flushing outboards in winter

[Ed604]

Hello Tugnuts,
I store my boat in the water year round and I would like to boat in the winter months. I have a 302 with outboards and I do not have a trailer for the boat.

The marina where I keep my boat turns the water off during the winter months.
So, here is my question, will leaving the engines down in the water for 2-3 months cause me undue issues?
I would say that you could assume that I would use the boat 3-5times during those months.

I don't know how I can flush the engines which I normally do after every use during the other 3 seasons?

I worry about two things primarily:
1- Left over Salt crystals inside the engine ( my chief worry) causing corrosion
2- Marine growth damaging the finish on my lower unit

I was thinking that it wouldn't be so bad for any growth as the growth slows considerably in the winter cold, but what about the salt? is there anything that I can do if I don't have access to fresh water?

I have tried looking in the search for this but haven't seen anything.
thank you for any advice or Ideas.
Ed604

 

[Maggie Anne]

I had a single 300HP yamaha and would leave my boat in the water all winter. I would lift the engine out of the water and use a transfer pump with one hose in the antifreeze jug and the other in the fresh water flush connection on the engine and run anti-freeze through the engine until it came out the lower unit I did use the boat in the winter, and repeated this procedure each time, although maybe not as frequently as you are indicating plus you have twice as many engines so you would have more anti-freeze to go through. I've been told you could leave the engines down by a mechanic but not sure how reliable that was.

 

[BB marine]

It may be a PIA, if this is going to be your yearly routine a simple remote fresh water flush devise could be used. A 5 gallon capacity container filled with fresh water will flush a 300 hp block. The key is to do it just after use. The salt water drains from the block as soon as the engine is turned off and there is no water pressure from the pump. The salt deposits have not crystalized yet. The fresh water flush rinses the residual salt water that is coating the water jacket surfaces reducing the chances of corrosion and salt water deposits. 5 gallons per motor, the pump could be as simple as a drill pump with Garden hose fittings, a cordless drill and a couple of hoses.

Are you going to suffer extreme consequences if you do nothing, Probably not but if a Manufacture recommends a maintenance procedure there is a reason for it.

Leaving the gear case in the water is for one reason. It protects the lower unit thru hub exhaust cavity from freezing. This is the area forward of the prop. Water can collect in this cavity and the only way it drains is when the engine is in the vertical position (Down Position. If the cavity is full of standing water and there is a hard freeze the water freezing could cause enough expansion to crack the lower uint housing. I use the word COULD. In 30 plus years of working on outboards I have repaired less than a dozen ( I don't know the number but it wasn't a large number) All of the gear case freeze damages were on outboards that we stored on trailers during the winter and left in the full tilted trailerable position. The water entered the cavity from rain and snow fall filling it and then froze, expanded, cracked.

The rule of thumb is a outboard stored outside during conditions of freezing temperatures should be stored in the down position. The hazard is not normally during a day of 35F to 40F and temperatures dropping to below 30F to 20F over night then above freezing temperatures during the day. Especially if it is a boat in the water and water temperatures remain above freezing. The surface water temperature is going to help keep the gear case from a hard freeze. The times to be concerned are when forecast are predicted to be below freezing for a number of days in a row or a night time plunge in single digits.

This is the reason most marine technicians will recommend keeping the gear case under water. There is no fear of it freezing. The issue with that is marine growth and more metal in the water and an increase in anode deterioration. If I was going to do this I would have a galvanic isolator installed and hang a well grounded "anode fish" overboard while the engines are left in the water at the dock.

During moderate swings of below freezing temperatures. Pouring -200 below Propylene glycol antifreeze into the propeller exhaust outlet will mix with the water in the cavity and reduce the chances of a hard freeze in the cavity.

Decision's like this are double ended swords. There are consequences on either side. If it were my boat I would flush after use. Leave the engines tilted, pour antifreeze in the cavities. Monitor weather conditions and if there is a predicted hard freeze go to the boat and drop the motors down. Raise them when temperatures are forecasted to be moderate again. This method will reduce the time the midsection and lower unit are left in the water.

Good luck and enjoy your winter time boat rides!!!

 

[Ed604]

Thanks for the replies, so, a small garden pump and two 5 gallon buckets of water. Never thought of that, thanks.
I wish the Marina didn’t turn the water off but I understand why.

I could probably blow the engines out with air after the flush too, which would let me keep the engines up.
I also have rv antifreeze that I could mix in to the buckets for the flush,as it’s non toxic. Just in case some water is left in the lower unit.

These are doable ideas even if they are a little extra work.
Cheers,
Ed604

 

[BB marine]

I could probably blow the engines out with air after the flush too, which would let me keep the engines up.
I also have rv antifreeze that I could mix in to the buckets for the flush,as it’s non toxic. Just in case some water is left in the lower unit.

You don't have to worry about water in the engine block. It drains when the engine is shut down. Using anti freeze in the buckets really will do nothing it drains out. If I was going to but something in the buckets it would be a salt away mixture. The antifreeze needs to be a minimum of -100 because you are mixing it with water. The -50 will do little when mixed with water. You would pour the antifreeze directly into the through hub exhaust of the prop. That is where the water will be trapped.

 

[Ed604]

Thanks Brian, so as I understand what you are saying is that if I am going to leave the motors trimmed up after a flush. I would reach out and pour the antifreeze into the end of the propeller hub where the exhaust comes out? Do I understand that right, just dump the antifreeze right in there? I can see how the the 90 degree turn makes a little pocket that could fill up and have no where to go.

cheers,
Ed604

 

[BB marine]

That is correct. You should still monitor weather conditions and keep the mixture of antifreeze strong.