Waveblaster Cavitation/Pump Unhooking

[holjen77]

I built a 1995 WB1 backup ski over the winter. It has a 62T/61X with a riva red pipe. It run great, but when you spin it the pump unhooks and it cavitates. It also cavitates slightly out of the hole. I swapped in a backup pump with a different pump seal and it did the exact same thing. The midshaft looked almost new when i put it in, it was not showing any signs of seperating. I took the PTO cover off and it still looks good. Its done it since i put it in the water for the first time in the spring. I had a 1995 SD XP that did the exact same thing and it was the neoprene seal between the pump and shoe, but this one lloks good. Any ideas.

 

[jd0g]

Youve changed everthing ....
Sounds like yr sucking air, any water in the back. If the rubber tube between pump and mid shaft has a break it will suck air.

Other than that recheck you have a good seal between pump and shoe

 

[Nimmer705]

Have you installed a new pump shoe? Check to make sure the pump shoe isnt hanging below the bottom of hull. It needs to be smooth with hull.

 

[holjen77]

Replaced the midshaft and put black permatex on pump seal to get a leak free seal. Try it out over the weekend. Good call on drive shaft tube, I forgot about that.

 

[holjen77]

Still no luck. The drive shaft tube is good. It has the factory shoe and nothing is hanging below the ski. Really stumped on this, had cavitation problems on many skis and it was always a fairly easy and obvious fix. Any help or experience would be greatly appreciated. It seems when you lift the back of the ski up out of the water such as a spin or a sharp turn the problem gets magnified tremendously. I think i have swapped every part with my other blasters and getting no where.

 

[turboracer]

Did you check the shoe carefully for cracks? I had one with a barely visible crack do what you are describing to me. It was hard to see until I flipped the ski completely over and had very good lighting. The crack was caused by me using a screw that was slightly too long on the intake grate. Live and learn.

 

[holjen77]

I found this very small crack. Do you think its my problem? It does not go through shoe.

 

[turboracer]

Could be. Try to seal it up with some jb weld or silicone as a temp fix and see if the problem goes away.


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[Big Kahuna]

Sounds like your pump shoe may be leaking.

 

[jetx]

What impeller are you running? Have you checked your wear ring to impeller clearance, if it's too large of a gap it will cavitate

 

[holjen77]

I've tried known good pumps so I just ordered two new aluminum pump shoes. One for this ski and one for my daily driver as it broke Friday night while riding. I really hate changing these things. Last one took off a lot of gel coat with the green glue. Gonna try more heat this time.

 

[Vumad]

Just remember when replacing pump shoes they don't usually get bigger and fail. They usually warp slightly and cause a bubble the prop rubs on. It wears down the prop to the point that the diameter of the prop matches the bubble, not the shoe. You need to make sure the prop is in spec in your new liner. It could need repair.

 

[turboracer]

@Vumad
liner and shoe are two completely separate parts on a blaster.


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[Vumad]

I'm sorry. I spaced out there. I was thinking the liner the whole time even though I was saying the shoe.

Op said he changed pumps but could have used the same prop and had too much clearance.

 

[holjen77]

Pulled off the oem plastic shoe and found most of the green glue on the right side missing. I put a blowsion aluminum shoe and it run great. Thanks for all the replies.