Wear on impeller shafts?

[bthessel]

So I pulled both impellers as I am planning on changing the bearings and resealing around the grates and pumps to hopefully stop some cavitation I am having. When I pulled them out I am seeing some shiny wear on the left shaft versus the right. Is this something I should be concerned about?

Left - Notice the 1 inch shiny band and and the larger bands at the top
https://photos.app.goo.gl/eerHkxYOwur1LLeC3



Right - Smaller bands of shiny area
https://photos.app.goo.gl/Q1cBnlxDAn7XjS8P2

 

[bronze_10]

The shinny ring at the end could be where it is rubbing where it goes into the splins... not sure about the middle

 

[bthessel]

The shinny ring at the end could be where it is rubbing where it goes into the splins... not sure about the middle

Ya, it's the one in the middle that seems weird. I didn't notice the difference till I got back home. The boat is 3 hours away now to look more at it where the shafts go in

 

[bronze_10]

Maybe there was trash on it at some point... not sure how much it would take to polish it to a shine like that.

 

[Scottintexas]

Did you ever suck up a rope?

What was your cavitation symptoms? just loss of speed, vibration, hole shot, noise??

 

[bronze_10]

I have been lucky... i have not done it yet but judging from some of the blpicturws i have seen it is likely to shut you engine down because one end is attached to the boat still. ... i have also seen pics where something wrapped around the shaft and they kept driving with it and it punched through the fiberglass...

If some trash made that mark on your boat then it wpuld prob be somwthing like fishing line or somethong that would not turn with the shaft to polish if like that. Is there a grove there? Can u hook your finger nail on it?

 

[bthessel]

The cavitation problems are actually the other one. Pretty sure its due to missing sealent around the grates and pumps, when I pulled that side there are a lot of gaps/ hard edges. On this one that is polished like that it is not work enough to stop my finger nail accross it so I wonder if it was just some like some fishing line that got in there and polished it smooth.

I had some water in the cones when I pulled them so figured I would change bearings and switch to oil bath while I wait for spring.

 

[Cobra Jet Steering LLC]

Top are from the seals at the intermediate coupler the other one was from something that was on your driveshaft it is right by your intake grate so a stick or something was there for a short time Honestly You need to inspect the grease in your pumps if it is good and no sign of water plus the bearings turn smooth I would not mess with them . Yamaha pumps last a long time, most cavitation is usually the impeller or the liner , I go 600+ hours on pumps with no issues with the pump bearings as for replacing the impellers if they are bad yes but it is a huge pain in the butt to get them off the drive shaft so if they don't need it don't mess with it. I know cavitation is a real pain in the butt however eliminate all the easier causes and look closely at the pump liner for dark spots where the impeller may be rubbing on it from corrosion under the liner. If it aint broke don't mess with it.