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Long Winter’s Nap


Protect, maintain, and drain your outboard before putting it to bed so it will be raring to go come spring.

Neglecting your outboard over winter could be an expensive mistake come spring.

Well before winter’s cold arrives, your outboard needs to be prepared — especially if you live where freezing could occur (more places than most people think). You can do it yourself with hand tools, an afternoon’s time, and some pretty inexpensive supplies. You’ll need a place to work, where you can start and run the engine(s) for a short while without incurring complaints about the noise and (some) smoke, a good water supply, and adequate ventilation. While winterizing procedures vary somewhat for older engines vs. newer ones, and for two-stroke vs. four-stroke outboards, the basics are the same. To do the job right, you need to protect, maintain, and drain.

Protect Your Machinery

Consult your engine’s owner’s manual or service manual before you begin. Today’s engines (especially four-stroke and direct-injected two-stroke outboards) may have special winterizing, flushing, and maintenance instructions, so follow them closely. For example, Evinrude’s E-Tec outboards feature a self-winterizing mode in the engine’s electronic programming. What a great feature — it’s simple to do by following the instructions in the winterizing section of the owner’s manual, yet if you don’t know about it, you might be tempted to try it the traditional way. If your engine is still under warranty, and you don’t winterize it according to the manufacturer’s instructions, you could easily void the warranty coverage.

While the specific instructions might vary, in most cases, you’ll need to do the following:

  • The engine’s fuel supply must be treated for storage or drained completely. For a discussion of expert opinions, see “The Ethanol Debate.”
  • The engine should be flushed according to the manufacturer’s instructions. Sometimes, this doesn’t involve running the engine at all; newer engines have a garden hose fitting that allows for a quick flush without starting the engine. Check your manual for specifics.
Check your owner’s manual for the correct winter flushing technique for your engine. (Photo: John Tiger)
  • The engine’s lubricants (engine oil for four-stroke outboards, and lower unit gear lube for all outboards) should be drained and refilled, and the fuel filters changed. Water or other contaminants must be flushed out and replaced with fresh lube before winter. Any water present in the gearcase, for example, will sit on steel shafts and bearings over the winter, coating them with rust. Run the engine to get the oil and lower unit lubricant warm before draining. This will make it flow easier and also get any contaminants in suspension so they drain instead of sitting inside. Change the oil filter when you change the oil. Change the fuel filter. If your engine doesn’t have a water-separating fuel filter, consider installing one now.
  • After treating the fuel and running the engine for a few minutes, the engine should be “fogged” with a storage lubricant. This protects the internals (bearings, seals, and rotating surfaces) with a thin film of lubricant, which helps keep rust and corrosion away. With the engine running, inject fogging oil through the carburetors or electronic fuel injection (EFI) system air intakes in such a way as to “flood” the engine with oil until it begins to smoke, then continue fogging it until it stalls. Fogging can also be done with the engine shut down; in this case, the spark plugs are removed and the oil is sprayed into the cylinders, rotating the flywheel to distribute the oil.

Perform Periodic And Routine Maintenance

Check your owner’s manual and have all periodic maintenance done. Much of this will be beyond the expertise of the average do-it-yourselfer — valve adjustments, belt tension adjustments, etc. — and must be done by a qualified technician. Perform all necessary repairs, or at least put them on the list for spring. Then take the opportunity to complete routine maintenance so there aren’t any surprises next year. That includes the following:

  • Pay particular attention to gearcase damage. If the propeller is damaged, have it repaired now, not in spring. You may even get an “off season” discount. Check the blades, and look for cracks — especially on stainless steel props. Small cracks can quickly spread and grow, and sometime next season you may find yourself short a blade. When you remove the prop, rotate the propeller shaft to check for damage. Check for fishline snarls around the forward thrust washer (the one between the forward end of the prop and the rearward end of the gearcase). If there’s fishline there, check the lube carefully when you drain the gear case. Snarled fishline often damages the seals in the gearcase’s rear bearing carrier. This lets lubricant out and water in. If there’s water present in the lubricant, it will be milky-appearing and a light coffee color, and the gearcase must be resealed.
  • Check for electrolysis corrosion on the lower unit, propeller, and any surrounding metal, and repair it. Electrolysis appears as small white crystals of fine powder attached to the prop, gearcase, and other metal surfaces. It occurs as a reaction to dissimilar metals or electrical current in the water. To repair the lower unit, sand corrosion off, clean, and paint with primer and then factory-matched paint. While automotive primer will work, it’s better to use a marine primer with zinc chromate to help further retard corrosion. This is also a good time to replace the anodes.
  • Lightly lubricate all moving parts with a fine silicone lube. This includes throttle and shift linkages, tilt pins, and steering shafts.
  • Check the manual for greasing points, and grease them with a marine (preferably synthetic) water-resistant grease. Typically, these greasing points are at pivot areas: steering, tilt, trim, engine cowl latches, etc. Don’t over-grease; the excess typically hardens over time and clogs up the works. Grease the propeller shaft before reinstalling the propeller.
  • Lubricate the steering system. Steering cable systems also need to be greased (there is typically a grease fitting at the engine end of the cable). To keep old grease from building up and hardening inside the cable, it’s best to remove the cable from the engine, then rotate the steering wheel so the cable is fully extended. Clean all old grease from inside the cable end, then lightly coat the inner cable shaft with fresh synthetic marine grease. Reattach the cable to the engine and rotate the steering lock-to-lock a few times to distribute the new grease. If your steering system is hydraulic, check the fluid level and free play in the system. If fluid level is low, top it off with fresh hydraulic steering fluid, and then, if necessary, bleed the system to purge excess air.
  • The engine trim system should be checked carefully for leaks. The fluid level should be topped off with the correct fluid. Coat the electrical connections lightly with silicone lubricant.
  • Inspection and maintenance of a performance outboard rig equipped with a jack plate is safety-critical. Check the engine and jack plate mounting bolts for tightness, as well as the up/down movement and any side-to-side free play. Look carefully for cracks in the plate; if any exist, replace the plate — don’t attempt to fix it.
  • Clean out water pressure gauges and/or a speedometer that uses water pressure. Consider removing the gauge pressure hose and using compressed air, blowing any remaining water out of the hose and fittings. Removing the hose from the backside of the gauge will allow any water to drain out of the gauge itself, reducing the chance of freezing damage.
  • If your boat will be stored out of the water, remove the batteries and store them in a cool, dry place. Clean the terminals; use a trickle charger to keep them charged during the winter.

Drain All Water

After all this is done, all water should be drained from the engine and drive to eliminate the chance of freezing. If there’s water in the engine block or in the gearcase and it freezes, chances are high it will crack the surrounding material, which is an expensive repair bill for you. Most outboards can be drained simply by tilting them to the upright, running position. Allow all the water to drain from the powerhead through the propeller and/or exhaust outlets. Store the engine in the running (tilted down) position; otherwise water that gets in through the hub can freeze and crack the lower unit housing.

Protect From The Elements

All the painted, exposed surfaces of the outboard should be protected with a coat of wax. The engine should be covered with a fabric or plastic cover that can be secured tightly enough to keep it from flapping and abrading the paint. After it drains, the exhaust opening should be covered with plastic tape and sealed to keep water and rodents out.

Properly winterizing your outboard engine will assure that your engine — and you — will be able to nap comfortably during the cold months ahead and hit the water running at the first sign of warm weather.

John Tiger

Contributor, BoatUS Magazine