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  1. #1

    Symptoms of Loose Impeller?

    I have a 900 ZXI and the last time i was out (last fall) everything was running good with it, but I went wide open with the throttle from sitting still and the engine revved all the way up and the ski didn't get on plane and hardly moved. It sounded/felt like a car doing a burn out. From then on it would not get on plane and would only do about 10-15 mph @ 4-5k rpms.

    I found some swelling on the wear ring from corrosion behind it and the impeller was just starting to scrape the top of some of the bumps. I'm in the middle of replacing it. I am waiting on the new wear ring. Fortunately it doesn't appear much damage was done to the edges of the impeller, but there is some light pitting from cavitation on the fins.

    Further, when I went to remove the impeller, I found it was only hand tight and was backed off the threads about a quarter of the way. In addition, when the ski was running on the trailer, it had a rattling noise that came from the jet pump area. I know these things are supposed to be noisy on the trailer so I assumed it was normal. It has done that since I got the ski, but I have only owned it for about a year and have only been out a couple of times. My question is: could the rattling noise on the trailer and the lack of power be due to the impeller backing off that much or is there something bigger I should look at before I just replace the wear ring and put it back together? What kind of symptoms does a loose impeller show?

    Also, the tolerances are within spec. I have 0.4mm clear (limit is 0.6mm) between impeller and old wear ring (will remeasure with new). Bearings and seals seem good. No water leaking in. Stator fins look excellent.

    Thanks in advance for any insight.


  2. #2
    1200 stx-r's Avatar
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    Did u check threads on shaft and impeller prior to reinstalling with impeller tool? Def should not be ANY clanging or banging in or out of water. If that was loose I would def check out all nuts/bolts / clamps on machine . U never know what someone thought they did right.....

  3. #3
    I haven't reinstalled it yet. This is the first time I have had this pump apart, but to answer your question: yes, i have looked at the threads and the splines on the drive shaft and inside the impeller and both are fine. No signs of sheared teeth. The impeller tool fits nicely in the splines.

  4. #4
    Myself's Avatar
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    Yes, sounds like a loose impeller to me. Use blue threadlocker on it and get it VERY tight.

  5. #5
    Thanks Myself. Good to have a little confirmation before it goes back together.

    Since Kawi does not make a replacement wear ring for this jet pump, I had to either buy a new pump or get one of those made ones. I went with the made one, which is basically a piece of thin stainless sheetmetal wrapped in a circle and welded. Not too crazy that it isn't continuous all the way around, but I think it will work. I'm going to J.B. Weld over the bead on the inside surface of the weld and then sand it down to get a nice smooth surface.


    I put some nonhardening sealant on the wall of the housing to help prevent the corrosion from building up again. I then pressed the new ring in and now there is about a 0.5 mm gap between the wear ring and the housing behind the weld. The metal ring appears to get a little thinner on the back side just along the welded area. I know I have heard of people having gaps behind the rings with other skis that have replaceable rings. Any suggestions on how to seal it up?

  6. #6
    Myself's Avatar
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    Run some silicone gasket maker along both ends of the new ring . Maybe that will totally seal the back side of it from the water.

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