winterizing an outboard?

boatman37

Well-Known Member
Jun 6, 2015
4,210
pittsburgh
Boat Info
2006 Crownline 250CR. 5.7 Merc BIII
Previous: 1986 Sea Ray 250 Sundancer. 260 Merc Alpha 1 Gen 1
Engines
5.7 Merc BIII
So my mother and step-father bought a pontoon this summer and with that dreaded W word coming I mentioned to him about winterizing. It is a 40HP 2 stroke Merc. No water systems onboard to deal with so just the engine and fuel system. I told him to dump some Star-Tron in the tank and run it a little while to get it up into the fuel lines. Also mentioned using fogger but not sure how on an outboard and have never even done that on mine.
Anything else need done to make sure all water is drained from the engine?
 
That's about it... some will change the oil and drive lube. Then just make sure to store with the drive all the down.
 
+1 on changing drive lube. If water leaked into the drive case and freezes it can crack your lower.
 
Stabilizer, run it. Change lower unit oil.
2 stroke is always fogged....nothing to do there.

Store vertical.
 
The only thing I would add to the above is to run the engine with the fuel line disconnected until the engine quits from fuel starvation. I never kept fuel in the portable tanks. If their boat has those store them empty along with the fuel line which should be mostly empty in a warm dry place. The fuel line has a fitting on both ends that when depressed will drain fuel. Pumping the primer bulb will expel gas when the fitting is depressed.
 
They have a 'permanent' mount fuel tank. 25 gallon or so. I told them to add stabilizer then add a little fuel to 'swoosh' it around then run it on the muffs. Sounds pretty easy...lol. They pulled it last weekend due to the flooding and probably aren't putting it back in. They are taking it to get a full canvas enclosure before winter but I told them they might not be in a hurry since they can keep it there all winter. Because of that I told them to have it winterized before they take it up there.
 
I've always fogged outboards. Remove plugs and spray some in each cylinder. Couldn't hurt........
 
Take it out of the water. Bump the starter in case a drop of water is lurking somewhere. Drain the lower unit lube. Done.
 
You can run a winterizing fuel mixture through from a separate tank like we do on our 8.1s. It's just fuel, extra two stroke oil and extra stabilizer. That will coat the engine and keep the fuel in the lines in good shape. The extra oil will burn off quick in the beginning of the season. Also make sure to store the engine down so that any water drains.

-Kevin
 
I'm a little north of you in central new york, gets kinda cold :) as such, I drain not change the drive lube. I put the fresh in on spring start up. I trailer not rack, so my outboard is tilted up in trailer mode, since it can't self drain, the lower unit is wrapped to prevent water intrusion. I also shrink wrap the boat, as we average 120" of snow, since I take it in on trailer to be wrapped, I pull the battery for basement storage on trickle before it goes to shop. Price is about the same per foot as inside unheated storage ($10-11/ft), but storage they include the tongue length so shrink wrapping is a little cheaper. I use non-e fuel, put a bottle of seafoam in the 30gal tank and fill it full. I've never had an issue not purchasing fogger (previously had a 1978 Johnson O/B). Pulled plugs, spritz some Marvel Mystery Oil in, pulled breather, spritz some Marvel in. Probably not the right way, but has worked for me.
 
It is not a good idea to drain the drive lube and leave the gearcase empty.

Condensation can cause rust to form on the internal parts over the winter storage.
 
It is not a good idea to drain the drive lube and leave the gearcase empty.

Condensation can cause rust to form on the internal parts over the winter storage.
I was thinking the same. We will be changing the lube out. I will also mention to him about having a local shop do it. He is usually pretty picky about his vehicles so might want the boat done professionally. I'll leave that up to him.
 
It has been awhile since I've winterized an outboard. I bought a 13 foot Boston Whaler with a 40HP Mercury outboard that both boys used when they were old enough to legally boat. We kept that boat on a trailer in the layup season out by our pole barn. There was no way to "drain" the lower unit so I'm wondering how those of you who recommend this do it. The Merc had two screws on the lower unit, one high and one low. The procedure for changing the lube oil in the lower unit was to remove both screws and then pump in fresh lube into the bottom until fresh green Merc lube came out the top screw opening. This stuff was so viscous, it would not drain of its own accord. I never tried pumping it out so maybe that would have worked. Manual stated to look at old lube color for signs of water (chocolate milk colored instead of green). I used to change the lube oil and run the gas out out of the carburetor and that was about it. We always put a fresh coat of varnish on the bright work and covered everything with a tarp. Empty gas tanks and battery went into the garage during the winter. Was a nice, simple boat to own and operate.
 
Last edited:
I definitely envy these OB guys when it come to maintenance/winterization. They just bought it in June and are taking it to the canvas shop to get a full enclosure made for it so it might be sitting there for awhile as there will be no rush for it. Then we will be taking ours there in the spring for at least a cockpit cover. Ours has shrunk and leaks like a sieve (went through 2 bottles of 303 on it and the edges near the window frame still leak). If the budget allows we will be getting all new canvas but at a minimum the cockpit cover.
 

Forum statistics

Threads
112,943
Messages
1,422,707
Members
60,927
Latest member
Jaguar65
Back
Top