Berkley jet
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Berkley jet

  1. #1
    Frank my lord Blown$um's Avatar
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    Default Berkley jet

    several questions? And heres my problems. I pulled jc pump out of my hawiian jet cause it started cavitating when i would try to launch boat hard, bad enough i half to back out of it to about half throttle then roll back into it. Its never done this before and kind of came about suddenly? One trip at lake boat was fine, month later took boat out and its been like this every since? There was one thing different tho, the gear oil was leaking past the seal pretty bad. That why i pull to inspect unit condition and measure all the wear? The wear ring to impeller is .030 total, the impeller really looked good no dings in the veins or rub marks any where. Is that wear exceptable? I do have another impeller like new, no measurable wear. But test fitting it and measuring its at .025 to the wear ring. So its tighter and was going to use it but noticed a problem, the hub on the impeller where it butts up against the flange on the shaft is .060 longer which is not allowing the impeller to fit completely through the wear ring like the original one did. And from inside the housing the original had about .020 from the impeller lip to the flanged edge inside the housing. With other impeller thats new/used has about .060 gap to the flanged edge. when looking at it, even tho its tighter than the original i think it wont seal correctly cause of gap and less wear ring contact area.
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    Last edited by Blown$um; 04-25-2015 at 06:24 PM.
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  3. #2
    Frank my lord Blown$um's Avatar
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    Oh yah, packing in great condition. Clean out hole o ring like new, but freind of mine told me that on his flat bottom if he needed a few hundred more rpm he would spray wd40 on his prop and it would slip, burn out a little longer than normal? I dont really know how true that is but if it was? Do you think that gear oil on my impeller could be making it cavitate.
    Last edited by Blown$um; 04-25-2015 at 06:22 PM.
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    Frank my lord Blown$um's Avatar
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    Really? Nobody knows anything about jets? No other opinions as to what could be happening?
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    Senior Member Mr. Denton's Avatar
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    The only jet I've ever owned was a PWC. But I had a similar sudden problem like you described here. It turned out I had lost the shaft seal. No water leaked in, but when the impeller was pulling hard, it would suck air from the engine compartment through the seal causing cavitation.
    In the defense of others and their slow response, Saturday nights are usually not spent starring at a computer waiting to solve someone's pump problems. Let the hangovers where off, I'm sure someone will be along shortly.


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    tintingsandiego krusn56's Avatar
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    Do you have a droop or preloader? Are you saying your wear ring clearance is .015/.030 a side or .030 total for both.
    Last edited by krusn56; 04-26-2015 at 08:20 AM.
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    Senior Member jetboatperformance's Avatar
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    "several questions? And heres my problems. I pulled jc pump out of my hawiian jet cause it started cavitating when i would try to launch boat hard, bad enough i half to back out of it to about half throttle then roll back into it. Its never done this before and kind of came about suddenly? One trip at lake boat was fine, month later took boat out and its been like this every since?" Often times a performance scenario like this occurs with the ingestion of a small rock or stick , rope etc , "junk" can then drop out when the boat is retrieved and put back on the trailer, or foreign material can also eventually pass thru driving in prior to inspection making diagnosis difficult

    There was one thing different tho, the gear oil was leaking past the seal pretty bad. This suggest a failed bowl seal in Berkeley, could simply be worn , combined wear of tail shaft, bowl bushings and and or bowl seal, fouled seal (fishing line, sandwich bag etc) worse case (but least likely) a bowl crack

    That why i pull to inspect unit condition and measure all the wear? The wear ring to impeller is .030 total, the impeller really looked good no dings in the veins or rub marks any where. Is that wear exceptable? .030 total clearance (wear ring ID to impeller skirt OD total is large by a bit according to what I read, but shouldn't present as serious cavitation like described

    I do have another impeller like new, no measurable wear. But test fitting it and measuring its at .025 to the wear ring. So its tighter and was going to use it but noticed a problem, the hub on the impeller where it butts up against the flange on the shaft is .060 longer which is not allowing the impeller to fit completely through the wear ring like the original one did. And from inside the housing the original had about .020 from the impeller lip to the flanged edge inside the housing. With other impeller thats new/used has about .060 gap to the flanged edge. when looking at it, even tho its tighter than the original i think it wont seal correctly cause of gap and less wear ring contact area. Again this forward skirt spacing or clearance is important even with what looks like a non-shouldered wear ring however assuming I'm reading your description and measurments right the amount you describe shouldn't cause the condition you indicated or cause issues going forward , to move that "newer" impeller forward you could machine a small amount off the nose of the center hub

    feel free to call if you need more help Tom

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