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Discussion Starter #1
Hey Everyone,
I just bought a 77 Southwind with a 460 and berkley jet. The previous owner told me about a vibration that the boat has when its on the trailer. He said he tried to shim the "jet" and the vibration got better. I dont know too much about jet boats and was wondering if someone can steer me in the right direction. I just brought it out to my local lake and couldnt feel the vibration once it was in the water...


Thanks in advance,
Jon
 

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Angry American
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A vibration could be from a few places especially if it's on the trailer and no load on the pump. I'd be a whole lot more concerned if there was a vibration on the water.
The easy things to check are the motor mounts being loose, the drive line, debris in the pump and a loose alternator/belt. An out of balance flex plate/flywheel can cause a vibration along with a harmonic balancer that may have slipped or a loose balancer bolt.
From there it gets into the more difficult things such as engine balance, bent pump shaft, out of round impeller, and bad bearings in the pump. There's also at least a couple of other things that could cause it also.
 

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Discussion Starter #3
A vibration could be from a few places especially if it's on the trailer and no load on the pump. I'd be a whole lot more concerned if there was a vibration on the water.
The easy things to check are the motor mounts being loose, the drive line, debris in the pump and a loose alternator/belt. An out of balance flex plate/flywheel can cause a vibration along with a harmonic balancer that may have slipped or a loose balancer bolt.
From there it gets into the more difficult things such as engine balance, bent pump shaft, out of round impeller, and bad bearings in the pump. There's also at least a couple of other things that could cause it also.

Thanks for the info!! I'll double check those things you listed. I didnt notice a vibration while in the water
 

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U joints

U joints make alot of racket and vibrate. I wouldnt run the engine outside the water. JMO. After rebuilding my pump I found that the plastic that goes in between the impellar and the pump had melted away and the impellar had burn marks on the mating surface. But some do run them out of the water. I dont anymore. 700 bux to have it rebult last year.
 

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Hey Everyone,
I just bought a 77 Southwind with a 460 and berkley jet. The previous owner told me about a vibration that the boat has when its on the trailer. He said he tried to shim the "jet" and the vibration got better. I dont know too much about jet boats and was wondering if someone can steer me in the right direction. I just brought it out to my local lake and couldnt feel the vibration once it was in the water...


Thanks in advance,
Jon
The vibration could be completely normal due to the driveline possibly being too straight. If it's fine in the water I wouldn't worry about it.

Like Cas wrote you need to make sure all bolts are tight.
 

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A "staccato" kind of rythmic rattle and clunking that seems to transfer all the way thru the crankshaft is what we call "machine noise" very common when run on the trailer (no impeller load) more prevelant in solid mounts and aggravated by big cams , even worse with stainless and bronze impellers also made worse by any wear in the drive line spline vs pump shaft spline (wear) or anywhere else for that matter Tom
 
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