Strange "ringing" sound when in gear

[First_Mate]

Anyone ever heard a faint, ringing sound when you put an engine in gear?

When I put the port engine in forward at idle speed, I hear a constant high-pitched ringing sound. Not like a squeak at all, more like the old "wet finger on the rim of the crystal glass" sound. Goes away with increased RPM's...

Doesn't do it on the stbd side. Also, this is a new development.

 

[annie]

Yep my Fathers 5.7 Mercruiser does that.... I put it down to the carb sucking air at low revs? You dont have 4 barrel Holley carbs by any chance?

 

[Sum Escape]

Could be "prop sing". A little info link:
http://www.marinelink.com/news/propellers-sing-do336986.aspx
My Cruisers 3870 had the issue after having the props tweaked for addition of a genset and dinghy (weight). Annoying, but not serious.

 

[Redhook98]

Sounds like new props to me....... My new ones did the same thing....

 

[fwebster]

Here is the most probably cause of the noise: It is typical for a Sea Ray to make a slightly different noise on the port than on the stbd side. That is because the same transmission is running in reverse on one side and in forward on the other in order to achieve counter rotating props. The gears have a different number of clutch disks for forward than reverse so you get a little hum or whine on one and not the other. Another factor in the different noise thing is that Sundancers with v-drives make the noise on the opposite side than a DB with straight inboards.

 

[First_Mate]

Thanks for the replies. They are reconditioned props...

Glad to hear it doesn't sound like a serious problem such as bearing or shaft seal or some such...

 

[Total Eclipse]

Do you hear the sound when your not in gear, or when the engine keys are on and you haven't start the engines?

 

[First_Mate]

Do you hear the sound when your not in gear, or when the engine keys are on and you haven't start the engines?

No. Only port engine in forward at idle speed.

 

[alnav]

I had a ringing sound and it turns out to have been the ship's bell, which in my case is mounted under the helm seat.


It was by no means obvious but at certain speeds including idle, the vague ringing sound was being caused by the bell vibrating. I only found it when the dog started going into the area under the seat for refuge in heavy seas. Tightening the nut at the top caused it to go away.

 

[HUMPH]

Here is the most probably cause of the noise: It is typical for a Sea Ray to make a slightly different noise on the port than on the stbd side. That is because the same transmission is running in reverse on one side and in forward on the other in order to achieve counter rotating props. The gears have a different number of clutch disks for forward than reverse so you get a little hum or whine on one and not the other. Another factor in the different noise thing is that Sundancers with v-drives make the noise on the opposite side than a DB with straight inboards.

Frank, my 410 picked up a comforter on the port prop and now has a distinct high pitch noise. It's not too loud but it is there and was not before picking up the comforter. Any ideas what this bedding could have done to my running gear? I seem to run just fine but the sound is disturbing.

 

[fwebster]

Ken,

That one is a little out of my area. Most folks down here keep the bedding in their boats (sorry, couldn't resist). We do hang large discarded lines and lost anchor rodes occasionally, but no one has had any lasting effects. I would suggest that you service your transmissions and wash the filter in the noisey side in a separate container so you can catch whatever comes out of it. Check the solids, if any with a magnet and try to see how much of it is ferrous metal and how much is non-magnetic. Of the non-magnetic, note how much is gold in color and how much is silver. That will give you an idea if you have a bearing, a gear or part of t he case or clutches wearing.

 

[davefin]

Have 350 HP MPI's, had the same thing a couple of times last Summer while docking. A harmonic sound, mostly when slow idle in gear. The wet finger and crystal glass was a good comparison. Have not experience it again. Puzzling!

 

[HUMPH]

Ken,

That one is a little out of my area. Most folks down here keep the bedding in their boats (sorry, couldn't resist). We do hang large discarded lines and lost anchor rodes occasionally, but no one has had any lasting effects. I would suggest that you service your transmissions and wash the filter in the noisey side in a separate container so you can catch whatever comes out of it. Check the solids, if any with a magnet and try to see how much of it is ferrous metal and how much is non-magnetic. Of the non-magnetic, note how much is gold in color and how much is silver. That will give you an idea if you have a bearing, a gear or part of t he case or clutches wearing.

Thanks Frank. I wonder if it could have put a strain on my cutlass bearing though??? I am tearing into the engines this weekend to remove the aftercoolers to have them dipped and change the engine oil, maybe the tranny oil will be done as well!