1996 Speedster Cavitation issue??

[speedsternoob89]

Took my boat out today. Was really stretching her legs and got her up to 45mph. This was after cruising around at about 30 for close to an hour. After turning around I accelerated out of the turn and started throttling up. Started to pick up speed and then the starboard motor revved very high and I could tell the thrust did not match the Rev. So I slowed to about 10mph and tried each motor. Both motors are now doing and I think the port maybe showing signs due to the increase in load while trying to accelerate. I crawled under the rear of the boat to investigate the intakes and there's no debris. However the plastic sheath around the port driveshaft is all but gone with only a small bit of it around the shaft next to the impeller. Please help.

 

[treimche]

From what I have read on here, those white plastic driveshaft protectors should just be removed.

 

[JeremyD615]

You need to put the shifter in Forward and look into the nozzles with a flashlight. You may find debris stuck in the pump, or you may find that the wear rings have come apart. There should be 1mm or less clearance between the impeller and the rings. If there’s more than that, or you have chunks missing, you’ve found your problem.

 

[speedsternoob89]

I checked both jets, no debris whatsoever other than the broken plastic driveshaft cover on the port driveshaft. It looks like there is a bit of gap around the impellers but it doesn't seem major, I ordered new wear rings and neoprene seal anyway. The impellers are stainless and the the veins are copper which are nice surprises. I'm going to check the carbon rings when I do the wear rings.

 

[speedsternoob89]

Top picture is starboard impeller. Bottom two are port.

 

[jts32]

I'd sharpen up the leading edges of the impellers also. Especially the port side, it looks pretty dinged up

 

[treimche]

I'd sharpen up the leading edges of the impellers also. Especially the port side, it looks pretty dinged up

Will little dings on the impeller edges cause cavitation? Mine have some but not as bad as speedsternoob89.

 

[jts32]

Yes it can. I think more so on the boats than the skis because of the extra weight you're trying to push.

 

[JeremyD615]

You definitely need new wear rings, but the driveshaft protectors are causing the bulk of your problem. It’s obstructing flow to that starboard impeller, and you’re not going to be going anywhere until that’s removed. It looks like the protector has part of it missing on the port side as well. I’d guess that you may have had a piece of it lodged in that pump as well, but it may have fallen out either putting the boat on the trailer or during the ride home. When you pull the pumps to swap the wear rings, just yank those plastic collars out as well so you don’t have problems in the future, and you should be good to go! You might take a file to smooth out the leading edges on the props, but they really don’t look bad at all to me.

 

[speedsternoob89]

Cool, thanks for the info! Got wear rings and neoprene seals ordered!

 

[speedsternoob89]

Do you guys recommend using loctite on the impeller threads and venturi bolts?

 

[treimche]

On seadoosource.com they used to have a note saying to use anti seize on the impeller threads so you can remove them in the future.