1996 Seadoo Challenger Cavitation

[Dagray1971]

I recently bought a 1996 Challenger. Put the boat in water and was having intermittent cavitation problems. High RPM and only running 10 mph. I could manipulate the throttle and ended up getting it to take off. Tiring of the issue I took to Marina and they replaced the wear ring and impeller. Took the boat home and no better. Marina is stumped and so am I. Any ideas or help would be greatly appreciated.

 

[Isaac-1]

I am new to these boats too, but it sounds like you are getting a air leak going into the impeller pump, most likely causes are when they installed the pumps they did not use silicone sealant or a neoprene sealing ring, alternatively air may be leaking past the carbon ring on the drive shaft. Either one requires pulling the pump back off and reinstalling it the right way, possibly replacing the carbon ring in the process.

 

[Waterluvr]

There are two usual suspects on your boat to look for the issue now that you can rule out wear ring/impeller clearances.

1. The face of the pump needs to compress tightly against the neoprene seal on the pump support ride plate or it will draw air. If the neoprene seal isn't sealing it you may need to use some black RTV on it as well.

I always use a new seal and small bead of RTV in combination so it seals properly yet isn't a nightmare to pull apart.

2. The shaft seal in the engine bay, you may have a worn bellows not tensioning the carbon seal and stainless carrier ring sufficiently any more causing air to be drawn from the hull and into the pump.

 

[Dr Honda]

Isaac hit the nail on the head.

The only way to cavitation that bad, is to suck air. (I'd say the marina owes you $$ for a bad diagnosis) SO... with out even thinking about it... your carbon seals need replaced. Along with the boot, and possible the stainless ring if it's warn.

 

[Dagray1971]

Thanks for the info. I ordered a new complete carbon ring seal kit and hope that solves my problem. I'll update once I get it installed.

 

[Dagray1971]

Installed new carbon ring, bellows, o-rings along with the new impellar, wear ring and nose cone. Used all OEM parts, no aftermarket. Seems like cavitation isn't the problem now. The shaft seal leak is gone with new parts installed. Our boat in after all these repairs (done by the marina) and I racked out at about 4200 RPM and 20 mph. Have no power. Any other suggestions would be greatly appreciated. I've had the boat a couple months now and have yet to take it out on a successful outing. Thanks.

 

[ialonso]

Can you provide more details ? How does it "top out"? What if anything have you done to your fuel system? Have you recently checked engine compression? Can you see your reverse gate fully opening?

More details may help someone realize what's going on.