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1990 25hp Mercury water pump replacement

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  • 1990 25hp Mercury water pump replacement

    I told my neighbor I could replace his water pump that failed on his outboard. I can't believe how hard it is to find which parts are for this outboard. I usually work on Johnsons.
    His serial # is C258397. Model number is 1025312j. He hasn't replaced it in 20 years. All that was left was a nub.
    I don't need a total kit. I need the impeller, gaskets, O-rings and the rubber piece the water tube goes into.
    Any help would be greatly appreciated.

  • #2
    Re: 1990 25hp Mercury water pump replacement

    Originally posted by MNmarty View Post
    All that was left was a nub.

    Uh oh..that's not the kinda news you wanna here. If you're looking for a good way to kill your motor then don't replace your impeller. Better have him do a compression check on that guy if he only had a nub left. The good thing for you is that it's not your boat. Could get expensive. Iboats has the impeller kit you are looking for tho with part #18-3215. However, this kit does not include the water pump inlet tube, so you will have to purchase this separately. They have this as well tho under part #18-3109. Good luck to you both!


    • #3
      Re: 1990 25hp Mercury water pump replacement

      Thanks. That sierra kit looks like the gasket I took out. What had me all messed up is the catalog says the 18-3427 kit is the replacement for that serial number. Those gaskets looked nothing like the one in the outboard.
      I hear ya about compression. I don't have a gauge to check it. I've already taken the lower unit off and the kit is only around $20. I might as well replace the water pump and put it back together. It's an outboard on his pontoon that he uses to take the evening booze cruise. Might not even notice if the power is low. He may have really screwed it up though. The motor was sizzling when it died!
      Thanks again for looking up the numbers.


      • #4
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        Re: 1990 25hp Mercury water pump replacement

        I am also trying to replace the water pump on my 1990 25hp mariner but I can't get my lower unit off. I can't figure out how to get the gear shifter unattached. Please help.