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  1. #1

    Join Date
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    1100 STX unkown leak

    Hey guys, I'm a long-time lurker but never needed to register until now. I have a leak that just developed last year, and I can't seem to locate it! I've had this ski for about 8-10 years and it has been pretty much flawless in operation until this leak recently.

    First off, it's not at the driveshaft bearing/seal, so that's out (I watched it like a hawk). I ran it for 15 minutes or so this week on a local river with the seat off, and it will fill up to about the motor mounts in that 15-20 minutes of riding. Now, if I am not running the engine, the leak still occurs but is much slower to fill. There is nothing spraying into the engine compartment, and it doesn't leak AT ALL when running out of the water on the hose.

    Yesterday, I tried the reverse-fill method of finding the leak, and it held water (filled to just over the motor mounts) with not a drip for 10 minutes. Side note: I noticed some bubbling coming from the starboard motor mount near the carb when I was watching for the leak, but I didn't see any significant amount of water anywhere. I don't know how water would enter from under the motor mount anyway as there aren't any major hull cracks, but a few places with gelcoat chipped. I'm stumped! Also, the self-sump system must not be working too well, so I'll need to figure out how to troubleshoot that, too, as the mechanism under the back seat has had the infamous Kawasaki green glue come un-bonded from the hull.

    Thanks in advance for any help!


  2. #2

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    The bubbling from the mount concerns me. If it is leaking from the mount, the only thing that would explain it leaking more with the engine running is the vibration causing movement in a crack that might be there. I would think it is leaking from a cooling line hose.

  3. #3

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    Quote Originally Posted by keithg1964 View Post
    The bubbling from the mount concerns me. If it is leaking from the mount, the only thing that would explain it leaking more with the engine running is the vibration causing movement in a crack that might be there. I would think it is leaking from a cooling line hose.
    Well, I would be inclined to agree except that it runs for several minutes on the trailer (garden hose connected) with no water anywhere. Possible that the water pressure through the flush kit isn't enough to cause the leak? Possibly something that gets worse as the ski moves faster? I didn't have a flashlight handy at the time and obviously no inspection mirror either, so getting at the back of the ski behind the battery/waterbox was impossible, as was looking under the engine.

  4. #4

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    Running on a hose is reverse flowing compared to normal operation. There may be more pressure running in water as compared to on an hose. I would get some hose pitching pliers and pitch the hoses going to the pump and apply about 10 pounds of air pressure to the flush connection. That or connect the hose turn on the hose until you get a little pressure and shut off the hose.

  5. #5
    ImpactSportsTV's Avatar
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    I have (2) '97 STX1100 skis that both had the same problem - it was the plastic through-hull tube fitting for the engine cooling water from the jet pump that was the problem. The way I narrowed it down was by connecting a garden hose to the outside of the hull (next to the jet pump) via a hose reducer, and disconnecting and plugging the cooling line at the engine/exhaust fitting (I can't remember which it is off the top of my head). You then send pressurized water through the fitting - in my case water was spraying very heavily from various voids in the hull bulkhead. I know it sounds far fetched, but that is what it was. The cause is that there is a 3/16" thick plate of aluminum that is built into the bulkhead. this plate internally separates slightly from the rest of the construction which causes a shear point that causes a crack in the plastic tube.

    I fixed mine by replacing the white plastic through hull fitting with an aluminum one, and it has been great ever since. R&D makes one like I used (for a 1/2" hose fitting). R&D part # is RD660-00012
    best of luck!
    W
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  6. #6

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    Quote Originally Posted by ImpactSportsTV View Post
    . . . You then send pressurized water through the fitting - in my case water was spraying very heavily from various voids in the hull bulkhead. I know it sounds far fetched, but that is what it was. The cause is that there is a 3/16" thick plate of aluminum that is built into the bulkhead. this plate internally separates slightly from the rest of the construction which causes a shear point that causes a crack in the plastic tube . . . W
    Is the bulkhead you are referring to located fore or aft of the driveshaft seal? That seems pretty plausible if that ends up being my issue. At the very least, I can drag it back to the ramp and check it there instead of having to pull off the intake grate and source out the hose reducers. My ski doesn't run out of the water too well due to what I imagine is a lean-runaway after a 30 seconds to a minute of running. I have the fuel primer kit on there, so I'd imagine the carb gasket or lack of choke butterflies is the culprit. She starts/runs fantastic when it's on the water though, so I leave it be.

  7. #7
    ImpactSportsTV's Avatar
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    Aft - it is the white plastic through-hull fitting on the port side of the jet pump.

  8. #8

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    I appreciate the info, I'll drop it back into the water some time this week with a flashlight and inspection mirror. This will give me a couple places to focus on. I'll follow up with what I find just to help anyone else who searches this problem later on.

  9. #9
    ImpactSportsTV's Avatar
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    Best of luck! FYI, water trickled into mine when it was just sitting in the water, but was much worse when under power as the leak is then under pressure - food for thought.

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