Could this be the source of my cavitation?

[bigtexan99]

On the last outings I started getting severe cavitation and had to feather the throttle up and down to get the boat on plane.

Took a look at the driveshaft today and noticed that the small boot on the engine side (with the zerk fitting where you pump in grease) is missing the stainless steel clamp. Found the clamp in pieces down under the engine.

Would the loss of that clamp cause enough free play in the driveshaft to be the source of my cavitation? I hope so as that will be an easy fix.

 

[manolocross]

Yes it can be but we need more info... What ski year and engine. A pic of the area would help a lot.


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[68ragtop]

On the last outings I started getting severe cavitation and had to feather the throttle up and down to get the boat on plane.

Took a look at the driveshaft today and noticed that the small boot on the engine side (with the zerk fitting where you pump in grease) is missing the stainless steel clamp. Found the clamp in pieces down under the engine.

Would the loss of that clamp cause enough free play in the driveshaft to be the source of my cavitation? I hope so as that will be an easy fix.

In reality, that rubber boot is there to keep grease in & water out. It really should effect cavitation at all. Prop and/or wear ring damage would be #1 Carbon ring probably #2, but less likely.

I had a GSX that had moderate cavitation. Pulled it apart & found nothing worn, or damaged. Replaced the wear ring because I had it apart anyway & I felt like I just threw away $60 at the time. But, it turned out to be the problem. It had just a little too much clearance even though it was still within spec. I also had an XP that I was running a skat trak swirl impeller. When I install a new wear ring on that ski, the impeller fit so tight it cut the ring to fit & plastic shavings came spiting out when I started it up. So it had zero clearance. That thing hooked up like craaazy.

 

[Strizzo]

In reality, that rubber boot is there to keep grease in & water out. It really should effect cavitation at all. Prop and/or wear ring damage would be #1 Carbon ring probably #2, but less likely.

I had a GSX that had moderate cavitation. Pulled it apart & found nothing worn, or damaged. Replaced the wear ring because I had it apart anyway & I felt like I just threw away $60 at the time. But, it turned out to be the problem. It had just a little too much clearance even though it was still within spec. I also had an XP that I was running a skat trak swirl impeller. When I install a new wear ring on that ski, the impeller fit so tight it cut the ring to fit & plastic shavings came spiting out when I started it up. So it had zero clearance. That thing hooked up like craaazy.

also the grease and pressure in the boot keeps rearward pressure on the driveshaft, so if the boot loses a clamp, it might not have enough pressure against the carbon seal.

 

[68ragtop]

also the grease and pressure in the boot keeps rearward pressure on the driveshaft, so if the boot loses a clamp, it might not have enough pressure against the carbon seal.

I know when you first pump them with grease, the shaft moves out a little because the grease as no were to go at first, but it seeps through the splines & the pressure is lost pretty quickly. I wonder if maybe he lost the rubber bumper on the end of the shaft? that's a possibility if seal is not tight. Is it leaking water into the hull? Any pictures?

 

[- BiRkS_]

I had a problem with my 98 XP. Had a new wear ring, new neoprene seal, thru hull seal fine. It would heavily cavitate while trying to get on plane then would "hook" and go like crazy until slowing back down. Turns out the silicone holding the ride plate was missing in some places and allowing air to get in around the pump. Some little silicone work and that machine is FAST! pulling 7200-7400 rpm. Speedo doesn't work, have to order up a sensor.

From what your first post stated. It sounds like the PTO boot band clamp gave out. You can buy a replacement, or on personal skis i've used a thomas and bits tie wrap. They are very strong and if you leave a tail, you can always re-tighten it.

 

[bigtexan99]

Thanks...its a 2001 Sportster LE. I accidentally posted in the wrong forum.

It sounds like the missing clamp could be the problem. Going to replace it tonight and try and water test tomorrow.

Pulled the pump off last night and impeller and wear ring look fine.

If it still cavitates I'll check back in and update.

 

[Coastiejoe]

I moved the post to the boat section with a 30-day redirect so you can find it easily..