Time for a new prop ?

[Marvin willis]

The past couple times I've been out the port side has been cavitating if I start out fast and whining like bad ground through your speakers. And when I rinse the motor I use to hear some prop noise. Now none at all. This is all I could find when I took it apart. Opinions?

 

[Scottintexas]

mine look much worse but don't really give me any problems, cavitation is like a "magic bullet" it's hard to say unless it's really causing you issues,

I would also tell you to look at the sealant in the tunnel to make sure none is missing or loose, pull on it gently to see if it's still attached firmly, I had some that was there but the pressure would pull it away causing cavitation,

If you haven't already It would be a good time to check your impeller bearings and maybe even replace them at 12 years,

 

[Marvin willis]

New bearings and jet pump with plastic liner. Liners has very little scratches. When I spin the impeller in it the gaps vary

 

[Marvin willis]

I didn't think the prop looked bad either but i don't understand when I had a little clanging of impeller noise to none at all. I thought something happened to the liner but it looked fine

 

[swatski]

New bearings and jet pump with plastic liner. Liners has very little scratches. When I spin the impeller in it the gaps vary

If the gaps are within specs I wouldn’t worry, maybe just gently file those leading edge barbs but that damage does not seem too bad to me.

Is the pitch consistent between blades? You can measure it on a flat surface like a granite countertop with a ruler, no need for a pitch measuring tool.

If the gap between the blades and wear ring is too large - that can massively reduce efficiency, top speed and may cause cavitation.

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[Marvin willis]

What are the specs for the gap?

 

[swatski]

What are the specs for the gap?

Not sure this is model specific, but the gap is .35mm - .45mm

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[Marvin willis]

What would cause the high pitch whining

 

[Marvin willis]

It's up against the wall on one side and .50 on the other. Here are more pics

 

[Cobra Jet Steering LLC]

Well I was told by someone who does this all the time " MOBIL MECHANIC" not to use the plastic liners in the jet boats because they cavitate .
I use them in my skies with no problems but this member who I have a lot of respect for when it comes to the mechanical aspects of the Yamaha jet boats gave me his honest advice and he explained that he has had many issues with those liners. So I am passing that along

 

[Marvin willis]

I'll switch the jet pumps and see if the cavitation switches sides

 

[Gym]

I'll switch the jet pumps and see if the cavitation switches sides

Don't switch the impellers as they are side specific. Whereas you are touching the liner on one side and have .05 clearance on the other, along with the whine you reported, I'm thinking bearings.

I agree with Jeff, go back to OEM liners. My origionals lasted 10 years. I just replaced them last year and expect another 8 to 10 years from them.

 

[swatski]

I have had plastic liners in a 190 and liked them very much, actually. Not the red ones, mine were black and (presumably) made of delrin plastic. Those were very hard to get inside the wear ring, but doable - just needed some time in a freezer.
They were a very tight fit with new impellers, but that was great. Also much quieter, which in my 190 was a big plus - that thing was stupid loud.

The only disadvantage I noticed was they get damaged easily, even small gravel would mess them up. At $20 a piece - not bad though, other than some work.

Just my 0.02.

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[Cobra Jet Steering LLC]

Try removing the liner from the pump that is giving you issues and reverse it so the scars are on the opposite edge away from the impeller, I believe you can reverse those and use them twice. if it fixes the issue for a while it will let you know that was the problem.

 

[Cobra Jet Steering LLC]

thread on pump issues https://jetboaters.net/threads/horrendous-grinding-noise.13656/#post-237299

 

[swatski]

Try removing the liner from the pump that is giving you issues and reverse it so the scars are on the opposite edge away from the impeller, I believe you can reverse those and use them twice. if it fixes the issue for a while it will let you know that was the problem.

I would say: if one can remove the liner without actually cutting it out (or chiseling it out) - that is not a good liner! - and probably should not even be there in the first place as it may spin (as @Tom V pointed out in the other thread).
@Cobra Jet Steering LLC Thanks for the link, BTW! Good read.

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[Cobra Jet Steering LLC]

yes but most of these can be pressed in and out also on some older skies there were set screws to secure the liners from spinning so drilling and tapping a few spots in the housing would probably solve that problem however like I said I use a bit of 3m super duty weather stripping glue to secure the liner, but if his liners are loose then this is probably the issue and some quick dry 5200 would probably hold it long enough to test it out

 

[Beachbummer]

How does the sealant look? With the picture it appears there is a big gap between the sealant and the black pieces, but it may be a shadow.

 

[Marvin willis]

Are you talking about above? Yes it looks like a gap like the Sealant has worn away.

 

[Beachbummer]

Right. Those gaps need to be filled in and air tight. for the pieces that are never to come apart, 3m 5200 sealant will fix it for you. I just recently saw a thread on this same problem. That does not look like the original sealant either, have you re-sealed that before (or maybe prior owner if not you?)