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  1. #1
    Resident electronics hacker UnityRacing's Avatar
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    Pump rebuild, spacer not correct? Eating bearings!

    A few years back (prior to parking the project) I had rebuilt my pump with a new set of bearings and seals, and an NuJet 7.0 impeller.
    Within 45 minutes of ride time, the bearings self destructed and seized up. Ok I thought, cheap rebuild kit is to blame. Upon inspection of the failed parts I found that the center collar/spacer between the 2 bearings seemed a tad long. If I held it in the stator and lined up either end, it was about 1mm longer than the bearing seat surface. This was the root cause of the failure for sure, as I could see where the spacer was dug into the bearings.

    Fast forward to today, I just received a known good quality rebuild kit from Watcon, and ordered brand new from a Polaris dealer the stub shaft, and both the spacer and seal collar.
    I am comparing the old spacer to the new one, and both are the same length, even this new one is about 1mm too long to sit flush with both bearing seating surfaces.

    So - with all that said, whats the deal here? Has anyone else run into this? Am I not supposed to seat the bearings fully in the stator? Everything I have ever known about bearing installs is they are supposed to be seated from the outer race, and typically flush, but this just isn't going to happen with what I have.

    Also, what exactly gets greased? Do I pack the inner area between the spacer and the stator? Just the tail cone?

    Thanks in advance!


  2. #2
    Resident electronics hacker UnityRacing's Avatar
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    BTW - this is a SS 6 vane stator from either a 99 Genesis or an 02 Txi (Thought they were the same) that's going on an 02 TXi.
    Spacer part #'s ordered were 5010294 and 5134505

  3. #3
    Resident electronics hacker UnityRacing's Avatar
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    Hmmmm - this thread is EXACTLY the problem I have. And my stator looks clean, nothing shaved off, no spun bearings, etc.

    http://www.greenhulk.net/forums/showthread.php?t=54360

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by UnityRacing View Post
    Hmmmm - this thread is EXACTLY the problem I have. And my stator looks clean, nothing shaved off, no spun bearings, etc.

    http://www.greenhulk.net/forums/showthread.php?t=54360
    I suppose it is possible your stator was incorrectly machined from the factory.

    A machine shop should be able to determine whether a spacer washer is needed behind one or both bearings to get them correctly positioned. And confirm the alignment between the bearings is correct.

  5. #5
    Resident electronics hacker UnityRacing's Avatar
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    On that link I posted, posts 11 and 13 are what I'm getting. I find it hard to believe that they were machined incorrectly from the factory :/

    What I might do is install the bearings so they are sort of floating a tad from the bottom seat surface and see what that nets me. In the end, its the lateral force being applied from squishing the impeller down and clamping the inner races to the spacer. Realistically it shouldn't matter if the outers are seated on the "shelf" below them. Unless I'm missing something obvious, the bearings are only to allow the impeller to spin freely with no side to side play. The big thing is just making sure they are square in the hole.

    Worth a shot anyway.

  6. #6
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by UnityRacing View Post
    ... it shouldn't matter if the outers are seated on the "shelf" below them. Unless I'm missing something obvious, the bearings are only to allow the impeller to spin freely with no side to side play. The big thing is just making sure they are square in the hole...
    There is a factor you are overlooking.

    100% of the thrust from the impeller is transferred to the watercraft via those two bearings on the stub shaft. The impeller is doing all it can to pull itself forward in the water. It pulls on the stub shaft, which is prevented from moving forward only by the rear bearing in the stator housing, and the front bearing which is held in place by the friction fit.

    So those two bearings together experience a lot of forward thrust. Side load on the bearings, in effect.

  7. #7
    Resident electronics hacker UnityRacing's Avatar
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    I agree that the rearward bearing should be fully seated, but the forward bearing should not be experiencing the effects of the thrust. Basically both bearings and spacer are getting clamped together, and so long as the side load force is being seated I think it will be fine. I just find it real hard to believe that only 2 people have had this issue, and it's blamed on faulty manufacturing. Now what I could believe is Polaris had a different part number for the early 6 vein stators, that was never really "put out there".
    I have another stock pump unit that is working fine, but I am reluctant to take it apart for fear of the same situation. At least I have a spare, and i've gotten to the point I can swap them in 5 minutes.

    Worth a shot...

    Not trying to argue or anything, but there has to be another solution besides replace it or take to a machine shop (the ones here are few and pricey, everyone does the large jobs working for the shipyards, they don't want to touch little crap)

  8. #8
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    There were 2 different versions of the 6 vane stator. The first ones were made by Skat Trak and the later ones were made by Asia Trend. I don't think there were any physical differences between them though

  9. #9
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    Where did you source the bearings from? Is it possible that the issue is the physical size of the bearings being used and not the stator itself? We have seen issues with SBT crank bearings being slightly thicker than OEM, I wonder if we are dealing with the same sort of thing here.

  10. #10
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    Quote Originally Posted by UnityRacing View Post
    I agree that the rearward bearing should be fully seated, but the forward bearing should not be experiencing the effects of the thrust. Basically both bearings and spacer are getting clamped together, and so long as the side load force is being seated I think it will be fine. I just find it real hard to believe that only 2 people have had this issue, and it's blamed on faulty manufacturing.
    Worth a shot...
    I also ran into this problem and believe the bearing failed from hammering in the second bearing.
    I used the "thermal" installation method and it has been working good-no trouble.

    I put the bearings and stub shaft in the freezer, warmed the stator, left the spacer at room temp.
    Assembled with impeller to tighten inner races/spacer. Made sure to push the rear bearing to it's seat. Left all of it to cool/warm to room temp, then installed the seals.

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