if not I recommend in doing so, this way you know for sure there's no water to freeze.

I'm not talking about water in the gear case. I'm talking about water in any pockets or external areas, such as the area behind the prop, or cooling passages. If I found water in the gear case it would be at the shop right now. Although I appreciate the suggestions for keeping it trimmed down, that wasn't what I was asking. I know to keep it trimmed down, I was simply curious about the temperature in which water freezes fast enough to expand and damage the lower unit if there was water sitting in it, say at a hairline crack or a cooling passage. I think itsahog provided an answer I was looking for. I had trimmed down at the ramp and was just lazy Saturday night and didn't think to check the low temperature, otherwise I would've trimmed it down even more. I usually keep it level on the garage because I store it with the jackplate all the way down (per seastar instructions to keep pressure off the hydraulics).

[Finlander]

If it gets that cold out one may want to consider winterizing because its too darn cold to enjoy fishing. I moved to Florida to avoid this dilema!

[th365thli]

If it gets that cold out one may want to consider winterizing because its too darn cold to enjoy fishing. I moved to Florida to avoid this dilema!

Ha I would love to take the rig down to Florida one day to check it out. Just not during the hot summers.

[skennedy]

I wouldn’t worry about it at all my duck hunting boats sit outside during duck season . The Outboards get ran in really tough conditions .freezing temp at night and cold water in the daytime just lower the motor all the way down . Next morning when you launch the boat let it sit in the water for 10-15 seconds before you turn it over that way the water pump will free up . I only had one occasion where a small pebble got stuck in the water jacket and blocked the water from draining and it cracked the head on my 75 hp . Nothing Tougher on a Outboard than a duck hunter . The 75 hp motor is 22 years old now . No manufacturer failures other than my abuse . But it gets great Maintanence.