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  1. #1
    Richieb's Avatar
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    Impeller has all the tips of the blades heated up and worn away.

    Ok all you Polaris experts... here's one for you.

    The Impeller on a 2000 1200 triple has all the tips of the blades heated up and worn away, what is the cause of this?

    The bearings and seals are all new, and perfectly aligned.


  2. #2
    Click avatar for tech links/info, donation request K447's Avatar
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    Which model of 2000 Polaris?

    Can you post some clear photos of this?

    When you say tips, do you mean the outside perimeter of the impeller blades, or the blade leading edges?

    What is the clearance to the wear ring around the impeller?
    What condition is the wear ring inside surface (smooth, grooved)?

    Without seeing the photos, my first suspicion is cavitation damage.

  3. #3
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Cavatation was thing I thought of too.

    Pics would help Richie.

  4. #4
    Richieb's Avatar
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    Hi, many thanks for the reply.

    The Ski is a STX 1200 2000 model 135 HP.

    The damage is around the perimeter edge of the blades.

    The one thing is that the edges appear to be turned over by about 1/2mm with a sharp edge. There is a usual working gap between the impeller blades and the Ring, not too big, and definately not touching the blades as they rotate.

    This is a friends Ski we are trying to fix. We changed out all the bearings, seals and stub shaft following it collecting a piece of rope in there. I have fitted them absolutely perfect. The bearing shaft ran freely in the housing, and was tensioned with th impeller in place, and it all ran smoothly.

    We had the ski out on the river a few times,... probably about 7 hrs in total. The ski suddenly made a strange noise and the speed dropped right off, we brought it to shore, and after taking the pump off, found the stub shaft had sheared at the start of the threaded point, and left the rest of the thread in the impeller.... obviously wrecking the seals, and allowing salt water into the bearings.

    The reason I went straight to open up the pump was to see if we could note the problem before salt water got to it all.

    The bearing(sealed ones) which seemed strange to me in the first place, were of the sealed type, which makes it difficult to pack them with water-proof grease. Is this the case for replacement bearings.. Should they be a sealed type, or open type?

    Anyway, the bearings looked good, and showed no sign of over-heating or stress, and neither did the stup shaft. The only odd thing was the perimeter edge of the impeller. It has very sharp turned back edges, and is dis-coloured by what appears to be friction heating, yet the impellerhas not visibly had any contact with the ring. I did put a new prop in at the time of the re-build, and there was a gap about 1/2 mm all round, and it turned smoothly without catching anywhere.

    I will see my friend this evening, and will get some shots of the impeller perimeter edges.

    Cheers,

  5. #5
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by Richieb View Post
    ...STX 1200 2000 model 135 HP.

    The damage is around the perimeter edge of the blades.

    The one thing is that the edges appear to be turned over by about 1/2mm with a sharp edge. There is a usual working gap between the impeller blades and the Ring, not too big, and definitely not touching the blades as they rotate.

    This is a friends Ski we are trying to fix. We changed out all the bearings, seals and stub shaft following it collecting a piece of rope in there. I have fitted them absolutely perfect. The bearing shaft ran freely in the housing, and was tensioned with the impeller in place, and it all ran smoothly.

    We had the ski out on the river a few times,... probably about 7 hrs in total. The ski suddenly made a strange noise and the speed dropped right off, we brought it to shore, and after taking the pump off, found the stub shaft had sheared at the start of the threaded point, and left the rest of the thread in the impeller.... obviously wrecking the seals, and allowing salt water into the bearings.

    The reason I went straight to open up the pump was to see if we could note the problem before salt water got to it all.

    The bearing(sealed ones) which seemed strange to me in the first place, were of the sealed type, which makes it difficult to pack them with water-proof grease. Is this the case for replacement bearings.. Should they be a sealed type, or open type?

    Anyway, the bearings looked good, and showed no sign of over-heating or stress, and neither did the stup shaft. The only odd thing was the perimeter edge of the impeller. It has very sharp turned back edges, and is dis-coloured by what appears to be friction heating, yet the impeller has not visibly had any contact with the ring. I did put a new prop in at the time of the re-build, and there was a gap about 1/2 mm all round, and it turned smoothly without catching anywhere.

    I will see my friend this evening, and will get some shots of the impeller perimeter edges.
    That would be a Polaris SLX 1200, not STX, I expect

    If the outer edges of the impeller are sharpened as you describe, then the impeller was probably rubbing the wear ring. Maximum allowed clearance between blades and wear ring is 0.020 inches (0.5mm), and under 0.010 inches is preferred (0.25mm or less).

    When the jet pump was re-assembled, is it possible that the pump sections were not 100% mated, possibly due to corrosion build-up where each section mates to the next?
    Were the four long pump bolts still tight when the pump was pulled off?

    If the jet pump was not aligned with the engine and drive shaft, it could put stress on the impeller bearings and stub shaft.

    Is it possible the replacement bearings in the jet pump stator were not 100% seated and aligned?

  6. #6
    AWA Member 32DegH2O's Avatar
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    Was the drive shaft checked to make sure it didn't become bowed after the rope incident? Or make sure the drive coupler didn't become bent and that the rubber donut in the couple was intacked?

  7. #7
    Richieb's Avatar
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    Ok, here we go, Photos Galore..... eventually......
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  8. #8
    Richieb's Avatar
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    Oh, and are the bearings I got supposed to be of the sealed type?, according to the dealer , they are the kit as it should be, but my thoughts were 'How do I pack them with WP Grease then?

  9. #9

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    That stub shaft is missing some of the threads they must have snapped off . The wearing is from it rubbing the spacer . you need a new prop and stub shaft to start post some pics of the spacer .

  10. #10
    Richieb's Avatar
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    Yea, I have the rest of the threaded part out of the prop, it had snapped/sheared.
    I concur with the Rubbing on the wear-ring, but what caused it, and are the bearings the right ones?

    I have some Hi-res photos, bt as they are 2.XXMb in size, I cant seem to upload them... any ideas on this?

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