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8.1 Overheating quickly

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  • 8.1 Overheating quickly

    Replaced impeller in my 8.1 GI-J 3 months ago. It sat until Saturday. It overheated within 5 - 10 minutes of cold start. Do I replace the T Stat? Any help is appreciated

  • #2
    First welcome aboard

    when you pulled the old impeller, was any of the vanes missing?

    when you replaced the raw water pump, did you mix the hoses up at the raw water pump?

    did you check for water flow?
    Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

    1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

    Past Boats
    1970 Wooster Hellion - Merc 9.8
    2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
    1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

    What’s behind you doesn’t matter.Enzo Ferrari

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    • #3
      Old impeller was not visibly bad, just had 200 hours on it. The boat ran fine the 2 times we had it out prior to parking it in the garage for the winter. I changed it since I had just bought the boat.It then say for 3 months until Saturday, only other thing I can think of is I installed with the fins going the wrong way.

      Hose diameters are different, so while it is possible it would be hard to get them swapped.
      I will be looking at that one more time before I install the replacement for the replacement impeller.
      I want to replace it since it got hot. It got hot enough the alarm sounded. So I always side on safe than sorry.
      Just not sure if a T stat is in order or not.

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      • #4
        I don't think you have enough information to isolate the overheating to the thermostat. You could remove it and put it in a pot of water heating on the stove to see at which temperature the thermostat opens (meat thermometer or similar)

        If the t-stat starts to open at the prescribed temperature, then it is working properly.
        Best regards, Ted . . . . Cape Cod, MA

        Current Boats: Formula 330 Sun Sport, O'Day Mariner Sail #3224, Sunfish
        Past Boats: Catalina 22 Sail #10531, Formula 242 Sun Sport
        Twin Mercruiser 7.4 LX MPI (0F802036, 039), Bravo 3's (0F806198, 199), Mercury 7.5 HP (1969), Johnson 4.5 HP (1980)

        My Boating Web Pages: http://www.tpenfield.com

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        • #5
          The vanes would flip themselves

          Pull the impeller and look to make sure the new impeller is in good shape and not burned up
          Cheesehead boating the Gulf Coast of FLA 27.51° N, 82.53° W

          1988 Cruisers Rogue 2420 -VP 290 DP now powered by custom 468 - https://forums.iboats.com/forum/owner...988-rogue-2420

          Past Boats
          1970 Wooster Hellion - Merc 9.8
          2002 SeaRay 190BR - 5.0 - A1G2 - "Cheeseheads in Paradise"
          1984 Avanti 170DLI -3.0 stringer- "Ship Happens"

          What’s behind you doesn’t matter.Enzo Ferrari

          Comment


          • #6
            Had the same problem once. Turned out I had two rubber O rings installed and was not getting a good seal, sucking air. Make sure that you only have one pump O ring installed and that it is positioned correctly.
            Summer Fling-II
            2008 Chaparral Sunesta 264
            Summer Fling
            2003 Chaparral Sunesta 243

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            • #7
              Sign up today
              It was suggested to me yesterday at the boat store while picking up a new impeller - again, to be sure the blue cap on the hose connection is tight. if air is sucked in it can cause an O/H condition.
              Thanks to all that provided guidance. I will install and check things out later this afternoon.

              Comment

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