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  1. #1

    Slt 780 pump issue

    New owner off 780 ran great all last year
    This season was out at lake and heard something wasn't right then seen impeller was loose so tore it apart Click image for larger version. 

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ID:	397515 that's what I found. I have another 780 in my yard I got for parts so took the pump off of it and rebuilt it I followed instructions per manual during rebuild when i assembled it the impeller wouldn't spin freely me not knowing if this was normal or not I put it on and 20 mins out on the lake destroyed the bearings same result as old ones any clue to what I did wrong?


  2. #2
    Guessing the bearings were bad. I just made one ski out of two as well They should spin inside the stator

  3. #3
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by azdesertjunkie View Post
    New owner off 780 ran great all last year
    This season was out at lake and heard something wasn't right then seen impeller was loose so tore it apart Click image for larger version. 

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Views:	38 
Size:	405.7 KB 
ID:	397514Click image for larger version. 

Name:	IMG_1402.JPG 
Views:	37 
Size:	305.9 KB 
ID:	397515 that's what I found. I have another 780 in my yard I got for parts so took the pump off of it and rebuilt it I followed instructions per manual during rebuild when i assembled it the impeller wouldn't spin freely me not knowing if this was normal or not I put it on and 20 mins out on the lake destroyed the bearings same result as old ones any clue to what I did wrong?
    Perhaps the newly installed bearings were not fully seated in the stator hub or the internal spacer was missing or no longer the correct length.

    It is critical that the bearing installation in the jet pump rebuild be 'perfect'. Even a minor 'binding' in the impeller rotation must be corrected as the new bearings will not last long otherwise.

    What manual instructions were you following? OEM Polaris service manual or a third party repair manual?

  4. #4
    Oem Polaris manual I found online i had the internal spacer not sure if it was correct length. When you get the impeller torqued on is it saposed to spin freely or should it be hard to turn by hand? Thanks for the reply

  5. #5
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by azdesertjunkie View Post
    ... internal spacer not sure if it was correct length.

    When you get the impeller torqued on is it saposed to spin freely or should it be hard to turn by hand? Thanks for the reply
    The spacer length can be measured.

    In addition to the length the spacer needs to not be mushroomed at either end. Both ends must be square and clean. Any visible damage means the spacer is likely out of spec and should be replaced.

    I have posted videos of the jet pump, you should be able to spin it with a couple of fingers. No binding, no gritty or grinding feeling or noises.




  6. #6
    Ok yeah I probably need a new spacer then mine didn't turn that easy. Any other suggestions? Don't want to keep having to rebuild it hopefully this time I'll get it right

  7. #7
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by azdesertjunkie View Post
    Ok yeah I probably need a new spacer then mine didn't turn that easy. Any other suggestions? Don't want to keep having to rebuild it hopefully this time I'll get it right
    The bearings must be fully seated inside the stator hub. Did you use the oven and freezer method to install the bearings?

    The hub interior must have zero dirt or grit prior to bearing install, and the inside surfaces must be smooth and the bottom shoulder (that the installed bearing will sit against) must be flat, withno chewed up areas.

    After the bearings have been installed with the spacer in between, a good self check is how much slop there is between the spacer and the bearings. The spacer should slide sideways behind the bearings with just a little surface friction, yet there should be almost zero end to end play for the installed spacer.

  8. #8
    Yeah I did the oven and freezer way and I'll clean it up really good before I put new ones in is there a certain measurement to tell the bearings are all the way in or just if they won't go down anymore there good

  9. #9
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by azdesertjunkie View Post
    Yeah I did the oven and freezer way and I'll clean it up really good before I put new ones in is there a certain measurement to tell the bearings are all the way in or just if they won't go down anymore there good
    You can measure the depth of the stator cavity on each side, then subtract the width of the bearing outer race. When installed that would be how far down the seated bearing should sit. And be evenly seated all the way around.

    I sometimes use a bearing tool to tap on the just dropped in cold bearing, to ensure it is fully seated against the shoulder below.

    If you want to use a bearing tool it must be sized to install a 52mm bearing.

    The pressed in jet pump seals are 55mm OD diameter but the actual tool size is a couple of mm smaller so it can fit inside the outer rim of the seal. I don't have that size on hand at the moment

  10. #10
    I tapped mine into place a lil with a big socket that I had in my tool box but I think my friend has the actual tool I'll give it a try

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