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  1. #1

    Cannot figure out how water is getting into the hull, any thoughts?

    1994 Polaris SL750


    1. Hook up garden hose to fitting, water pours down from intake grate and out from rear nozzle. Nothing gets into the hull.
    2. In the water, on the trailer, fire it up, rev it, no hoses leaking or seals leaking.
    3. Sit on the water with seat removed, no water trickling in from anywhere so no holes in the hull.
    4. OEM Siphon hoses properly secured, routed, and clean.
    5. Out on the water, zooming along, lots of water in the hull.
    The bilge pump is plenty to overcome and keep dry, but I MUST keep running if on the water. The siphon hoses either don't work, or are not enough. I am worried that a failure in the bilge will strand me with a quickly-filling ski someday, so I want to figure this one out.

    My thoughts are:
    1. The intake/jet pump assembly is pressurized while underway, and this pressure is forcing water into the hull. OK, but where? And what to check/redo/seal to stop it?
    2. There is a hole on the drivers/left side of the hull slightly forward of the handlebars and below the waterline. It is a fitting, and is obviously there to discharge water. Is it possible that this only discharges water at speed? And perhaps it is disconnected somehow and discharging into the hull? And if so, why is the hole not leaking when on the water? And what is this hole for anyway?
    3. The hull has aged to a point where the fiberglass allows water molecules to pass at speeds above 30 mph. (a stretch I know)
    4. Magic invisible unicorns are peeing in the hull when I go too fast. (seriously, I am out of ideas here)
    5. At speed, water is splashing up, getting under the seat, and filling the hull because some seal is missing. (grasping at straws)


  2. #2
    BlueFishCrisis's Avatar
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    I'd go with #4.

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  4. #3
    BlueFishCrisis's Avatar
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    If there is a hole on the side of the ski, below the waterline, it should be for a bilge pump. Look for a hose connected there. Where does your bilge currently discharge?? Does your MFD work? Is the pickup tube in the pump tunnel connected to a line? Is the line broken or cut somewhere between the fitting and the MFD. The line pressure here increases while riding, and may not leak while sitting. Do you "submarine" the nose alot while riding? If you don't have the front storage bucket in, and / or the seals are in bad condition, water can enter there. Are the footwells badly cracked under the hydroturf? Fill those areas up while sitting to see if they are leaking. You can try filling the ski up with water while on the trailer and see if the leak reveals itself that way....

  5. #4
    This is how I run a jetski shop in the desert nmpeter's Avatar
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    it IS #4, and the unicorns got into the hull from the speedometer feed tube ( called a pitot) about the size of a battery vent line it has a hole someplace ( clue #1 is no speedo reading on the water)

    When the ski is moving the pitot tube is pressurized which is why these don't show up on the trailer (or in the tank for that matter)

    Easy test:

    with the hull having a couple of inches of water in it, pressurize ( 2-3 psi is all you need..or a friend with big lungs) the hose leading to the console watch for bubbles inside the hull under the driveshaft

    the actual pitot can be found under the driveshaft. The part can be found on this page:

    http://www.bikebandit.com/houseofmot...8477#sch486696

    DO NOT pull on that tube, the plastic gets brittle and snaps like a pringle.

    Most likely the hose can be spliced, battery acid has likely eaten it thru.

  6. #5
    auto culto's Avatar
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    Or you can do what I have just done and accidently leave your flush tap open and sink it

  7. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    The early Polaris watercraft had a drain fitting on the side of the hull which drains ingested splash water from the air intake snorkel, which is located just under the handlebar mechanism (rough memory).

    Make sure the hose on the inside of that side hull fitting is actually connected at both ends.

    Ride with the seat off and watch for water entry.

    One possibility is the seals where the drive shaft exits through the hull. If those through-hull shaft seals are worn then water will force itself forward along the drive shaft at speed and dibble or spew out under the drive shaft inside the hull.

  8. #7
    The hole on the left side is connected to a rather large rubber hose that runs to the front of the engine somewhere, something to do with the exhaust is my suspicion. I will trace it later, but it is dry and does not seem to be leaking.

    The speedo tube is connected and is working, so I can't image there is a leak there.

    I am thinking the driveshaft seal. I will have to see how the seal works and if it is compromised.

    Sadly, the bilge pump crapped out while riding today, so I have to deal with that since I can't stop the water form getting in. The bilge exit just under the seat, just behind my right leg BTW.

  9. #8
    UPDATE:

    Was on the water this weekend with a new Bilge pump. Did some repairs to the bottom of the hull to seal up some gouges from rock impacts. Nothing serious, but good preventative measure. Noticing less water in the hull, so that is good, but still getting some. The thing is, the water coming out is leaving black soot on the ski. It is slightly warmer than the river water, but not much. Watching when it is coming in, I have a theory.

    It seems like water is getting into the exhaust and then into the hull. It's not in there very long, because it isn't hot, but it has to be the exhaust because of the soot. I am thinking that it is coming in from the exhaust outlet at the back of the ski, and then into the hull through a leak. I am going to pull everything and check it out, but that is the updated theory.

    With the bilge, I can keep the hull pretty dry, so I enjoyed a nice long day on the water. A run back to the dock at sunset made me remember why I work on this thing in the driveway.

  10. #9
    David Drkvampire2001's Avatar
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    get a good flashlight, strap it to the trailer, front and rear, back it into the water and turn it on, no fear of burning anything up and it gets water running threw th emotor, now look over every exhaust connection! could be a gasket at the cyls leak, could be leaking where the pipe attaches to manifold, or where the pipe attaches to water box or where water box tube attaches to go to the exit in the back fo the ski. if you see no leaks accelerate get some preassure behind it and see

  11. #10
    David Drkvampire2001's Avatar
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    Quote Originally Posted by BlueFishCrisis View Post
    If there is a hole on the side of the ski, below the waterline, it should be for a bilge pump.
    just saw this Blue. i have had this same question on my 94 SL 650, there is a hole in the side of the ski below the water line, BUT NO bilge is on the ski. i have been unable to figure out what its for, my 650 leaks no water but the water routing comes in from the rear of the ski for teh engine and such so i have not a clue what its for. but its for sure not a bilge

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