Cavitation problem

[John Mcpartland]

Could this be the cause of my cavitation?
This was from cutting off my nylon rope that was sucked up and melted then instantly hardened into a nylon bushing around the shaft

 

[swatski]

View attachment 63974
Could this be the cause of my cavitation?
This was from cutting off my nylon rope that was sucked up and melted then instantly hardened into a nylon bushing around the shaft

No. (IMO)
That damage to the shaft (these scrap/cut marks) would have no bearing on cavitation. Some impellers have cones to smooth the transition between the shaft and the impeller neck - but then many racers actually leave those out. I once inadvertently left an impeller pulling tool on the shaft (that was a Skat impeller, but same difference), run the boat all day long - didn't notice a thing (until I started looking for the tool).

However, any loss of sealant in the intake tunnel or between the pump segments that causes the pump to suck air will cause cavitation. Also - loss of impeller OD specs - "loose" fit inside the wear ring will cause cavitation.

So - the rope might have damaged/ bent the impeller blades (messing up the OD, outside diameter) or removed some sealant from the intake tunnel or between transom plate/wear ring/stator (pump segments).
I would start there - pull the impeller shaft and inspect the impeller/wear ring clearance (gap) and possible gaps/loss of sealant that need to be resealed. 3M 5200 is your friend there.

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[John Mcpartland]

I just did the whole inside of the intake with 3m 4200, that is why the impeller was out. Good to know I don't have to buy a new impeller shaft

 

[swatski]

I just did the whole inside of the intake with 3m 4200, that is why the impeller was out. Good to know I don't have to buy a new impeller shaft

The shaft is fine I'm sure, and if you have it out - I'm sure it moves freely in the bearing inside the stator segment/cone, I really wouldn't worry about it.
The biggest danger with sucking a rope is - it can form a cocoon (spooling around the shaft) and literally destroy the (fiberglass) tunnel and the intermediate bearing int he transom - by expanding.
Obviously nothing to worry about in your case!

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