4 hp Nissan strange noise.

[Mojo22]

Re: 4 hp Nissan strange noise.

Problem solved - again! The new prop did NOT fix my noise issue. Eventually the vibration/noise returned. So removed the lower unit and discovered that the drive shaft was coated with a lot of dry rubber. I can only guess that the drive shaft passes through some rubber bushings on its way to the head unit. Cleaned off all the traces of rubber and applied a bit of synthetic grease onto the shaft. (Also replaced the water pump impeller while accessible.) Put the whole assembly back together and have not heard the noise since, and this is after several hours of continuous useage. If you still hear your noise, Shane, I would suggest removing the lower unit (it's simple to do) and checking the drive shaft for signs of dry rubber. It's worth a shot.

 

[pvanv]

Re: 4 hp Nissan strange noise.

Long models have a stabilizing bushing the the exhaust housing to prevent the shaft from whipping. It's a bronze sleeve in a rubber mount, fitted into an aluminum casting that is retained by 2 screws that attach to the housing. Yours may have [partially] failed.

 

[Shane0524]

Re: 4 hp Nissan strange noise.

Problem solved - again! The new prop did NOT fix my noise issue. Eventually the vibration/noise returned. So removed the lower unit and discovered that the drive shaft was coated with a lot of dry rubber. I can only guess that the drive shaft passes through some rubber bushings on its way to the head unit. Cleaned off all the traces of rubber and applied a bit of synthetic grease onto the shaft. (Also replaced the water pump impeller while accessible.) Put the whole assembly back together and have not heard the noise since, and this is after several hours of continuous useage. If you still hear your noise, Shane, I would suggest removing the lower unit (it's simple to do) and checking the drive shaft for signs of dry rubber. It's worth a shot.

Thanks for the info. I did remove the lower unit to change the impeller about 6 mo ago. The drive shaft was coated with black carbon/ exhaust. I don't know if that's what you are talking about with the rubber because I never saw any. Where exactly was the rubber coating? After I reassembled my engine it did not make the noise for several days, maybe a week. I was so happy I thought I fixed it with the pump. I hope that doesn't happen to yours. Where did you put the lube? Thanks

 

[Mojo22]

Re: 4 hp Nissan strange noise.

I called it "rubber" but that's not really accurate. I agree that it was more of a black carbon material indicating burning - however the shaft was not worn at all and the material was easily removed with light sanding. There were at least two areas where the coating was clearly seen - wish I would have taken a photo - I'd say the top third of the shaft. I greased the entire shaft and slid it through the bushing then removed it, applied a bit more grease and assembled the unit.

Just wondering -- If the shaft were to bind up in the bronze sleeve (thanks Paul) then could the entire bushing have been spinning in the bushing housing? That could certainly explain the type of noise we heard.

 

[pvanv]

Re: 4 hp Nissan strange noise.

Yes, that could [maybe] happen. Normally, there is a lot of clearance between the ss shaft and the bronze sleeve, and it's bathed in water from the exhaust all the time... but... if you had a ton of carbon, I suppose that could close the gap, and make the bronze hang up on the shaft... making the rubber come loose from it's retainer. In that case, I would expect the "guts" of the bushing to have come down with the shaft when you pulled the LU. But... stranger things have happened.

 

[Shane0524]

Re: 4 hp Nissan strange noise.

Ok I have a short shaft so I don't think I have the stabilizing bushing. But maybe the carbon build up had something to do with it, but I should not have to scrub the shaft down every few days... So when you re-greased the shaft were you hopping that would keep the carbon from building up? I never re-greased the shaft and spline when I reassembled mine after the impeller change, which I know I should have done. So did you just rub grease all over the shaft? What kind of grease did you use? I'm thinking of taking it apart again And looking for obvious problems and greasing everything up really good.

 

[Shane0524]

Re: 4 hp Nissan strange noise.

Tohatsu/Nissan outboard noise problem - YouTube another video of the noise on my engine.... Also it has been making a little squeaking/screeching/rattle metal on metal noise ever so slightly. but only for a few seconds at a time wich can't be good. It's not low oil. And I believe only twice it made An extremely loud screeching metal noise and it stopped with lowing throttle. Something's up with it.

 

[pvanv]

Re: 4 hp Nissan strange noise.

Shane, Exhaust carbon on the drive shaft should not cause any sort of noise. Yes, the splines at the top of the shaft should be greased (you can use ordinary #2 lithium, just like for the zerk fittings, etc), but don't get grease on the very end of the shaft, or you may have a problem seating the shaft all the way. What is your serial?... you may still be in warranty, and a dealer may be able to help with that odd screech (or harmonic, or whatever it is). The metallic sound you mentioned might be something related to the recoil. If the recoil starter is not fully retracted, the lugs might come close enough to the flywheel cup to contact -- at least a little, causing that kind of sound.

 

[Shane0524]

Re: 4 hp Nissan strange noise.

I can't give you the serial because the engine is in a different state from me now, but I don't think there would be any warrenty because the engine is either and '06 or '07 model.

 

[pvanv]

Re: 4 hp Nissan strange noise.

Yep, too old for warranty service. Those motors had a 3-year warranty. Currently, they have a 5-year warranty. Either way, you are beyond the warranty period. The whine is probably just a harmonic, due to the installation/application. But if you get a metallic screech from near the top, that's likely related to the recoil starter.