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Renegade jet
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472 Posts
Discussion Starter #1
I have a 21'6" renegade open bow(similar to an ultra). It is a big heavy family style boat. Even after having a fresh wear ring installed and the leading edge of the impeller detailed I am still experiencing a lot of cavitation. I have a legend pump with an A impeller and a place diverter. The pump is set back with the hand hole completely outside the boat. I have read that not having a ride plate on a setback pump may cause this. Any suggestions?
 

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Add an inducer it will load the pump harder and eliminate cavitation,my thoughts.
 

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Renegade jet
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472 Posts
Discussion Starter #3
I had thought about that also, but I feel like the pump is sucking air all the time. From idle through about 4000rpm it just never feels like it is fully hooked up.
 

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It shouldn't be pulling air thru the intake once you have some good forward momentum.

It could be pulling air thru the shaft packing.

Sent from my XT1096 using Tapatalk
 

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Renegade jet
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472 Posts
Discussion Starter #6
I will double check the packing before I take it out next time, but I just recently tightened it and it made no difference. The wear ring is brand new and the leading edge of the impeller was recently detailed.
 

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First, when did this problem appear? Were there any changes to the boat before vs after?

I couldn't figure out the pic you posted- But I am half blind.....Anyway, You definitely need a ride plate behind the pump....The pump can pull air in even after you're on plane. Also, you should check your packing, and also your clean-out hole cover seal- There should be an O-ring there.

I have a CVX-20 jet (2200 lbs) with 400 hp and a legend impeller in a Berk JE pump....I never have cavitation- except whenever I suck a chunk of driftwood into the pump and it wedges on one of the impeller blades.
 

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check for a gap at the seams where the intake and the suction connect fill with silicone check or fishing line also in the bowl vein could have debris in one of them (rock or piece of wood) ,,,all check out good install an Inducer problem solved . also bad wires or bad plugs could make you think you have a cavitation feel.
 

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Renegade jet
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472 Posts
Discussion Starter #12
This has been an issue since I bought the boat. I bought it over the winter so I only heard it run on the trailer. I haven't checked the handhole cover, but I will definitely do that. I think the bowl is clear since I had the pump gone through by a pro. Also the performance of the engine seems perfect it still tops out in the mid to upper 50's.
 

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Renegade jet
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472 Posts
Discussion Starter #13
Just checked and was hoping it was just a handhole O-ring, but it was there and in good shape seated properly.
 

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Renegade jet
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472 Posts
Discussion Starter #15
Just the stock rock grate. This has got me stumped. The boat seems to be completely stock the way it came from renegade. I can't imagine that if it performed this way they would have been able to sell any of them.
 

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Renegade jet
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472 Posts
Discussion Starter #16
I installed a rideplate since I have been wanting one anyway, but it didn't help the cavitation issue.
 

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I hate when problems don't go away......First, get a good look at the impeller blades and make sure you don't have any debris lodged on one of the vanes.....Then, check to see if your packing is leaking when sitting....If it leaks excessively, you may be pulling air thru the packing while running....Last, and I hate to bring this up; Take the bowl off and check it for debris....Stretching it, but we are running out of possibilities!

The only other thing, and a really bad one from the standpoint of having someone go thru the pump; Check to make sure that the guy who detailed the impeller and wear ring installed the KEY...the one that keeps the impeller from spinning on the shaft....Really remote, and I believe you said it hadn't changed from before to after the reworking......But it's a crazy possibility.....Those are the kind that get me every time!
 

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Renegade jet
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472 Posts
Discussion Starter #18
I'm beginning to think it might be the packing glad. It just seems like it is always sucking air.
 

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Renegade jet
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472 Posts
Discussion Starter #19 (Edited)
I checked the packing gland and it was leaking about a drip per second. I tightened it up and now drips about a drip/minute. The boat seems to be a little bit better, but still feels like it is sucking air till about 4000ish rpm.
 
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