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5.0L GL-B Cooling issues

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  • 5.0L GL-B Cooling issues

    I'm having a problem with my boat not picking up raw water either in the water or on muffs. I did a complete raw water pump rebuild with a kit I ordered off amazon. The install went smooth but it overheated when I took it out the first time. I brought it home and started trouble shooting.

    I put the muffs on and removed the inlet pump hose and had water to the pump. I removed the outlet and started the engine and no water. I know it must be something with the water pump, is it possible that I got a bad impeller? The few videos I've seen the impeller had to be soaked in soap water and even then it was a tight fit. Mine seemed to slide in without any effort. Wrong size impeller and not priming maybe?

    I bought the boat used and have taken it out twice with no over heat problems. The original owner couldn't tell me when he replaced the impeller last so I figured I'd replace it for peace of mind. The impeller I pulled out was a VP stamped impeller, this one in the kit was not.

  • #2
    Did you have the hoses reversed?

    Did you back flush?
    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


    • #3
      The impeller is a tight fit but soaking in soapy water shouldn't be needed.
      The cheap aftermarket ones, the brass insert can break loose and the impeller not turn.
      Take it apart and place the new on top of the old.
      You should be able to tell if it's the same size??

      Inspect the area around the insert for spinning insert.

      Check the hose/ coupler on the drive.

      Buy American made Cars and Trucks!!!Towing insurance for a boat,a GREAT thing.
      ​Tools to make my life easier: Battery tester, die grinder, temp.gun, compression tester, DVA meter.

      In Scenic , Beautiful San Sebastian by the sea Florida

      88 Bayliner 21CC 2001 Mercury 225 HP EFI



      • #4
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        I removed the one I purchased and put the VP impeller back in. No more cooling issues. The impeller I ordered was the same diameter but the VP impeller was about an 1/8th of an inch thicker.

        I ordered an OEM VP impeller. Lessons learned!