Prop swap and oops!

[WaterDR]

Welll, sometimes you live to learn.....right?

Anyway, I have a 115 Yamaha 4 stroke. It's a 2011. I hit a little sand this weekend and dinged-up the prop a little. It was really not bad. I would have left it alone, but had a spare of a different pitch, so thought it was a good excuse to swap. current prop is a 15p, the replacement is a 17p.

Anway, when swapping, I dropped a dam washer in the drink at the dock and could nto fish it out....lesson learned. Got new one.

Put on new prop, and rpms dropped by 1200! So, I got a new 15p instead and put it on and waiting for my original to be fixed....only $50 and will now have a good spare.

Anyway, right between 1200 to 1400 rpms, the motors sounds like it has developed some noise that I never had before. Hard to explain the noise, but sounds like a bearing type noise to me.

When I took off the original Yamaha prop, the nut could be turned by hand....it was kind of loose. When I replaced the prop, I got the nut on a lot tighter. Nothing crazy, just made sure it was snug. Did not use a tourque wrench, so I have no idea. But probably around 30 to 50 lbs by the calibrated arm.....hard to say.

Prop makes no noise when turned by hand and turns freely.

Could the nut be too snug? Or, could I have other issues?

Noise goes away completely at 2,000 rpms and seems to run fine.

 

[Texasmark]

Re: Prop swap and oops!

Prop nuts need to be tight to prevent damage due to shifting. My 90 hp owners manual says 55 ft-lbs. That's pretty snug. The noise you hear is probably prop looseness. You didn't do anything that drastic to tear anything up. Relax man.

Mark

 

[emoney]

Re: Prop swap and oops!

Sounds like a "paranoia noise", I'm practically an expert in this arena. Odds are you just didn't listen that closely before and now you are. I've made more imaginative problems over the years that they're pretty much inumerable (note my signature line). So, you're not alone.

 

[WaterDR]

Re: Prop swap and oops!

Thanks for the vote of confidence guys....I can be a nut job.

But, I don't think I am hearing things. Really sounds like a bearing to me. I wonder if it may be unrelated to the prop and could be the alternator. Sounds like a whine-type sound. I know sounds are impossible to diagnose on the internet. It is going in for some warranty work, so will have it looked into.

 

[Texasmark]

Re: Prop swap and oops!

You are hearing noises that you haven't heard before probably because you are operating the engine in a condition (load) that you never did before. Put your old prop back on when you get it back and then "worry" about funny noises.

Mark

 

[WaterDR]

Re: Prop swap and oops!

Boat is being operated the same way it always has. Had Yamaha mechanic involved and he thinks there is a shaft fitting not properly lubricated. Lower-end needs to be dropped under warranty. Told me I could run it like this if I want, it will just get louder and more annoying. Appears to be not related to the prop, just a coincidence. Course, won't know until it is apart. I will probably just wait until end of season.

 

[emoney]

Re: Prop swap and oops!

Sounds like a good plan (assuming the warranty isn't about to expire next week or something, lol). So how do you like that engine on a separate note? I'm just barely getting my toes wet, but I may be in the market next year for a new powerplant and that Yamaha is on the list. I know you've got a 'toon, but how well does it push your boat and is it quiet/fuel efficient? Thanks.

 

[82rude]

Re: Prop swap and oops!

somethings not right.if i read your post correctly you said rpm,s dropped by 1200!thats not possible with that small of a prop pitch change .not that it goes to the issue of your noise but maybe that 17p is has a spun hub.your prop isnt rubbing against the casing is it?some time differnt props need differnt spacers expecially between differnt brands .or ,you didnt do what i did once and completely forget the spacer(boner move on my part).

 

[WaterDR]

Re: Prop swap and oops!

somethings not right.if i read your post correctly you said rpm,s dropped by 1200!thats not possible with that small of a prop pitch change .not that it goes to the issue of your noise but maybe that 17p is has a spun hub.your prop isnt rubbing against the casing is it?some time differnt props need differnt spacers expecially between differnt brands .or ,you didnt do what i did once and completely forget the spacer(boner move on my part).

Nope, everything is mechanically sound and no parts missing. Both props are identical and brand new other than pitch. It's a pontoon, they don't plane, per se, so the rpm rules don't really apply in the same way. If I had a 16p prop, it would have likely gotten up into the power band better and had a much lower rpm loss. But, no one seems to make a 16p aluminum pitched prop.

 

[WaterDR]

Re: Prop swap and oops!

Sounds like a good plan (assuming the warranty isn't about to expire next week or something, lol). So how do you like that engine on a separate note? I'm just barely getting my toes wet, but I may be in the market next year for a new powerplant and that Yamaha is on the list. I know you've got a 'toon, but how well does it push your boat and is it quiet/fuel efficient? Thanks.

I reserached motors a lot before buying this one. The Yamaha is very quiet and they have a reputation of being bullet proof. I have a very unique seating layout, and my motor is not covered by a sun pad, so I wanted a quiet motor.

It seems fuel efficient enough.