I just got through building my waveblaster. It runs great but I have one issue. When the ski is idling in the water the pump rumbles. anything over an idle and it goes away. It doesn't do it when I run it out of the water. I had this ski completely apart and the midshaft and pump bearings turned smooth and quiet. I was wondering if this was normal or should I be concerned?
Pump rumble
- Thread starter fx1mark
- Start date
- Location
- Buffalo, NY
Good question.............I thought I heard a slight rumble noise in the back of my WB1 too, I also thought it might be my pump. Hopefully someone can chime in.
- Location
- Buffalo, NY
Mine only does it occasionally too, and only when idling and in the water, not out of the water. I have a Riva Red pipe.
- Location
- Buffalo, NY
I think I have this one solved. I thought my pump bearings felt fine on my 'Blaster too, and the pump was the only thing that I didn't rebuild when I went through the entire rest of the machine. Once I had my pump out, I noticed that the driveshaft was moving (just a little bit, maybe 1/8" or so) back and forth in the pump for some reason. I decided to tear the pump apart and put in all new bearings and seals. I just got done rebuilding my pump with new Koyo bearings (DO NOT use cheap Chinese bearings or ebay Chinese copies of actual Koyo or SKF bearings) and new OEM Yamaha seals. It seems like the driveshaft isn't moving in the pump now like it was before. I'm going to wager and say that this solved the problem, but I'll have to wait and see until I can get it in the water in about 3 more months. I also put in new Boyesen reeds, hooked up dual cooling, I got a Factory B Pipe with a Mod chamber to replace my Riva Red pipe, and a new Impros Hooker 9/15 prop instead of the 10/16 that I have on there now. I'm hoping that it ought to have a little more low end grunt now.
My problem turned out to be the exact same thing. the driveshaft could move forward and back slightly in the pump. I tried pressing the bearings back in but the shaft came loose the first time I rode it. When I took the pump apart the bearings could slide on the shaft even though they were tight. I rebuilt my pump also using koyo bearings. Yes it did the solve the problem and even though I changed out to a hooker 10/16 I do believe performance of the pump will be improved because the impeller will now be in the correct position up against the vanes. Sorry Jpswift1 I didn't post this when I discovered it because I assumed my issue was not the same as yours.
- Location
- Buffalo, NY
Thanks for sharing this information, Mark! I put mine all together and now the shaft has no back and forth play, but when I put the new front bearing on, it slid right onto the shaft without having to press it. I don't know if it's going to stay put in the correct positing or if I'm going to have to get a new driveshaft. Did your new front bearing slide right on, without having to be pressed on when you were rebuilding your pump?
Both my bearings pressed on tight. I think that you will still have an issue if they weren't tight. So one side pressed on tight and one did not? If so I would think you need a new driveshaft. One thought I had, which wouldn't be an ideal solution. It looked to me like the rear cap should sandwich the bearings in so that they couldn't move. But obviously there is a bit of a gap left. I thought about cutting the outside race of one of the old bearings down to try to fill that space. A kind of washer-spacer. Luckily for me it wasn't necessary to try.
- Location
- Buffalo, NY
Thanks for the heads up on this. Yes, my front bearing slid right on by hand and the rear bearing was the only one that pressed on somewhat tight. I think you're onto something with the idea for the spacer the two bearings. The Yamaha GP760 actually had a spacer that went between the bearings on the driveshaft and a nut threaded onto the end of the driveshaft along with a washer and it kept the bearings tight together. I'm thinking maybe I should get this spacer (part number 22 in the diagram from the link below) and then find a nut and washer that fits on the rear of the Waveblaster driveshaft. If that doesn't pan out, I may have to do a new driveshaft like you said.
www.partzilla.com
Yamaha Waverunner 1997 OEM Parts Diagram for Jet Unit 1 | Partzilla.com
Buy OEM Parts for Yamaha Waverunner 1997 Jet Unit 1 Diagram
www.partzilla.com
I am referring to here marked in red. The rear cone slides inside the rear of the pump. It should lock the bearings in place, but there must be a gap that would allow the bearings to move back towards the cone and allow room for the shaft to move forward and back. I was thinking I could measure that gap with something like clay (like checking a squish) and making a spacer to fill that space. The gap would be pretty small.
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- Location
- Buffalo, NY
That's a great idea! I the spacer (that you have drawn in red) would push against the inner and outer race of the bearings and when you tighten down the rear cone (which is held on with 3 bolts) it would hold the shaft and both bearings in place and they couldn't move at all. Thanks for sharing that diagram. I'm going to see if I can get a measurement on this and see if I can locate a spacer that would fit in there. I'm surprised Yamaha didn't do this from the factory to prevent these issues happening before could even arise.
The spacer should only touch the outer race as it is stationary, the inner race is moving. I was thinking about using the outside race of one of the old bearings. Cut a slit into it and it will slip right in. That way you can easily remove it for fitting. Then you would have to cut it down to the correct thickness. Use a cutoff wheel to cut it and then grind/sand it down to the final size.
The old races are also good for making a bearing driver tool. Here is one I made out of one of the old races.
The old races are also good for making a bearing driver tool. Here is one I made out of one of the old races.
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I should also mention that when I was putting my pump back together I used my micrometer to measure the distance from the outside rear race to the back edge of the pump and compared that to the lip of the rear cone and they were the same. Meaning there should not be a gap there. Clearly if that was the case the bearings should be captured and their should be no room for movement but on my first attempt to fix the problem I pressed the bearings in from the back and they did move forward the distance that the driveshaft was loose. Somehow it could be possible that the old bearings were slightly narrower than the new ones? I doubt it. You might want to go ahead and run your pump as it is and if you do still have a problem then either replace your driveshaft or try this shim idea.
- Location
- Buffalo, NY
I'm pretty sure the bearings that I replaced were the ones that were the Koyos that were in there originally when the 'Blaster was made back in 1993. I'm going to run it and see what happens. Thank you for replying and getting the micrometers on there to confirm this info. If I still get issues with the pump rumble, I'll get a driveshaft from a Yamaha couch ski and send it off to @Sasquachcrap and have him cut it down to the size for a 'Blaster. Stephen does great work and he's a great guy to deal with.
- Location
- North Carolina
Thanks for the tag. As for the spacer idea it should not be necessary. The bearings are likely failing. There is always continuous forward load on the front bearing when the pump is loaded. This is From the prop pressing the water back through the pump. The press fit of the rear bearing should hold it in place. If you suspect the sound is coming from the pump pull it and inspect it before you trash your prop and pump.
- Location
- North Carolina
Also pressing the two bearing together with a shim will create excessive side loading of the roller bearings and they weren’t designed for that. ( I would expect them to fail rather quickly).
Application you are describing would be like tapered roller bearing like found in a trailer axle.
Application you are describing would be like tapered roller bearing like found in a trailer axle.
- Location
- Buffalo, NY
Thanks for the info! This is exactly what I rebuilt my pump, I didn't want anything to get damaged and I didn't like that rumbling when I was idling out to our riding spots on the lake. I rebuilt my entire '93 "Blaster except for the pump, but now I just finished it up with brand new genuine Koyo bearings and OEM Yamaha seals and good synthetic marine grease. The shaft doesn't move in the pump at all and it spins nice and smooth.
Do you think that the driveshaft moving could have caused some issues with the pump not working as efficiently as it should have been? If the impeller (a Hooker 10/16 that I installed) was moving away from the stator veins in the pump just a little bit (due to the forward and back play I described), could I have been losing some power, especially on the bottom end?
- Location
- North Carolina
I would expect it wouldn’t be noticeable. But even idling it would have pressure forward on the shaft.
- Location
- Buffalo, NY
OK. I remember giving it a just a little bit of throttle and then letting off and idling down was when the rumble was most noticable. It sounded like something was vibrating loose in the back of my 'Blaster. If those bearings made it from 1993 until last Summer, I'd have to say I'm pretty impressed with their longevity and I don't think they owe me a thing. Hopefully the new Koyos that I installed in there when I just rebuilt it last that long.
The shim I was describing would not be pressed in and would only fill the gap that the bearings were moving in. When idling the pump would make a rumbling sound. upon inspection the shaft was able to move forward and back slightly inside the pump housing. I took the pump apart the bearings could slide on the shaft and allowed the shaft to move forward and back and would beat the bearings away from each other creating the gap that made room for the shaft to move. New bearings pressed on the shaft tight and the shaft no longer moves and the rumble is gone.