humming sound from the shaft when motoring

[411 owners]

I recently posted about groaning from the shaft when sailing and at times motoring. I got a mechanic to grease the seal and had to take the boat to a yard as I broke off the fitting aft of the seal that inputs water to the shaft seal .Even with that thru hull closed I still had quite a bit of water coming from the propeller end of the shaft. I motored at less than 2000 rpm  for 90 minutes to the yard as I was not getting water from the thru hull. I did notice a slight groaning at 1000-1200 rpm. After 1200 rpm it stopped. The shaft and shaft seal were just a little warm, not at all hot like it was last week before the greasing to the seal. My mechanic thinks maybe the prop is out of pitch. Anyone have a similar experience?

[Bill Jarvis]

Did he explain how an over or under pitched prop would get the shaft hot?

 

Bill

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[Mohammad Bayegan]

The prop should not turn when sailing and engine is off.

If the prop is not turning ,pitch has no effect.

Marengo  B 49

Sent from my Verizon, Samsung Galaxy smartphone

[Walt Posner]

Good point. I think the shaft seal needed grease . After he did grease it it was no longer hot as it was before the greasing.

[Walt Posner]

It was turning when the motor is off and sailing. I put her in reverse and that did not stop the spinning. I do not think it ever engaged in reverse when the engine was off. Should I have put it in reverse with the engine running and then shut the engine?

[Walt Posner]

Correct. It may have been groaning/humming before but with the insulated panels to the rear engine area in place I may never have heard it. Now the panels are off and the aft cushions are in the main cabin so any noise is no longer muffled. I am still trying to figure out why putting the gear in reverse after I cut the engine did not engage and stop the shaft from spinning.

[Mohammad Bayegan]

If the prop turning regardless in forward or reverse when engine is off you have a clutch problem . 

The prop should not turn if engaged . 

[Mohammad Bayegan]

Bad clutch.

Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------

From: Walt Posner <wapo...@tampabay.rr.com>

Date: 11/16/16 12:22 PM (GMT-06:00)

To: benetea...@googlegroups.com

[Bill Jarvis]

Two or three things come to my mind.

1                     Is the shift linkage getting reverse all the way to engage? If it is then you have a worn clutch, replace it. If not adjust the linkage.

2                     Is the prop/shaft/ zincs properly balanced. If not some unwanted vibration may have caused the cutless bearing to wear.  Replace it.

3                     Is the prop shaft straight? Check with run out with a guage. Straighten or replace as needed.

Any of these could be cuasing excess side pressure on the shaft seal.

Bill

[Walt Posner]

Thanks. The mechanic was able to get it in reverse using the arm on the transmission. I am having the prop checked for balance. When I put her in reverse when sailing I heard no sound of the transmission going onto gear and saw the shaft still spinning. The zinc  is on the end of the shaft past the propeller attached horizontally so that is not likely the issue.

[Bill Jarvis]

Therefore it sounds like the gear shift linkage need adjustment.

 

That should be the easiest and cheapest solution.