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  1. #1
    BigT's Avatar
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    97 GSX Cavitation?

    Hey guys, new SBT rebuilt engine, starting third tank of gas, ran fine last week, got in the water today, had a hard time getting up on plane., rpms pegging 7000. Once up though, ran good, so stopped tried again. took forever to get out of the water, but once again once I was up, seemed fine. took it back in, set a minute tried again same thing. Impellor looks good, wear ring is good. checked to make sure didnt suck anything up the intake. Im lost here. Grabbed the shaft, didnt feel any play in it, same with impellor, seems tight. any ideas? thanks..... BigT


  2. #2
    Moderator RX951's Avatar
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    Welcome to the Forum !

    Are you sure the wear ring is good ? You may want to check the clearance between the impeller and liner. If there are many hours on that liner, its possible that the wear ring clearance is too big.

    Also, Does it have the old skool carbon shaft seal or the updated double lip bearing style ?

  3. #3
    BigT's Avatar
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    Im sure the wear ring is good. This thing ran great one week ago. Nothing done to it cept add some gas, and unplug the fuel baffle.
    Ive owned this since it was new. its sat for 7 yrs, thats why I went ahead and replaced the engine, has 90 hrs on it. Also it probably has the old carbon seal. It did have some water in the hull, however it was pretty choppy out last week when I took it out, so not sure if I have a bad boot seal or not?

  4. #4
    BigT's Avatar
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    Let me ask this, the mechanic who put the engine in for me, not sure if he aligned the pump with the engine . If this could have caused this, how long would it take? I mean I've probably ran this close to 4 hours before today. Does that mean anything or not? LOL I know the SBT installation procedure doesnt call for re- aligning, if it did, I missed it

  5. #5
    Moderator RX951's Avatar
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    Did you check the leading and trailing edge of the impeller?

    This seems to be pump related if it is cavitating.
    Wear ring
    Impeller
    Seal
    Impeller damage
    Clearance issues

    Have you pulled the pump or just do a visual from the intake and nozzle ?

    If the motor was not aligned properly, the carbon seal will not mate properly and air can leak while the motor is running and vice versa, water will leak in while it sits.

    Any slight leak of air thru that carbon seal will cavitate the pump area quickly as the suction of the pump will draw air into it.

    Anytime the motor is removed, the engine must be properly aligned.
    Last edited by RX951; 11-18-2006 at 08:46 PM.

  6. #6
    BigT's Avatar
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    Hey RX, just did the visual . where do you think I should start first? I'll get a feeler gauge in the a.m., and check the clearance, what SHOULNDT it be? Everything Ive read so far, indicates the carbon ring. How hard is that to get to and replace....BigT

  7. #7
    Moderator RX951's Avatar
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    Looking at manual, the specs call for the clearance to be

    Impeller/wear ring
    clearance
    New 0.0 - 0.4 mm (.000 - .016 in)
    Wear limit 1.0 mm (.040 in)

    It will begin to show signs of cavitation around .025-.030.

    If you have 90 hours on it, your RPM's are ramping up quickly and it takes a long time to accelerate, I would suspect that liner, especially if it the original one.

    I would check this first.
    also, inspect that impeller thoroughly for any cavitation burns, nicks, chips, dents.

    The liner may look good visually, but if there is a cavitation burn on it, it will cavitate badly.

    These liners are made to "wear". they are also very easy to replace and inexpensive.

    Last edited by RX951; 11-18-2006 at 09:08 PM.

  8. #8
    BigT's Avatar
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    Ok, I'll check first thing in the morning. This is gonna tick me off if the wear ring is bad. I specifically asked the mechanic to check it and replace it if it was worn. He told me it was good, lol he had it for two weeks, plenty of time to do it then, but nooooo prolly to busy workin on four wheelers lol. He's a good guy though, rebuilt the carbs,( they were bad after all this time) pulled the motor, put in the new one, changed the pump oil etc, one sponson, hell I dont remember everything, but with new battery etc.....was under 400 bucks.
    What I dont understand, is why it ran so good last week. Everyone always asks me why I have 3 skis, always say, Cause when one breaks down, Im not sittin still waiting for it to get fixed.........BigT

  9. #9
    Moderator RX951's Avatar
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    Well, I will say this, if the motor was not properly aligned, due to the floating driveshaft design that the older Sea-Doo's have, any misalignment will cause an accelerated wear on the wear ring.
    Coupled with a new motor with new power, if the motor is out of alignment by 1mm, it can cause the wear ring to wear by that much if not more. And 1mm ain't much, but remember 1mm is the "wear limit" on the wear ring to impeller clearance.

    * Also see how much water you are taking in thru that carbon seal as it sits in the water.

    * Did he pull the pump to change the pump oil?
    the pump oil can be done while on the ski. Just remove the cone.

    Anytime the pump is pulled the neoprene seal should be changed if it is compressed too bad or has many hours on it.
    A bad Neoprene seal can cause cavitation in the pump area. the neoprene seal seals the pump to the pump shoe/hull area.
    This neoprene seal compresses as the pump is bolted in to keep a tight seal.

    * Did he loctite and torque the motor mount bolts ?

    * Also, pull up on your motor and check to see if all your motor mounts are holding. Those older motor mounts are known to separate from the metal backing. I've seen a bad motor mount wipe out driveshaft splines.
    Last edited by RX951; 11-18-2006 at 10:12 PM.

  10. #10
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    I'll check on that neoprene seal on Tuesday, when he is open again. I see what your saying about the misalignment, makes sense when you put it that way, on that subject, I'll know something tomrrow first thing.
    Correct me if I'm wrong , but the carbon ring shouldn't allow any water in? If it is, that need replaced also? THANKs...........BigT

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