Extreme cavitation

[cookerq62]

Ok so I switched from a limited chamber to a blaster mod. While my ski was down I pulled the pump to check the impeller (13/16 cut back skat swirl) for wear and swap back to the stock pump cone. Iget it back together and get the ski in the water and it rides fine. Then the pump starts breaking loose when I hammer it at low speeds. Eventualy I got nothin, It doesn't even hook up enough for me to stand on it yet its pounding off the rev limiter. I pulled the pump put it back to gether and it ran fine. I hit a wake and land then I got nothin. This goes on 2-3 times before I give up. So I pull the pump and check over every thing and find there is a pin missing at the front of the pump so I replaced it and I still got nothin. The ski will only go 3 mph tops. I am at a total loss trying to figure this thing out its almost like it has no reduction nozzle at all. Every thing is sealed, the pump shoe has 5200 all around it and the pump packing is still good. What is the tolerence for clearence between the impeller and wear ring? Any other input would help.

 

[cdubb]

I dont think thats cavitation,sounds like something stripped. Drive shaft,coupler,??

 

[cookerq62]

The coupler is fine and so is the drive shaft. I can't get the prop off without tools and it is on there solid.

 

[chrisdoc0608]

the wear ring clearance spec limit is .025''... but if it were the wear ring you would still go above 3mph after a few seconds it would just be slow to hook up

 

[chrisdoc0608]

is your pump seal on the right way? i accidentially put mine on backwards and had the same issues

also if you go out there when it is dark and put a light in the intake grate, you can get a good idea if there is an area not sealed up

 

[WaveDemon]

I was thinking pump seal too.

 

[cookerq62]

I have the square side on the pump and the other site with the flaps on the shoe and it is def sealing all the way around. Its so major and It is driving me nuts that I haven't figured it out yet.

 

[waterfreak]

put your pump on and inspect the pump seal . it should seal firmly againts the ride shoe.

 

[waterfreak]

alright, I know what it is!! check your intermediate housing!!. I have found that when the rubber break loose from the housing, it will cavitate like a bitch. It drove me nuts once on a waveblaster I was working on after replace almost everything in the pump

I'll bet $20 on this!! who's in?

 

[keefer]

If it is not the pump seal I have seen a boat act like this when the midshaft splines were stripped. The driveshaft looked ok but the boat would barely go. This was caused by improper engine alignment that put the shafts in a bind thus stripping them out.

 

[keefer]

alright, I know what it is!! check your intermediate housing!!. I have found that when the rubber break loose from the housing, it will cavitate like a bitch. It drove me nuts once on a waveblaster I was working on after replace almost everything in the pump

I'll bet $20 on this!! who's in?

Forget my last post. I did not even think of that. That would definitely cause his exact symptoms. I'll bet your right..

 

[chrisdoc0608]

what rubber are you guys talking abt in the housing? just courious

 

[dual_carbed_650]

i told him to check his intermediate as well, i was there on the shore today while he was testing it, if u need help working on it, or a place to do it at, we'll have some room in my garage this week. Or if u just want another set of hands to help ya let me know man.

 

[waterfreak]

what rubber are you guys talking abt in the housing? just courious

the intermediate housing is the bearing carrier that your small shaft and coupler go into and bolts on your firewall. If the seal is broken (like the rubber around the aluminium) it will suck air from the engine compartment and cavitate like a mofo.

I also take paypal !!
:Banane37: lol

 

[chrisdoc0608]

gotcha. thanks for the clarification

 

[RideItLikeYouStoleIt]

Mine did the same thing and was caused by a pump seal. I think the intermediate housing could do the same thing but havent had it happen to me. I also found out that if its your pump seal it will eventually catch up alil when water gets forced at speed and stop cavitating so bad. I dont know if an intermediate housing seal would act the same way.

 

[cookerq62]

it does take on water like a mf'r too prob more then just just coming from the scupper. I'll have to pull the motor and check it out. The midshaft is in need of a rebuild so it won't be a total waste of time.

 

[cookerq62]

I filled the hull with water and the bearing leaks so bad where it comes through the hull it can just about keep up with a garden hose. Thanx steve.