Winterizing Older OMC Two-Stroke Outboards

by James W. Hebert

In northern climates most outboard motors are not used from October to May. Preparing a motor for a long period of non-use like this is called "winterizing." A brief guideline for the proper procedure to prepare an older two-stroke motor for a long lay-up period is presented below. These instructions are based on recommendations from the master marine mechanics at LOCKEMAN'S HARDWARE AND BOATS, one of the oldest sellers and service providers of Outboard Marine Corporation's (OMC) EVINRUDE and JOHNSON brand outboard motors in the world. To their sage advice I have added some further explanations and notations. The specific products mentioned are Bombardier Recreational Product's (BRP) EVINRUDE/JOHNSON branded products. There are similar products made by most all outboard manufacturers, as well as generic and after-market brands, which can be used.

Purchase Check List

In addition to the typical hand tools needed, before beginning the lay-up procedure you should have on hand the following materials:

Winterizing Procedure

To prepare the engine for a long period of non-use, perform the following procedure:

  1. Add fuel conditioner to the fuel tank. Consult the label on the fuel conditioner for the recommended proportions. When adding the fuel conditioner to an internal tank with a long filler hose, it is a good idea to follow up with some additional gasoline in order to flush the additive from the filler hose and assure it is introduced to the tank. In the case of large internal tanks, it is a good idea to provide some agitation to the tank to insure good mixing. The easiest way to do this is to put the boat into motion, either on the water or on the trailer. Small portable tanks can be mixed directly and agitated by hand.
  2. Remove propeller from shaft. Engines being run on a hose attachment should always have the propeller removed to avoid any potential for contact with a moving propeller. It is also a good practice to remove the propeller at least once a season to prevent it from corroding in place on the shaft. Apply marine grease to the shaft. Be sure to remove the thrust washer. See your owner's manual for details. Install the hose attachment and supply it with the appropriate flow of water.
  3. Run engine. The engine should be run at fast idle speeds for at least 15 minutes. This warms up the engine and insures that the treated fuel has circulated into the entire fuel system. Large displacement engines will consume fuel rapidly. Smaller engines may have to be run longer to insure that the treated fuel has been circulated. This is particularly true if there are large volume filter canisters in the fuel system. A water separator filter can hold enough gasoline to run a small engine for quite a while. When you are certain the treated fuel has been circulated throughout the engine, shut it off.
  4. Induce fogging oil. On many OMC engines there is a Schrader valve fitting in the fuel system which allows direct attachment of the fogging oil canister. If your engine has this handy device, attach the hose from the fogging oil to the Schrader valve. If you engine does not have the Schrader valve fitting, you will most likely have to remove the air silencer cover to expose the carburetor throttle bodies. With the fogging oil either in hand or connected to the Schrader valve, re-start the engine and set it to fast idle. Induce the fogging oil into the carburetors (via the valve or by spraying it into the throttle bodies). CAUTION: If spraying into the throttle bodies be careful to not allow the plastic spray tube to be ingested into the motor! CAUTION: If using a Schrader valve attachment, be certain to return the fuel primer valve to the closed (clockwise) position after removing the fogging oil attachment; this valve may be inadvertently opened by the turning of the attachment as it is removed. Continue inducing fogging oil until the engine exhaust smokes excessively. (One can is sufficient for a V6 engine.) As the fogging continues the engine may eventually stall. Do not restart. If the engine does not completely stall out, shut off the engine when a small volume of fogging oil remains (about 1/10 of a can). Shut off hose and remove hose attachment.
  5. Remove spark plugs. Spray a generous amount of fogging oil directly into the cylinders via the spark plug holes. By hand, rotate the engine flywheel clockwise to change the piston position and spread oil to cylinder walls. Inspect spark plugs. Clean and re-gap the existing plugs if serviceable, or install new plugs. (I recommend installing the new plugs in the spring, after the engine has been returned to service and the fogging oil has been burned off.) Consult the owner's manual for instructions on how to index the spark plug position as required on some direct-injection motors.
  6. Change gear case lubricant. Allow all water to drain from the lower unit of the engine. Tilt the engine fully up, allow the water to drain, then lower engine to fully down, and again allow water to drain. Remove the two drain screws from the lower unit and allow the lubricant to drain. Inspect the drain screws for proper gaskets or o-ring seals. Inspect the seats of the drain screws for debris from old seals or o-rings. If the head of the screw is mutilated, replace with new screws. NOTE: the new BRP drain screws have a hex insert for better grip instead of a flat-blade screwdriver slot. They also have newer style nylon washers to replace the older o-ring style seal. Inspect the the removed lubricant for signs of water intrusion. Generally if water is emulsified in the lubricant it gives it a milky appearance. If any sign of water is noted, the gear case should be pressure tested for leaks and repaired if necessary. Re-fill the gear case with the proper lubricant and to the proper level. Re-install drain screws.
  7. Clear speedometer pickup. If your engine has a speedometer pickup tube on the lower unit it should be blown clear of any water with moderate air pressure (less than 25-PSI).
  8. Lubricate all grease fittings. A small grease gun will be useful to add grease to all areas of the motor with Zerk fittings. The tilt tube and tiller tube areas must be greased to prevent corrosion, particularly in boats used in saltwater. Grease the steering ram, as well as other areas on the motor as directed by the owner's manual or factory service manual.
  9. Wipe down the engine block and inside of cowling. Clean any accumulated spills of fuel and oil. Spray engine block with protective coating such as BOESHIELD T-9 or OMC/BRP D.P.L (Dries, Protects, Lubricates) Install cowling. Clean and wax cowling. Spray tilt and trim mechanism.

Storage Fuel Mixture

The OMC factory service manual recommends preparation of a small 6-gallon tank of fuel for use in winterization. The tank is prepared as follows:

Run the engine for five minutes on this storage mixture fuel at 1,500-RPM This procedure is often used in service shops. One six gallon tank of this storage mixture can be used to prepare many engines for storage.

DISCLAIMER: This information is believed to be accurate but there is no guarantee. We do our best!

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Copyright © 2005 by James W. Hebert. Unauthorized reproduction prohibited!

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Author: James W. Hebert
This article first appeared November 20, 2005.