How to Winterize an OMC Stern Drive Boat

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Snow and ice are the enemies of fresh-water-cooled engines and their accompanying outdrives, so winterization of OMC stern drive boats is a must for owners who live in climates where water freezes. Winterizing all stern drives is not an extremely complicated process. In some cases, extra precautions may require a little extra time, but it’s all worthwhile when the boat starts up the next spring without a hitch and ready for a summer of fun.

Items you will need

  • Soapy water

  • Sacrificial anodes

  • Prop wrench

  • Screwdriver

  • Engine grease

  • 80-grit sandpaper

  • Sheets

  • Painter's tape

  • Aerosol primer

  • Aerosol engine paint

Step 1

Clean all external marine algae or barnacles from your outdrive with a stiff brush and mildly soapy water. Check for corrosion and inspect the sacrificial anodes for wear. If the anodes are more than 50 percent eroded, replace them with fresh pieces. There are five to look for: one on each of the hydraulic lifts on the sides of the stern drive; one on the rear -- toward the boat -- underneath the lip of the casing; one on the front -- away from the boat -- underneath the lip of the casing above the prop; and one underneath the prop that you can check when you take off the prop.

Step 2

Use the pointed end of a prop wrench to lift the prop tabs in the locking ring, and then turn the wrench over and use the wrench end on the prop nut at the center of the hub. Twist and remove. Take off the prop tab, the locking ring and the prop. Remove the prop washer from underneath the prop and remember what direction it was facing because you must be put it back in the same position. Check the prop anode while you have the prop assembly off the hub. Replace the anode if necessary.

Step 3

Remove the lower plug from the rear bottom of the unit with a screwdriver to drain the oil. Use the screwdriver to remove the fill plug from the top of the unit for a pressure release that will let the fluid move quicker.

Step 4

Check the drained oil for any sign of water, including water balls in the oil or milky looking oil. Check for metal flakes in the oil. Replace the oil by inserting the nozzle of an outdrive oil bottle into the bottom drain plug. Do not simply pour oil into the top. The connections to the lower casing do not allow for back flow and the oil will not get into the bottom. It will go up to the top if pushed in from below. Plug in the lower drain and close up the top when you see oil emerging from the top hole.

Step 5

Inspect the rubber boot connections between the hull and the stern drive for cracks.

Step 6

Check the exterior surface of the outdrive for missing paint or signs of corrosion. Sand the corroded areas with 80-grit sandpaper until they are smooth. Protect the hull and any other surface you do not want painted with a sheet and some painter's tape. Use an aerosol version of underwater primer that is designed to prime aluminum. Allow the primer to cure -- usually 18 to 24 hours -- then paint with an aerosol prop and drive paint. This will help prevent further corrosion and possible damage to the drive.

Step 7

Grease the fittings and check fluid levels for lift pumps.

Step 8

Apply a generous amount of grease to the prop hub and replace the prop by reversing the process for removing it.