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Problem 2007 Yamaha Jet boat

Juan Negron

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Bruce the Impeller looks good I think the splines on the drive shaft are bad!
 

Juan Negron

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Bruce the impeller housing which I replaced thinking it was bad with a stainless steel unit, do I need a wear ring on this? I have the shaft and mid shaft out everything is tight I'm really confuse about this whole system!
 

Bruce

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Bruce the impeller housing which I replaced thinking it was bad with a stainless steel unit, do I need a wear ring on this? I have the shaft and mid shaft out everything is tight I'm really confuse about this whole system!
The factory impeller housing is made of aluminum with a stainless wear ring built into it. Some aftermarket housings use plastic wear rings.

If the gap between the impeller and the housing is not correct it will cause cavitation which will be noisy and reduce thrust significantly. Anything caught in the tunnel, on the impeller or shaft will do the same. Some have had cavitation issues that were caused by the silicone around the pump peeling off.
 

Juan Negron

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Another question Bruce when I install everything back together should some type of silicone be applied in between each housing?
 

Bruce

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tdonoughue

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So I have a question: How do you know that the engine is going but that the impeller is not moving? Did you run it on the hose and look?
 

Big Shasta

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If you have ever had a manual car with a bad clutch (rpms go up but speed doesn't) that's what cavitation feels like. It could be as simple as missing silicone around your driveline allowing air to get in.
 

tdonoughue

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@Big Shasta , you are right. But in those cases, the impeller is moving, just not being effective (due to cavitation). I was re-reading the OP and he said that the impeller was not moving. So I am trying to figure out if it just FEELS like that (in which case it could be cavitation) or if it is actually not moving (in which case it could be bad clutch, something jammed in the impeller or, least likely I think, the impeller splines).
 
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