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  1. #1
    Petty Officer 2nd Class
    Join Date
    Jun 2005

    Default How to winterize 50 HP mercury four stroke

    What needs to be done with a 1999 Mercury 50 HP to wnterize it? I know the basics like drain the block of all water and change the oil in the lower unit and motor.I was wondering if there are any specific things that should be done so I dont regret it next year.

  2. #2
    Rear Admiral Plainsman's Avatar
    Join Date
    Apr 2006
    From the panhandle of Nebraska

    Default Re: How to winterize 50 HP mercury four stroke

    Rest in Peace Spinner

    2010 Lowe FM 175 with a 2010 115 Mercury
    Your friend,your partner, your defender,your dog.You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such E.F. Henry

  3. #3
    Supreme Mariner
    Join Date
    Mar 2004
    On Barnegat Bay, NJ

    Default Re: How to winterize 50 HP mercury four stroke

    Jake, I did not read the entire post by Eric (too long). Outboards are self-draining, so I recommend the following.

    Fill the tank with gas and the appropriate amount of fuel stabilizer. Remove the propeller, and either store separately, or grease the prop shaft and reinstall at the end of the winterization process.

    Start the motor on the muffs, and run it for 5 minutes or so to flush it. Spray fogging oil into the carb intakes until it smokes a lot or stalls. Turn off the ignition

    Remove the muffs and let it drain in a vertical position for 10 minutes.

    Drain and refill the engine oil and filter. Drain and refill the gearcase oil.

    Spray powerhead with corrosion protection. Pump marine grease into all the grease fittings you can find.

    Leave the motor in a vertical position if at all possible Disconnect battery.

    I do not belive in putting plastic bags on the LU or powerhead. I think it traps moisture. A canvas or duck cover on the powerhead is good to keep the sun off of it.

  4. #4
    Petty Officer 3rd Class
    Join Date
    Oct 2002
    Charlevoix, MI

    Default Re: How to winterize 50 HP mercury four stroke


    I have a 2001 50 hp 4stroke. ditto to above except I was told by both the service tech I bought it from and from the Mercury service line to NOT fog this motor. Something about the motor not running hot enough to burn the fogging oil away soon enough to prevent the exhaust valves from overheating. I just change the oil and filter and grease everything with zircs. I always add stabil to the fuel to prevent problems. I run it on muffs for a few minutes after changing the motor oil to insure fresh oil is run through the engine. I then follow the Merc recommendation and add a little motor oil to each cylinder and slowly turn the motor over a couple of times by hand (with the spark plugs removed) to spread the oil around the cylinders.


  5. #5
    Seaman Apprentice
    Join Date
    Sep 2006

    Default Re: How to winterize 50 HP mercury four stroke


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