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  1. #1

    Default 2017 Mondo - No RAW Water Flow Question

    Quick question: with the water impeller out of the housing and the cover plate off, should water, via a garden hose connected to the inlet on the bottom of the boat, push water into the impeller housing with or without the engine running? I'm getting nothing - no flow.

    I thought maybe the impeller was toast but I pulled it out and it's fine... well not any longer now that I pulled it out but it was fine

    Not so great day on the lake yesterday - if you can even call it that. Boat started smoking and then overheating as soon as we got past the no wake zone after leaving the dock. I saw 235 degrees at some point.
    2017 Moomba Mondo Surf Edition

  2. #2
    Join Date
    Jan 2021
    Location
    Columbus, Ohio
    Posts
    1,360

    Default

    Check the ball valve on the thru-hull where the water is sucked in. If some how it got closed you will overheat quickly.

    The water inlet is the lowest point in the system and the hose would have to push past the v-drive and transmission before water would be in the raw water pump. Follow your lines from thru hull up to pump.

    A clog will cause this also. Most likely the heat exchanger. Remember if you are clogged upstream you cannot push the air out of the system to get fresh water in. 235 is scary but if that is all you got to, you should have avoided damage.
    2015 Moomba Mojo Surf Edition
    4,000lbs
    Manual Flow

  3. #3

    Default

    I see. Thanks. I just assumed the hose from the thru-hull pick up/inlet went directly to the water pump.

    I noticed the ball valve handle when looking through the v-drive access hatch. It's currently oriented to be in line with the hose and doesn't look to have been touched, ever. I'm assuming it's in the open position in its current state.

    When testing to see if water flows, I started the engine and it ran perfectly fine (only ran it for less than 30 seconds) but still no water getting to the pump housing from the garden hose via the under hull pick up/inlet.
    2017 Moomba Mondo Surf Edition

  4. #4
    Join Date
    Jan 2021
    Location
    Columbus, Ohio
    Posts
    1,360

    Default

    The pump has to draw water through the v-drive first. It takes a minute before coming out of the exhaust.

    Are youbgetting water in the bilge? Missing or loose plug would cause some issues also.
    2015 Moomba Mojo Surf Edition
    4,000lbs
    Manual Flow

  5. #5

    Default

    Got it. I was hoping the water pressure from the garden hose (using a fake a lake) would push water through the system and come out of the pump housing since I had pulled the cover and impeller. Instead, the water was just spraying along the bottom of the hull where the fake a lake meets the hull. I didn't see any water in the bilge area.

    Ideas on the next steps? Start pulling hoses to see what I find?

    Where does the heat exchanger fall into the mix? I assume it's also cooling oil so I would need to make sure I am pulling the correct hoses.
    2017 Moomba Mondo Surf Edition

  6. #6
    Join Date
    Sep 2005
    Location
    Claytor Lake, VA
    Posts
    604

    Default

    Where does the heat exchanger fall into the mix?
    Follow the large hose leaving the V-drive and the next thing it connects is the transmission heat exchanger. Pull the hose off and use your finger to clean out any debris.
    2005 Mobius LSV
    325 EFI

  7. #7
    Join Date
    Mar 2021
    Location
    South Georgia
    Posts
    2,065

    Default

    Can you try backwashing from the raw water pump with the hose. It may blow any clog out if it's not too far into the inlet on the bottom of the boat. But you may have to be creative with the connection to make that work.

    Sent from my SM-G781V using Tapatalk
    2021 Moomba Makai
    Black Cherry Metal Flake & Fire Red
    Nibral OJ 15.5x15 Altitude/Wake prop w/1.76 trans v-drive
    Wet Sounds bow speakers & 10's on the Tower & ported sub

  8. #8
    Join Date
    Jan 2021
    Location
    Columbus, Ohio
    Posts
    1,360

    Default

    VA LSV is correct.

    Just follow hoses up.
    Thru hull to v-drive
    V-drive to Trans
    Trans under engine to raw water pump.
    Water pump to coolant heat exchanger - canister on starboard side of raw water pump

    Canister to exhaust manifolds

    The u-pipe under the pump is a low spot that can catch debris also. There is a blue plug in this pipe to pull and check for water.

    Also, you can pull the water flow sensor out and check for a clog there. It has a key ring on it and is tight to get out.
    2015 Moomba Mojo Surf Edition
    4,000lbs
    Manual Flow

  9. #9

    Default

    Thanks, all. I appreciate the quick responses. I'll poke around some more and start following the lines and see what I can flush out... right after it's not 100 degrees and 95% humidity.
    2017 Moomba Mondo Surf Edition

  10. #10
    Join Date
    Mar 2021
    Location
    South Georgia
    Posts
    2,065

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    If you are anywhere around me you will be waiting a while for that to happen! A cool low humidity day that is! LOL!

    Sent from my SM-G781V using Tapatalk
    2021 Moomba Makai
    Black Cherry Metal Flake & Fire Red
    Nibral OJ 15.5x15 Altitude/Wake prop w/1.76 trans v-drive
    Wet Sounds bow speakers & 10's on the Tower & ported sub

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