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  1. #1
    AZFlats's Avatar
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    Hello from AZ new member here- looking for a little help

    So I just purchased a pair of Polaris slt780 (1996) skis and a 1993 seadoo. Got em cheap. I have always owned boats, but never had a Pwc. Soooo, here I am! Excited to learn and help based on my experiences with these 3 new projects.

    So, Seller said all three worked fine, but they have not been running and have been sitting in the AZ sun for 6 years. I started with the first Polaris. tested compression, 140-150 on all the cylinders.
    Pulled the engine, pump and everything else stuffed in this little hull to clean all the grease, oil, rat crap and nests out.
    Cleaned the engine, crank shaft was filled with oil. (I guess the oil pump let oil leak in through while sitting?) drained it and cleaned the inside through the carb ports.
    Carbs were rebuilt,
    oil pump removed, blocked off the port.
    Cylinder walls look great, pistons have good wash
    resealed the top end, popped it back in the hull. Everything else is in now and I started work on the jet pump.

    First off, the kit I ordered through amazon, did not come with the big fat o ring that fits on the drive shaft, (prop side). And one of the bearing seals was 2mm too large for the stator opening, (nose cone side). (Had to get both of these locally)
    anyways, got it all back together, but now the nose cone is not fitting. Is there supposed to be a gasket before the cone? I tried to torque it down with the three screws, now it seems I stripped the threads in the aluminum. (Damn). I think if there was a gasket here, the cone should fit snugly. I had about a 32nd of an inch gap before I could not go down any further.
    Any advise for a newbie? hopefully I will be getting her wet real soon.
    Thanks- Andy.


  2. #2
    Moderator HiPeRcO's Avatar
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    Welcome to GH! You've come to the right place for Polaris help

    I can't answer your specific questions about that particular pump area, but a good place to start (and a good resource) is the Polaris parts diagrams, they can be found here: http://parts.polarisind.com/Browse/Browse.asp

    And my signature has a link to a lot of useful Polaris info.

  3. #3
    AZFlats's Avatar
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    Thanks! I have looked through this schematic before. It does not show what's between the nose cone and the stator....

  4. #4
    Moderator HiPeRcO's Avatar
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    Quote Originally Posted by AZFlats View Post
    Thanks! I have looked through this schematic before. It does not show what's between the nose cone and the stator....
    It would seem if its not shown, then its not there

  5. #5
    No gasket, just a o-ring. It should be #17 under propulsion on polaris diaghram. Tail cone bolt torque 72 in ibs.

  6. #6
    Click avatar for tech links/info K447's Avatar
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    Welcome

    The jet pump stator has a tail cone that seals the back end of the hub bearing cavity (tail cone points out the rear of the jet pump nozzle when installed).

    On some Polaris watercraft the impeller nose has a small tapered rubber seal where the driveshaft enters the impeller. Some guys call this a nose cone for the impeller.

    Other impellers instead have a thick o-ring near the driveshaft end which is inserted inside the snout of the impeller and seals from the inside. These two driveshaft to impeller sealing methods are specific to the impeller and are not interchangeable.

    Polaris had an oddball 'twisted' tail cone on a few 780 models from that era. It was shaped with an angle and may have used longer screws to attach it to the stator. If you have the longer screws but are installing the 'regular' tail cone then the screws may have bottomed in the holes without clamping the tail cone snugly in place.

    The water seal for the tail cone is a single o-ring seated into an internal groove inside the stator hub. That o-ring must be in place and must be in good condition. Also the tail cone must not have hairline cracks or damage where it fits into the o-ring. Waterproof grease prior to assembly is helpful for the o-ring seal.

    If your model and year originally had the twisted tail cone (check my signature links to confirm) a popular upgrade is to install a six vane stainless steel stator in place of the factory five vane aluminum stator. The SS stator is a better stator and does not need the twisted tail cone, the regular tail cone works well.

    In later years Polaris added a flat rubber gasket between the stator and the tail cone flat mating surface. This flat gasket can be retrofitted to the earlier model year modular jet pumps. It is not expensive but the three screws must not be overtoghtened to avoid squeeze out of the thin rubber material. The large o-ring inside the stator is still the primary water seal.

  7. #7
    casey67's Avatar
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    Quote Originally Posted by AZFlats View Post
    And one of the bearing seals was 2mm too large for the stator opening, (nose cone side). (Had to get both of these locally)
    Both of the seals go into the front of the pump (impeller side).Alot more going on, on this side.

    No seal on the cone side. (not as much pressure on this side I guess).Just the o-ring-some, people put a small amount of silicone on the cone to seal against the pump.

  8. #8
    AZFlats's Avatar
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    Holy crap, so no bearing seal on the cone side? That explains why the cone did not fit there and left a gap.. So, both seals go in on the front side of the stator? Or, do I just use one of the two seals that comes in the kit?

  9. #9
    ripcuda's Avatar
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    Correct... both seals go on the forward side of the jet pump stator where the shaft is sticking out (that impeller threads on). There is no shaft exiting the rear so no seal needed. It's fully capped off by the tail cone. Have you disassembled both Polaris jet pumps? If not... look at the one still together and see how it all goes together.

    As for the large o-ring on the end of the driveshaft that goes into the impeller... it's there to help reduce rattling and to help minimize water getting in there and washing away the grease you put on the driveshaft/impeller splines. It's not uber critical and I've reused these fat o-rings without issue. Just pull the pump a time or two during the season for inspection and put more grease on the splines.

    Cheers!

  10. #10
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by AZFlats View Post
    Holy crap, so no bearing seal on the cone side? That explains why the cone did not fit there and left a gap.. So, both seals go in on the front side of the stator? ...
    Those are shaft seals. The pre-greased bearings are sealed, but I dunno what a separate bearing seal might be

    Two shaft seals are fitted to the front side of the impeller hub, directly in front of the front bearing. Make sure the bearings are fully seated and each seal is correctly oriented when installing them.

    See my signature link or search on here for the freezer+oven method of installing the bearings.

    When the stub shaft is inserted from the rear it clamps the rear bearing inner race, the spacer that fits between the two bearings (this part is critical) and the front bearing. In front of the front bearing is a shorter spacer that actually fits inside the front seal inner lips. Grease those inner seal lips before inserting the front spacer.

    When the impeller is screwed onto the stub shaft and torqued the entire inner assembly is clamped tightly together and rotates as a single unit. This is why it is critical that both bearings be properly seated and the inner spacer be correct length and not causing any binding in the bearings.

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