Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

[Shane0524]

It does it at all speeds, a little less at idle, but some times it will do it and some tines it won't, it doesn't do it all the time, also when it does it I will put it in neutral and it stops but other times neutral doesn't stop it and I have to turn off the engine to make it stop. Please help me with any ideas also when it does the noise it still pumps water,so I don't think it is an impeller but it doesn't not sound like metal on metal.
could it be the flywheel it is the only thing i could think of that i have not checked is there bearings in the flywheel that could go bad

please view videos and let me what it sounds like

http://www.youtube.com/watch?v=6f6ed...1&feature=plcp

http://www.youtube.com/watch?v=W1reT...feature=relmfu

http://youtu.be/Lik66OmD_FI

 

[pvanv]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

It sounds like a harmonic vibration. Made stronger by the mounting method. I bet it doesn't do it in a test tank. There are no bearings related to the flywheel. Try the motor on a different boat. If no noise, get a different motor mount, or dampen the one you have.

 

[Shane0524]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

it is on an inflatable boat with inflatable floor is that possible on this kind of boat??

 

[pvanv]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

That motor is on a bracket on a sailboat. Not an inflatable.

 

[Shane0524]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

That motor is on a bracket on a sailboat. Not an inflatable.

Yes i understand that...the video with the sailboat was not my video it was a link to a video of an engine making the same exact noise....the other two links of of my boat and engine on my inflatable

 

[pvanv]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

The first 2 links don't load. Something about validation. Is your inflatable one with a metal-wrapped transom? The sail movie sure sounds like a mounting vibration.

 

[Shane0524]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

The first 2 links don't load. Something about validation. Is your inflatable one with a metal-wrapped transom? The sail movie sure sounds like a mounting vibration.

i think its a fiberglass covered wood transom with a metal plate. my sound is exactly like the sail vid

 

[pvanv]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

You may have a harmonic vibration. You could put a rubber pad on the transom (like a "blanket"), and then clamp the motor to that to see if the sound goes away.

 

[JOSEPHC]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

You may have a harmonic vibration. You could put a rubber pad on the transom (like a "blanket"), and then clamp the motor to that to see if the sound goes away.

try antivibration pads from Grainger...part # 4C973..about $11.00

 

[Shane0524]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

I have not had time to try that but I was running the engine out of the water in a bucket and it was in neutral and it made the noise. It was comming from the lower unit region but not in the gear area. More like where the impeller is, is there anyway it could get a vibration in the drive shaft or impeller or anything else down there. But it isn't comming from the upper engine itself it's down low.

 

[TOHATSU GURU]

Re: Tohatsu 4 hp making strange vibrating humming noise. Flywheel???

Harmonic vibration due to whatever. It could be anything from a bent driveshaft to an engine stand. Regardless, carpet or rubber over the transom ALWAYS solves the symptom.