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Thread: Hamilton jet slipping and no acceleration

  1. #1
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    Talking Hamilton jet slipping and no acceleration

    Hi, I have a 84 valco 21 ft with a ford 302 and a 750 series 2 stage hamilton jet. I'm getting slippage that feels like a car clutch slipping and has no acceleration.


    Supposed to have a cruse rpms around 3000-3200rpms but will do around 8 mph at those r's and will maybe do 30 mph around 4000-4200 rpm. It feels like hitting the gas in a car with it in park like it's not under any load. I have never been in any other jet boat and bought this as it is a year ago so I have no real comperison as far as speed and acceleration. Checked staters/ impellers and everything looks good, no gap, nicks or wear in the impellers of the stators, no blockages.


    Does 30 mph sound right? I seen a forum where a guy had a berkley and air was leaking into it, could this be my problem? I appreciate any info, I'll say thanks ahead of time

  2. #2

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    There's definitely something wrong. How much gap is there between the impeller and wear ring? If there's more then .010 I'd have them rebuilt.

  3. #3
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    No gap at all, impellers looked like they were reworked before I got it. Think I'm going to take it apart again and check it out.

  4. #4
    Member Jimw's Avatar
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    30mph is not bad but something is wrong. Berkley and Hami two different animals. 3000 3200 rpm you should be close to or on step with and empty boat. Check and see if the reverse bucket is out of the way of the nossle. Seen it happen once on a 773....
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  5. #5
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    Did you inspect the intake grate for debris?

  6. #6
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    There is a wear ring for the hamilton jets. If there is any groove at all behind the impeller, then there could be cavitation. If you run your fingernail over it and you feel a little ridge, then there is a problem and no matter how true your impellers are, you will have cavitation. It is really hard to visually inspect unless you have done it before. There are a host of things that will cause the wear ring to wear out, the easiest is just time on the jet in silty water. If you are not familiar with the hamilton, pull the wear rings and impellers and take them to a either Mel (halibutgrove) at AK Frontier Fabrication in Wasilla or Mike at Professional Marine in Anchorage.

  7. #7
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    Mike at professional marine just takes the impellers to AK Frontier Fabrication in Wasilla FYI

  8. #8
    Member akshootnscoot's Avatar
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    How's your transmission fluid? Could be the tranny slipping?

  9. #9

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    This is direct drive there is no transmission .

  10. #10

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    You gotta take it apart it could be anything , could be a rock between your blades could be a broken blade could be grass caught between impeller and liner . Give us some background do you pump lots of gravel? Did this start suddenly or over time

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