Winterizing an Outboard Motor

Winterizing Your Boat, Motor
& Trailer

Before you put your boat away for the season it may be best to take a look at any even minor problems you encountered during your boating season & repair them then. This is a lot easier & usually cheaper then than waiting until spring rush. You can not expect the good fairy to fix it over the winter.

For those of you who are NOT fortunate enough to live where fishing can be done with a boat during the winter months, you possibly should consider doing this task. This would be especially helpful if you do not have covered winter storage for your boat & motor. Covered, in my book is not just a tarp tied down over the boat either.

The first step in winterizing your boat should be to make a list of all your winterization tasks. Check your boat and motor owner's manuals for manufacturer recommendations on winterization and review the topics below. If you are a new watercraft owner, consider employing the help of a friend with experience in winterization, or better yet, hire a professional to do the job

In this article we are covering both a trailerable & a moored boat.

2 Cycle Outboard Motor Winterization : It is what you can not see that can be harmful to your motor. This is inside of the motor itself. We will discuss a lot of things here that should be looked at in the boat & motor when put away for any length of time.

We will deal with 2 cycle outboard motors first. It is especially good to internally fog the motor as shown in the photo below. 4 cycle motors will require a slightly different procedure for the engine itself.

Fogging in this sense of the word here means to coat the internal metal parts of the motor with an oily substance so that they do not get a chance to rust or corrode during long term storage. You will find many different brands of fogging oil that even may be called by different names. They essentially achieve the same end result & that is to protect the inner parts of the motor when not in use for extended periods of time, especially if in colder climates.

Pump the fuel line bulb up, start the motor, let it run long enough to get warm with fresh water using flush muffs or a similar device attached to the raw water intake. Disconnect the fuel line but let the engine still run. Fog the engine. After the engine dies, use fogging oil in the cylinders to lubricate the crankcase, crankshaft bearings, cylinder walls and pistons. The plan is to fog the engine & shut it off with no or as little fuel in the carburetor as possible for the winter, so that all or most of the fuel is drained from the carburetor to prevent build-up of deposits from evaporated fuel & doesn't turn to gum or varnish.

The product being used in the photo below is as you can see a CRC product called Engine Stor. It comes in a 16 oz. pressurized can & sells for about $5.00 which should do many winterization jobs. The instructions say to "start the motor, (using muffs or a water hose adapter) & run the motor until it gets warm. To me, that means that you should be able to feel the block behind the flywheel become warm to the touch. Remove the carburetor breather if one is attached, & spray this liquid into the intake of each of the carburetors for from 5 to 10 seconds for each carburetor". I would recommend that the motor be running at a high idle. NOTE the motor will slow down somewhat like it wants to die, if it is a multi-cylinder motor, but if it is a single cylinder, it possibly would die.

As soon after all carburetors have been treated, let the engine die or shut the motor off. Pull the spark plugs & again spray a couple of squirts of your fogging oil into each spark plug hole. Now rotate the flywheel either by hand or with the manual starter rope a couple of revolutions to coat the inside of the cylinders with this oil. Put the spark plugs back in & replace the breather & cowling.

Let all water drain from the engine. Wash the engine down with soap and water to remove any foreign residue and rinse thoroughly.

If the motor has a fuel oil reservoir that injects the oil directly into the motor, refill it to proper height with new TWC-3 oil.

Replace Spark Plugs or Clean Them? What's the rule of thumb when it comes to replacing spark plugs ? Run till there's a problem, or replace them once a year, every other year, etc. ? There are lots of opinions on this one. Spark plugs are cheap so some folks just replace them every year. I personally clean & beadblast them, check the gap and put them back in. If I do replace them every 2-3 years, (depending on how much I run the motors) I save the old plugs for spares, sandblast & check the gaps on them so they are a usable spare set & vacuum pack them to keep corrosion off when stored in my boat tool box.

If you do replace with new spark plugs, be sure you get the same configuration so that you do not have a problem at the start the next boating season.

A fogging oil being sprayed into a carburetor of a Johnson 2 cycle 70 hp motor with the breather cover removed

4 stroke Outboard Motor Winterization : Check with your owners manual as to the proper procedure of you particular motor. Run the engine to warm it up then drain the oil while it is warm. This allows impurities to be drained away with the oil. Refill the oil to the proper level & change the oil filter if applicable. Remove spark plugs and use "fogging oil" to spray into each cylinder.

Let all water drain from the engine. Wash the engine down with soap and water and rinse thoroughly.

The Rest of the Outboard Motor : Also at this time, I would inspect & lubricate any motor pivot, or hinge point, throttle, shift rod or cable with a waterproof boat trailer axle grease or Lubriplate. This would also be a good time to look for loose bolts or nuts. Even replace rusty ones with stainless steel ones. Check the wiring connectors for corrosion. Do any cleaning that may be needed as you will probably have more time now than in the spring when the sun is shining & the fish are jumping. Clean the cowlings & the lower unit, use a detergent soap if need be to get any oily residue off.

Check the lower unit gearbox oil for contamination, this would usually be water may have leaked by the seals. About all gearboxes have 2 flat headed slotted screws that access the gearbox oil. Drain the gearbox, by removing the fill screw on the bottom & the check level screw on the top. If there is a Phillips headed screw nearby DO NOT TAKE IT OUT as it may be the shifting pivot screw & if removed can be a MAJOR problem replacing it into the internal shifting linkage. It may be best to replace this oil at this time, especially if there is any contamination. If this is the case, now would also be the time to replace the prop shaft seals & the drain screw washers.

If the oil comes out the bottom hole is a bluish or clear golden color, it will not be contaminated, so replace the screws & go for another year. If it is a creamy light brownish color, it has some water in it. If it is BLACK, then it is due for replacement. Let it drip for an hour or so & then refill the gearbox.

Use a gear oil recommended by the manufacturer if possible, however currently it may be beneficial to change & use a synthetic oil, which may cost a little more but will lubricate the gears a lot better. A Hypoid gear oil with a viscosity of 80 or 90 would be about right for most motors.

It is easiest to use a pump type unit that attaches to the top of a quart plastic bottle usually found on some of the gear oil bottles. Different motors will have different threads so you may have to purchase a adapter that fits your motor. In refilling, screw the hose fitting into the bottom hole in the gearcase, pump the oil in until it starts flowing out the upper hole. Replace the upper screw (this creates a vacuum & slows the oil draining out the bottom hole) using a new washer if possible, then remove the pump hose & quickly replace the lower screw & new washer. The reason for replacing the old nylon washers under the plug screws with new ones to ensure that there are no leaks of oil out or water in & the small cost is worth it.

Shown here the oil is the being pumped in the bottom & some overflowing out the top hole indicating it is full. Notice the clear bluish oil color. The plug screws are laying on the cavitation plate.

Remove the propeller, clean the shaft & splines. Inspect the prop blades & if there are any nicks or rock damage, with a hammer & a support block try to hammer the blade back in the same shape as the others if at all possible if the damage is minor. Using a file, clean any nicks out if applicable. If the prop shows more damage take it to a marine dealer for inspection or repair. Running a bent out of balance prop will produce a vibration that can be destructive to the bearings & or gears in the gearbox.

Apply a waterproof grease or Lubriplate to the splines (this assures the prop will come of easy at a later date) & reassemble, using a new cotter pin in the prop shaft nut. Be sure to replace any spacers either in front of or behind the prop in the same location that they came off from.

If your motor has a lanyard type kill button switch, check to see that it functions.

Store the motor/motors in a upright running position to assure all water has drained out & does not freeze internally possibly breaking the lower unit if you live in a cold climate.

Check the tiller cable & grease it by moving the steering wheel all the way one way, grease the rod, move it all the way the other direction & grease it again.

Inboard Motor Winterization : Run the engine to warm it up and change the oil while it is warm. This allows impurities to be drained away with the oil. Depending on your motor, a pump type unit may be helpful. Change the oil filter. Flush the engine with fresh water. Circulate antifreeze through the manifold by using a pickup hose from the waterpump to a bucket of antifreeze. Start the engine and allow the antifreeze to circulate until water starts to exit the exhaust. This process will vary slightly depending on whether you have a "Raw Water" cooling system or an "Closed Fresh Water" cooling system.

While you are here, change the fluid in your transmission. Remove spark plugs and use "fogging oil" to spray into each cylinder. Wipe down the engine with a clean rag or shop towel sprayed with a light oil or Bo-Shield.

Check the prop shaft & rudder stuffing boxes & replace the packing if need be if the boat is a true inboard. Check all thru the hull fittings for possible leaks.

Stern Drive : Check your owner's manual for recommendations by the manufacturer. Inspect the stern drive thoroughly & remove any plant life or barnacles from the lower unit. Drain the gear case and check for any water in the oil, (this will be in the form of a creamy colored oil instead of blue or black) which may indicate leaking seals and the need for repairs. Clean the lower unit with soap and water, repaint if needed. If your stern drive has a rubber boot, check it for cracks or pinholes, replace if needed. Grease all fittings including the universal joints. Also check fluid levels in the hydraulic steering or lift pumps.

Dry Storage For Moored Boats: Pressure wash the hull, clean barnacles off props and shafts, rudders, struts and trim tabs. Clean all thru-hulls and strainers. Open the seacocks or remove the drain plug to allow any water to drain. Check the hull for blisters if the hull is wood or fiberglas. If you find any that require attention, consider opening them to drain over the winter for repair later.

Boat Winterization : Wash down the exterior, at this time, look the hull over for scratches & if it is Fiberglass, there is a patch stick available that can be purchased in most matching colors that will fill scratches & not be very noticeable. If it is aluminum & if you have not used a protective coating on the bare aluminum, you may be best to get a soapy detergent & try to remove any staining. You might want to purchase a multi-purpose lubricant & corrosion inhibitor to spray onto this bare aluminum.

It would also be best to add fuel stabilizer/conditioner to your fuel tank if you have not already done. Fill your fuel tank to avoid a build up of condensation over the winter months. But leave a slight amount of air space (like the length of the filler hose) for expansion of the fuel when the weather warms up. Change the fuel filter & water separator. Purchase spares for next year.

Wash down the interior of the boat. You will be amazed at the fish scales, food droppings, etc. that can accumulate in small places.

Once you have taken care of the systems, pull your sonar screen, GPS units & radios out of the boat & store them in a warm, dry location. Check the antenna connections. Remove any other valuables, lines, PFD, fire extinguishers, flares, fenders, etc. If you have any navigational charts aboard, it may be best to also remove them to a warmer dry location. Over the winter, clean, check and replace these items as necessary. Open all drawers & lockers and clean them thoroughly. Turn the cushions up on edge so that air is able to circulate around them or, better yet, bring them home to a climate controlled area. Open and clean the icebox, refrigerator & freezer if applicable. If the boat has a cabin or convertible top & a back-drop, you might consider installing a small portable electric ceramic heater inside set at a low heat just enough to keep any mildew off.

Check your mooring & anchor lines for chafing. Replace them if need be. Are your mooring bumper lines long enough or need replacing. Clean & repaint or re-galvanize the anchor if applicable.

Check you Personal Floatation Devices (life preservers) Do they need replacing? Is the CO2 cartridge in you inflatable preserver in good shape? Did you get a spare cartridge after you accidentally pulled the rip-cord during the summer?

Check you navigational lights & any connections for serviceability. If you have a set of docking lights are they operational? If they are portable & can be plugged into a receptacle are these receptacles clean & operational along with the switch?

Is your emergency box with tools, flares, etc. functional. Remove the tools & clean any rust off, & spray with a corrosion inhibitor. Check the fire extinguishers. It is best to at least twice a year to remove the fire extinguishers, & shake them enough to uncake the internal foam that will have become settled in the bottom that may prevent the extinguisher will not function when needed.

Check your windshield wiper blades & replace if need be. Check the horn for function. Also clean out the fishbox or ice chest & deodorize it.

Covers : If you have a convertible top, especially if you use the boat in salt water, carefully unsnap all of the snaps & apply a silicone or even Vaseline to the inside of the female snaps. This will ensure that they do not get corroded & grown together during the winter & you may pull a snap out of the fabric next spring. Also you may inspect the male snaps & if corroded, use fine steel wool to remove that corrosion before it gets any worse.

Leave the convertible top on & snapped down, because if you take it off, the thin Plexiglas tens to shrink in cold weather & if you decide to sneak out in that nice day in the spring, you WILL have a hard time getting the top stretched enough to snap it on.

If you are storing the boat outside during the winter & you do not have a convertible top with a rear cover, invest in a cover to keep your boat clean and free from dirt, water, snow, leaves or bird droppings, all of which can cause damage if left unchecked plus a complete cleaning job next spring. A cover can also prevent UV rays from paint fading, cracking carpets & upholstery plus giving longevity to the thin plexiglas windows in a thse curtains if applicable. Support the cover with a framework to distribute the weight of any water or snow that may accumulate.

Batteries : You may want to leave a battery aboard your boat to operate a automatic bilge pump or possibly a burglar alarm. These are both useful in the winter, but don't expect an automatic pump to overcome bad deck, cabin, or hull leaks. The bilge pump, battery, or float switch can fail, leaving the boat unprotected. A boat with chronic leaking problems should be dry stored and repaired as soon as possible. If you do leave a battery aboard, make sure the cells are filled with distilled water and fully charged so they don't freeze. Frozen cells will ruin a battery. Clean the terminals with baking soda, and rinse with cold water. Coat the terminals and cables with Vaseline to help prevent rust. If you don’t need a battery aboard, take it home and do all of the above anyway. Store batteries in a cool dry room and put them on a trickle charger or charge them every 30 to 60 days.

Go thru your storage & remove anything that may have crawled in & hid during the summer. If you are like me, I like to be prepared, however there may be a time when some of that stuff you thought may be important is just excess baggage & needs to be considered being left in the towing vehicle or at home. Any excess weight removed may increase your boat's maneuverability & also the fuel economy.

Fresh Water System : Completely drain the fresh water tank and hot water heater. Isolate the hot water heater by disconnecting the in and out lines and connecting them together. Pump a non-toxic antifreeze into the system and turn on all the faucets, including the shower and any wash-down areas until you see the antifreeze coming out. Put non-toxic antifreeze in the water heater.

Head : Pump out the holding tank at an approved facility. While pumping, add fresh water to the bowl and flush several times. Use Vanish crystals or whatever your owner's manual recommends that will not harm your system and let it sit for a few minutes. Add fresh water and pump out again. Add RV antifreeze and pump through hoses, holding tank, Y-valve, macerator and discharge hose. Check your owner's manual to make sure that an alcohol-based antifreeze won't damage your system. If you happen to have a Port-A-Potty aboard, remember to tend to business with it & drain the water from the holding tank.

Bilge : Clean the bilge. Check the function of the bilge pump & any automatic float switches controlling it. Make sure the bilge is clean and dry. Use soap, hot water and a stiff brush to clean up any oil spills. Once the bilge is clean, spray with a moisture displacing lubricant and add a little antifreeze to prevent any water that may accumulate from freezing.

Ventilate Closed Areas: If you have a aluminum boat that has under a splash well battery/storage, if it has a door closure, it may be best to see that this door is open. The reason is that aluminum may change with the winter weather temperature & then if the door is closed, have condensation inside. There will more than likely also be a lot of wiring there. Moisture for a long period of time & electrical wires are not compatible. This would also apply to under the bow storage compartments to air out anything stored there.

In-Water Storage For Moored Boats : Be sure that all the seacocks are closed & check rudder shafts and stuffing boxes for leaks, then tighten or repack as necessary. Check any thru the hull fitting & correct any leak if found. Check your battery to make sure it is fully charged, clean the terminals, add water if necessary and make sure your charging system is working. Check the bilge pumps to ensure they are working, that the float switches properly activate the pumps, and that they are not hindered by debris in the bilge. Make sure to check your boat periodically or have the marina check it and report to you. Check with the marina, some require a signed letter from you allowing them to board your boat even in an emergency, (been there-done that).

Trailer Winterization : Look at the tires for any checks, bulges, or uneven tread wear. Rotate or replace any looking bad. Now is the time to look at the wheel bearings also & trailer brakes if you have them. CLICK HERE for a link to this repair.

If you have the older leaf spring type & use the unit in salt water, the springs WILL become RUSTY. Now may be the time to pull them off, have them sandblasted & coat them with a CRC brand product called Heavy Duty Corrosion Inhibitor. This stuff comes in a 16 oz. spray can, so is very easy to apply. It never really hardens, possibly to 95%. If the metal is rust free, it will do wonders in protecting metal, even in salt water. You probably should also replace the bolts holding these springs to the axle & the the end linkages while you are at it. Or you could wire wheel the bolts & nuts, paint them with a aluminum spray paint to extend their life.

Check the trailer lights & all connections. Look at the light for the license plate, does it function? Straighten a bent license plate. Repair or replace any side clearance lights.

Check your trailer rollers for cracking & the hog rings/retainer washers on the roller shafts. Check the carpeted bunk padding for tears if you have that kind. Now might be the time to add a polypropylene covering to your carpeted bunks.

Check the trailer winch, & cable or strap for wear. If the winch has been attacked by a tad of rustitis, sandblast & repaint it. If it is an electric model, remove the battery & place it inside so that you can check & maintain a full charge over the winter. Also the check tie-down straps, chafe pads & safety chain.

Grease the tongue jack stand internal gears & telescoping tubes.

Summary : All in all, anything you can do in the slack winter months will extend your time next year when the boating season rolls around & you will not be setting on the shore waiting for a set of back-ordered wheel bearings from 1000 miles away or a seized gearbox on the motor when everyone else is enjoying the water. Or worse, stuck along the road somewhere near TimBucToo in the middle of a vacation with a problem you should have caught months before. Have a safe & happy boating season next year.

Think about this, if you still work for a living, think of the following: How many free days a year do you have? Of those how many are available for fun (spelled boating/fishing)? Of these how many will the weather cooperate, and finally, of these will your motor/boat run correctly or will you spend half the day tinkering with it or waste a major chunk of your vacation?

Spring Startup : Do your normal starting the motor. It will smoke excessively, so if you have close neighbors, warn them so they do not call the fire department. Let it run for 10 minutes or so warming up & to be sure things are OK for your upcoming fishing season.

Observation : When shutting off a motor if it is to be stored even for a few weeks as compared to winterization, if the engine has only one carburetor, it's unlikely that running the engine out of gas would do any harm.   When the single carburetor runs out of the fuel/oil mixture, the engine just stops running.

However, an engine that has more than one carburetor should simply be shut off leaving fuel in the carburetors.   The reasoning is that the top carburetor will run out of fuel first due to gravity and the engine will continue to run on because of the still existing fuel in the other lower carburetors.

This results in having at least one aluminum piston running up and down a steel cylinder wall with improper or no lubrication.   You might sneak by for a while if you make a practice of this.   But not a good idea!   It may be best to occasionally start this motor using muffs & run it a while to warm things up & replace what fuel is in the carburetor.

Back to OMC Info Back to Ramblings

Originally started 11-09-2009, Last Updated 09-30-2011
to contact the author click here