Started looking at my bearings and its not good

[Johnny16]

So with the weather getting a little warmer and life giving me a chance to breath, I decided today was the day to head out to the storage facility and pull the impeller shaft and duct housing off of the boat. It was really quick and easy and I was on my way home with shaft in hand for further inspection.

I took it to the bench and pulled the three screws out and pried the cone off with a screw driver. The cone came off pretty easy and I was greeted with some rusty water, a couple of loose ball bearings, and a mixture of black and red grease. I cleaned off the grease on the bearing and I could see the the bearing race was bent and popped out of the bearing. I was able to pull it out with my fingers. This was not what I wanted to see when I removed cone. This boat is new to me and I've only had a chance to get on the water once before the winter hit. The engine ran great but I was having cavitation issues and I'm assuming that this could be part of the reason.

 

[Johnny16]

Now I start looking at the back bearing and I notice that it's all ready loose on the shaft. I have play back there when I'm pretty sure I'm not supposed to have any and I can see where the bearing should be pressed onto the shaft. I thought I would quickly post my findings and see what you guys think. Now I'm headed back out to give it a little closer inspection.

 

[Bruce]

Looks like a rebuild is in order. Hopefully the shaft and housing are salvageable. I also believe that you have aftermarket impellers.

This post is from when I changed my bearings and will likely be helpful. https://jetboaters.net/threads/chan...-and-switching-to-oil-bath-lubrication.10155/

It is not a big or expensive job as long as the big parts are ok.

 

[swatski]

I also believe that you have aftermarket impellers.

Yep, I think @Bruce is right on. Solas Dynafly DF 14/20. If those are in good shape, people generally love those, it is considered an upgrade.
Looking at the pics of your bearings - those certainly need attention! - but I do not think that alone is the cause of your cavitation (impeller slippage) issues. More likely pump missing sealant (around the transom plate usually), or impeller dings - easy to check for it, or the OD diameter - if the gap between the impeller and wear ring is too large. Also check for bulges in the wear ring, especially if you are in salt. [EDIT: never mind - looks like you are in Alberta!] @Cobra Jet Steering LLC has posted here some great methods of dealing with that without buying expensive new parts.
That 14/20 pitch - if that's what you have - should be aggressive enough I would think, those impellers should not really cavitate much (unless they are bent out of specs of course). What are your max RPM? Your boat model is listed as "jetcraft" but I'm assuming it's a yammie. Are you close to 10,000 at WOT?

 

[Beachbummer]

I see that you dodged a bullet here. Finding this before further damage means you get to replace the bearings only. This is great news as far as I'm concerned. It was sick, but there will be no scar once you are done, and it is the cheapest possible repair.

Look on the bright side! Cheap, and you caught it in winter. May we all be this lucky.

Best of luck.

(To OP, Sorry you did not like my post. I still hope you have a quick return to full mechanical function)

 

[Johnny16]

Looks like a rebuild is in order. Hopefully the shaft and housing are salvageable. I also believe that you have aftermarket impellers.

This post is from when I changed my bearings and will likely be helpful. https://jetboaters.net/threads/chan...-and-switching-to-oil-bath-lubrication.10155/

It is not a big or expensive job as long as the big parts are ok.

I have read your post quite a few times and my plan is to use the island racing jet pump grease instead of the oil for now. As far as the big parts go I will be replacing the impeller housing as there a few scrapes in there. I think the impeller was rubbing. When I bought the boat the guy told me he had just put a new impeller in and it was a 14/20 solas

 

[Johnny16]

Yep, I think @Bruce is right on. Solas Dynafly DF 14/20. If those are in good shape, people generally love those, it is considered an upgrade.
Looking at the pics of your bearings - those certainly need attention! - but I do not think that alone is the cause of your cavitation (impeller slippage) issues. More likely pump missing sealant (around the transom plate usually), or impeller dings - easy to check for it, or the OD diameter - if the gap between the impeller and wear ring is too large. Also check for bulges in the wear ring, especially if you are in salt. [EDIT: never mind - looks like you are in Alberta!] @Cobra Jet Steering LLC has posted here some great methods of dealing with that without buying expensive new parts.
That 14/20 pitch - if that's what you have - should be aggressive enough I would think, those impellers should not really cavitate much (unless they are bent out of specs of course). What are your max RPM? Your boat model is listed as "jetcraft" but I'm assuming it's a yammie. Are you close to 10,000 at WOT?

I think your right swatski, I don't think it is the full reason for the cavitation but I think it's playing a part. If you look at the second picture in my original post, you can see that my spacer ring is jammed over top of the nut on the end of the shaft. I can't even get a wrench on the nut. I believe when the previous owner swapped out the impeller he forgot to put on the washer before he put on the nut. Because of this i think that the shaft had some play causing the impeller to slide back and forth in the housing. The motor sounds great and I have no issues hitting 10000 RPM at WOT. My problem is that I have to ease into the throttle or else I will cavitate. I also notice that when I hit 8500 it starts cavitate and I can't get any more out of the boat.

 

[Johnny16]

I see that you dodged a bullet here. Finding this before further damage means you get to replace the bearings only. This is great news as far as I'm concerned. It was sick, but there will be no scar once you are done, and it is the cheapest possible repair.

Look on the bright side! Cheap, and you caught it in winter. May we all be this lucky.

Best of luck.

(To OP, Sorry you did not like my post. I still hope you have a quick return to full mechanical function)

It defiantly could of been worse beach bummer and I consider myself lucky. I look at is a valuable learning lesson and good way to figure out how to fix and maintain my boat. Luckily it is winter and I have time on my side to get everything done.

 

[swatski]

Because of this i think that the shaft had some play causing the impeller to slide back and forth in the housing.

Those aftermarket impellers like Solas and Skat should sit pretty close to the vane segment when installed, moving smoothly but with not back and forth play:


If your impeller(s) could slide forward that might explain the cavitation/ventilation you describe - clearly way too much. The good news is, this should be pretty strait forward to fix and the results should be amazing.

--

 

[DCB-270]

I am having cavitation problems with my Sola's. Put the stock prop's on and much better. Now I can hear some noise when the motor is running. Might be time for me to tear it down and look at the bearings.
I guess I have a winter project.

 

[Speedling]

Those aftermarket impellers like Solas and Skat should sit pretty close to the vane segment when installed, moving smoothly but with not back and forth play:
View attachment 66013

If your impeller(s) could slide forward that might explain the cavitation/ventilation you describe - clearly way too much. The good news is, this should be pretty strait forward to fix and the results should be amazing.

--

I believe the Skats sit closer to the vein and it depends on what solas you get. I have to look up what I purchased cuz I don't remember, but I have a pretty good gap. (Solas Dynafly 14/20's - just looked it up.

 

[DCB-270]

I couldn't get my Solas 14 20 to hook up. Now I'm thinking t bearings had something to do with it.

 

[zelone]

For you guys with the older style 21' boats, there is a well known issue with missing silicone between the pump and the hull. I had a major cavitation issue on my 08 212, and removing and resealing the pumps fixed it. I noticed on one side, cant remember which, there was a larger gap at some spots in the tunnel, where the pump meets the hull. Clean it up real good, scrape all the old silicone off, acetone it, and reseal with a high quality silicone and you'll be good to go! I had a long thread about this on the old site. I'll see if I can find it.

 

[zelone]

Can skip to page 3 for specifics if its not already on page 3.
http://yamahajetboaters.com/forum/viewtopic.php?f=242&t=29435&start=30

Mods delete if not allowed.

 

[Scottintexas]

@zelone absolutely allowed,

I would ask since that's your post, could you copy and paste the info here on a new thread and we can add it to our FAQ/Tips. I couldn't open that link without signing in.

 

[zelone]

Hmm, I'm trying to figure out what the best way is. Theres alot of large pictures that I don't have saved anywhere else. I can screen shot it on my phone and post it that is ok?

 

[bthessel]

@Johnny16 did that fix your cavitation issues? I have almost the same issues on my boat, under load from a dead stop, like trying to get a wakeboard up, the starboard engine cavitates bad. I can also get it to do it when not pulling anyone by just pushing the throttle on that engine and not the other at the same time. If I push them both hard together when not towing it may cavitate for a second then it is fine.