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How To Winterize Your Boat: Part 2

Maintenance & Repair > How To Winterize Your Boat: Part 2

Winterization of an outboard doesn't have to be hard and there isn’t Voodoo involved.  Here are some things to keep the innards and outtards of the engine in good shape during winter lay-up.

Lower Unit

Lower Unit - Before draining the lower unit, set the engine, or trim it, to an upright position and let it set for a few minutes.  This would give any water or debris that may be in the gear case a chance to settle to the bottom.

Put a clean container under the gear case to catch the used gear lube in.  Loosen and remove the drain and vent plugs.   Drain the contents of the gear case into the pan.  Inspect the gear lube for water (milky looking oil or just water coming out) and traces of metal.  Sometimes if the gear lube hasn't been changed for a while, it will be very black and really stink, like a burned smell.   Good used lube will have a darker color and be free of water and debris.

If water is found in the gear case, a pressure/vacuum test can be used to determine what seal(s) are leaking.  (Note:  At my shop, all winterizing includes the press/vacuum test.  These are simple tests to do.  Pressure test, apply 12 to 15psi of air to the gear case and let stand for 15 minutes while periodically rotating the shafts and shifting gears.  If the pressure doesn't decrease, go to the vacuum test.   Pull a vacuum of 12 to 15"hg on the gear case and let stand for 15 minutes again rotating the shafts periodically.   If vacuum doesn't decrease, the seals can be considered good.)

Any metal found in the gear case should be investigated and any repairs made before the engine is run again.

Replace the vent and drain plug washers (or o-rings) with new ones.

If all is found well with the lube, refill the gear case with fresh lube.  Fill from the bottom up until the lube runs out the vent hole.  Fill slowly so any air in the gear case will vent out.  Spinning the prop while filling can help this.

When full, replace the vent plug first, then replace the drain plug and tighten.

Pull the prop off.  Clean the prop shaft splines and remove any string that may be wrapped around the shaft.  Clean the splines in the prop.  Apply a coat of a marine rated grease to the prop shaft and re-install the prop.  Tighten the prop nut to manufacturers specs.


Fuel:  Top off fuel tanks or cans and add stabilizer to the tanks according to the instructions on the stabilizer container.   Full tanks helps to lessen condensation and water build up in the fuel during the lay-up period.   This should be done before engine is run for fogging.


De-Carb:  Before actually fogging the engine, now would be a good time to do a de-carb.  De-carbing the engine keeps the rings free, helps keep carbon build up to a minimum and generally adds to the longevity of the engine.  

De-carbonizing an engine is a simple process where in an agent, produced for the de-carb process, is introduced into the engine while it is running and up to temperature.   The engine is then allowed to soak for a specified time with the agent inside.   Afterwards, the engine is started and lose carbon is blown out the exhaust.

There are several products on the market for the de-carb process so be sure to read the directions on the product container and follow them.


Fogging the Engine:  The whole idea of fogging is to coat the inside of the engine with a heavy lubricant to protect the ferrous metal against oxidation and keep the moving parts lubricated during the lay-up period.   Fogging is done with the engine running for good dispersal of the fogging product through the engine.

Be sure to read the directions on the fogging oil container. 

Fogging can be done with the engine in the water or with flushettes  (muffs) attached to the engines lower unit.  For the salt water folks, if no fresh water is available to back the engine into, use flushettes and fresh water from a garden hose to prevent salt build up in the cooling water passages of the engine.

Basic procedure to fog, start the engine and allow the engine to come up to normal temp at idle.  This will also allow the treated gas to circulate through the fuel system.  Once the engine is warm, inject the fogging oil through the carb throats. ( NOTE:  some engines are equipped with a special attachment for fogging)   Inject the fogging oil equally into each carb.  The idle may have to be adjusted up while injecting the fogging oil to keep the engine from stalling.  Once the correct amount of fogging oil has been injected, let the engine stall and shut off the key if engine is a remote start.  Remove the spark plugs and shoot some fogging oil directly into the cylinders.  Rotate the flywheel clockwise by hand to coat the cylinders.   Clean or replace the spark plugs and install, torque to specs.  Wipe out the lower engine pan with a shop rag and replace the engine cover.

After fogging, you are basically done with the engine internals.  Use a quality marine grease to lube the grease fittings on the engine according to the manufactures guidelines.  Also, another good, often missed idea, is to clean the steering cable ram and apply a light coat of grease to the surface of the steering ram.

Now would be a good time to clean the outside of the engine and apply a coat of your favorite marine polish.   This will protect the engines finish during lay-up.

Disconnect the battery(s) once the boat is in its lay-up position.   If the boat and motor is stored outside, store the engine in the vertical position to prevent rain and snow from building up in the exhaust area right behind the prop.

Store batteries in a cool area.  Top of the electrolyte with distilled water if needed.  A small trickle charging system can be used to keep the batteries in good shape for the lay-up period and fully charged for use in the next season.

Article Credits:
Article put together by Forum Moderator Jim Doughty, Kenneth B. Sanderson, and others.

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