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-   -   Loud whine in driveline at low RPM (http://www.sailnet.com/forums/atomic-4/58447-loud-whine-driveline-low-rpm.html)

straitdave2 09-28-2009 02:03 PM

Loud whine in driveline at low RPM
 
I have a 1974 A4 in an Ericson 35that runs great and seems to have few problems except when I am in forward at lower rpm and this 'whine' or squealing noise starts up. It doesn't seem to be coming from the transmission but more or less from behind the transmission (even from behind the stuffing box). When the boat was recently out of the water I checked the cutlass bearing and everything seemed OK there. When I increase the rpm's to cruising rpm the noise goes away entirely. Anybody have any ideas??

Thanks,

David

timebandit 09-30-2009 04:00 PM

Maybe a bearing at the other end of the shaft?

Faster 09-30-2009 04:18 PM

We had a similar "whine" that eventually disappeared.. then the stuffing box drip rate increased. Repacked the stuffing box and now that whine is back at the same rpm.. so I suspect that's the source.

It's not a big issue for us as we rarely travel at that particular rpm, I just hear it briefly as we're slowing down to enter our marina. Beyond the temporary noise, the stuffing box drip rate is fine as is the running temperature.

Northeaster 09-30-2009 07:57 PM

I have the same issue, and the whine starts decreasing around 2700 rpm and stops completely when I get up over 3000. Doesn't do it in neutral or reverse, just in forward.

I have loosened the stuffing box nut off a couple of turns, so it was leaking alot of water, t osee if that was the problem. However it still had the whine. The stuffing box normally doesn't leak much but is never hardly war,m to the touch, let alone hot, so it seems OK.

MrkSchmt 09-30-2009 08:54 PM

There was discussion about this whine on the Moyer Marine message board a few months ago. From what I remember, many people had a whine at low RPM, myself included, and no one seemed to know what it was. The general consensus was that the whine is commonplace and not indicative of anything bad.

Mark

Boasun 10-02-2009 12:25 PM

Grease your packing gland. And see if the noise goes away...

Northeaster 10-02-2009 06:08 PM

Boasun- Since the OP and I have a similar "whine", can you give a bit more detail about Greasing the packing gland/ stuffing box. I have fairly new traditional flax, that comes pre-greased. I wasn't aware that you could / should add anymore grease.

If there is no grease fitting, what do you do, Take the nut off and quickly swab some grease in there? What type of grease?

At least in my case, I loosened the nut off until lots of water was flowing out, and the nwent for a motor. It still whined, so I thought that woudl have ruled out the packing gland.

CalebD 10-03-2009 01:00 AM

Umm.
I would not use grease or oil in the packing gland of the stuffing box. It is designed to be lubricated by water, not grease or oil. This is why a few drips of water while the shaft is in motion is normal - water is lubricating AND cooling the joint.
I once made the mistake of putting some oil in my stuffing box. The old packing quickly decomposed and we had a bigger problem - a fast leak at the rear end, after a period of inattention the cabin sole (floor) had 6" of water above it. The laws of 'unintended consequences' come into play when you mix stuff that is not supposed to be there with stuff that is. The residual flax packing material thoroughly gave up the the ghost with the addition of hydrocarbons (oil) and sea water.
With all due respect to Capt. Boasun the best authority and tutorial on stuffing boxes on the net is: Re-Packing A Traditional Stuffing Box Photo Gallery by Compass Marine at pbase.com

Personally, I do not believe that the noise you are hearing is from the stuffing box. I will bet even money that your tranny needs a slight adjustment. I have to shift slightly into the range of Reverse to get the prop to stop spinning altogether and then there is a slight whine as Reverse is partially engaged. If I do not back off towards Reverse the prop keeps spinning slowly in forward and there is no whine. There is no 'click' to define neutral on our boat and knowing when the prop is not spinning is a bit of an art more then a science.
I respect all the other suggestions here in that:
- engine/shaft alignment
- cutlass bearing
are all possible culprits.
I will add one more possible problem: barnacles or growth. Is your prop clean?
I am not an expert in A4 transmissions (yet) so I refer you to: Moyer Marine Atomic 4 Community - Powered by vBulletin
for further guidance.
Good luck and enjoy the whine.


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