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  1. #1

    Join Date
    Mar 2008
    Milwaukee, WI

    Question torn rubber impeller seal causing cavitation???

    I have a 2008 STX 15f and it got some weeds sucked up into it and after that it wasn't taking off as fast as it should or having the top end speed like it should. After putting it on the trailer I noticed that there's a rubber piece (it's on the shaft tight to front edge of impeller)on the front side of the impeller that has a tear in it. Could this be what's causing the lack in take off acceleration and top speed I had before? Would this be covered under warranty? The pump housing and everything else appears to be normal and I've never ran it in shallow water so I can't say it's caused from gravel or sand. So my questions are,
    1: is this what is causing the lack in acceleration/top end speed (I still can get 50mph or slightly higher out of it but it lags a bit more to get there than usual)
    2: will this ruin anything if I run it like this until I can get it into a shop or buy a replacement part
    3: I looked online and it's only a $3 part (part #92093 on rivamotorsports oem parts finder), would this be something I could replace myself if it wouldnt' be covered by warranty?
    4: if it isn't covered by warranty, would it work better or worse if I'd cut it off and go without it
    Thank you for any and all help

  2. #2
    That's a shaft seal to keep water out of the aft drive shaft splines-it has nothing to do with cavitation. You should replace it when you have time and apply fresh grease to the splines and seal after cleaning the old stuff out.

    Buy a couple of the seals cause they need routine replacement. It's easy to replace, pull the ride plate and pump then pull the seal from the impeller front end. It takes an hour or so to do.


  3. #3
    nicjak's Avatar
    Join Date
    Mar 2008
    Warragul, Downunder
    if it is infact torn and flapping about it is possible to cause cavitation, just tear it out or cut the broken piece out it is ok to run without it but replace it when you get the chance. very common to tear out.

  4. #4
    I wouldn't tear it out, it's possible it is still sealing water out and only the edge portion is ripped. Mine was ripped for half a season with no ill effects. Cavitation is caused by the ingress of air and large debris in the pump intake. The seal is too small to cause this effect. Then again, it is possible to be struck by la bolt of lightning

    Actually it is quite simple, if the machine runs fine or the same as usual with no cavitation why not leave it be until replacement time?


  5. #5
    Offshore Aussie's Avatar
    Join Date
    Jan 2010
    South East Australia
    Replaced these before and in no amount of time they break up again. When they start to split i just cut them even all round and keep riding, doesn't seem to cause any noticable effect, Order from online and when you pull your pump check the clearance of the prop. We have a STX over here that has 400hours on it. Had props replaced though.

  6. #6

    Join Date
    Mar 2008
    Milwaukee, WI
    Well, First off Thanks for everyone's advice, I just wanted to give an update. I replaced the rubber seal, which was easy to do, and really didn't take all that much time either and still had the same problem after replacing it. So I brought it home, changed spark plugs and checked the air box/filter thinking maybe something got in there and nothing, but with the airbox out I did notice that there was a small hole in the exhaust coupler (Rubber coupler between the exhaust manifold and the first waterbox). It was about 1/4"-1/2" wide and about an inch long so I got a new one and replaced it, which was a pain in the ^$$ to do without pulling the exhaust manifold or exhaust pipe off. It was a very tight fit but I had just enough room to get the old coupler off and the new one on and that did the trick; I'm back to full speed and acceleration once again. So it must've over heated and caused it to burn that hole through and then the engine was sucking exhaust fumes in. I'm just glad it's all done now. Thanks again everyone!

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