Need help diagnosing stabilizer whine

[Russell Clifton]

I have developed a whine in my Naiad stabilizers. It takes a few minutes to develop after they are turned on, and is quite noticeable. I have changed the oil and installed a new filter. Also checked for loose fittings and changed the belt on the hydraulic pump.

Anybody experienced this before?

 

[Martin J]

Where is the wine from Pump, Gyro, etc. Also had a similar squeal /whine from the fan belt. A single fan belt is not enough for Naiads, they really need a double belt drive. I converted mine on my last boat to a direct drive from the front pulley , solved all my problems. Craig at Stabilized marine carries the parts. The only down part of the conversion is disconnecting the drive if you burst a hose or similar.

 

[Russell Clifton]

Martin, thanks for the reply. I changed the belt but it made no difference. After doing tons of research it appears that I have a cavitation issue, probably caused by a blockage between the pump and the reservoir. After looking at the system drawings in my owners manual it seems there is a strainer located inside the reservoir. I have sent off a email to Naiad but will need to wait until Monday morning for a reply.

 

[Civilitas]

I have not had a boat (or even operated one) with stabilizers. But I have worked on a fair number of similar hydraulic systems on vehicles, tractors, and construction equipment over the years - diagnosing problems, rebuilding pumps, hoses, racks, etc.

1) I interpreted - and maybe I was wrong - Martin's comments to imply the pulley shaft was overloaded in this application, and the noise might not be the belt itself, but accumulated wear on the shaft or bearings in the pump. So once it's worn enough to whine, a new belt isn't going to change things, and only rebuilding the pump and re-engineering the pulley so it didn't wear as quickly again. Or maybe I misunderstood his point.

2) You can isolate the noise using an improvised stethoscope (or a real one). A large screwdriver is adequate, or any solid rod like that. Put one end on various parts of the system (pump, at the stabilizer, etc.), the other on/next to your ear against bone. You will hear the noise transmitted through the system, but when you are at or close to the problem it will be very pronounced and obvious. This can neck down your problem considerably.

3) Again, I know nothing about the Naiad system in detail. I tried to find a diagram of the hydraulic circuit from a google search but oddly, no success. Maybe something is unique to this system, but it sounds really unlikely or at minimum weird to me there would be a blockage develop in the low-pressure part of the system between the reservoir and the pump. That is, overall, the very least stressed part of any hydraulic system.

4) Using some physical reasoning and your comment that the whine takes a few minutes to develop, it leads me to put wear and not blockage/constriction as a higher probability in a differential diagnosis. I say this because the pressure in the system is consistent after the first few revolutions of the pump onward. A cavitation/starvation issue should be apparent right away. What does change over a few minutes throughout the system is temperature. This has two main effects a) greatly thinning the fluid, and b) increasing tolerances in components from thermal expansion. Either of these, and especially the combination, can create a noise as metal now contacts metal unlike when cold. Of the P,V, and T in a fluid or gas system, it seem to me that since P and V (assuming the system is full and not leaking or you would have said so) have no effect on the noise, and T appears, to, I think about what that implies.

As I said, I've worked a bit on similar systems and PTOs, but all are unique and I don't know this system.

 

[Martin J]

I think Ciivilitas has the answer to locate the whine area and where it's coming from first to diagnose the problem.
My problem was strange with the belts when the belt is new one belt can just handle it but any minute slackening or heating of the belt when the engine room heated up, started the belt squealing. I installed forced air and extractors in the engine room, helped a bit but the conversion to direct drive pump solved it.

 

[Russell Clifton]

Civilitas:
Thank you very much for your insight. I agree that it could be air leaking in at the pump shaft. There is no kind of clutch on the pump so when the engine starts the pump starts rotating immediately, but it is bypassing the fluid back to the reservoir at a low pressure. It is not until the control switch is moved to on does pressure build in the system. Yesterday the whine did not begin until approximately 5 minutes after the switch was turned on.

I have a stethoscope and have listened to all the components, the noise is at the pump and in the outlet hose leaving the pump.

The reservoir is above the level of the pump and the fluid is gravity fed to the pump ( as all systems should be). Anything impeding the gravity fed fluid to the pump will starve the pump and it will cavitate, causing a whine.

So I believe either air is being introduced into the system, or the pump is starving for fluid

 

[Russell Clifton]

Still having issues with these stabilizers. I replaced the pump with a brand new one, but it did not help. I am now thinking I might remove the pressure relief valve located in the fluid conditioner. The operating pressure is within specs but maybe there is some dirt or build up keeping the valve from working properly. I have read that a pressure relief valve can cause noise in a system. Anyone ever removed one or had to service one of these from their Naiad stabilizers? Thanks.

 

[Martin J]

Hi Russell
Sorry to hear your still fighting the Naiad Whine. Why not try calling Craig Calkins at Stabilized Marine. He's a good guy very knowledgeable. He dispenses free advice readily. He has also in the past diagnosed and sent me parts and how to fit crib sheets with photos etc. He has supplied his info and parts freely to me and I cannot recommend him enough. He supplied stuff for my last boat (251's) and my current boat (252's)

 

[C lectric]

I see I am quite late to the party but I will post what I wrote regardless. Maybe it will trigger a thought.





No experience with these systems but I played millwright on plastic injection moulding machines for a time. They are one big hydraulic system. Air can get into the system on the suction side of the pump between the tank and the pump inlet. May mean the hoses are failing, fittings are loose or lost their seal although not likely about the thread seal.

Even the pump itself if gaskets and O rings in the pump body fail and they can.

One of the symptoms was the noise increase. Not only that but the machine would not operate properly since the air would turn the oil into one big accumulator, bubbles, so the pressure was not transmitted properly.

THis does not mean any oil will leak out unfortunately. But the vacuum under operation will pull air in to the system.

Can you open the reservoir and look into the oil? If you do have an aeration problem the oil will be cloudy. It may be best to let it sit overnight to allow any air to escape. Then next day start the system , GET and use A HELPER, and watch the oil.

Use a good flashlight to shine into the oil. Before the startup it will be clear, dark of course, but clear. If cloudiness appears there is an air leak. It may take a minute or so for the bubbles to appear. The cloudiness may appear as whitish. The bubbles will be so small that they will not easily be seen but they reflect the light from the flash so the oil will start to appear whitish.

Then of course the fun starts to find the source of the problem.

I wish you good hunting

 

[catalinajack]

Martin makes a good point about having to disconnect the pump to change belts. But, it is not a big deal. I am able to disconnect my pump in five minutes.

Where is the wine from Pump, Gyro, etc. Also had a similar squeal /whine from the fan belt. A single fan belt is not enough for Naiads, they really need a double belt drive. I converted mine on my last boat to a direct drive from the front pulley , solved all my problems. Craig at Stabilized marine carries the parts. The only down part of the conversion is disconnecting the drive if you burst a hose or similar.

 

[cardude01]

Stabilizer wine?


https://youtu.be/lfBDEeQGOJQ

Sorry. ?

 

[Russell Clifton]

Thanks to everyone for your reply's.
C lectric: the reservoir has a sight gauge on the side of it. I have watched it while the system is running and see no bubbles. I also read that you can apply some oil to the fitting while the system is operating and if there is a air leak the oil will be drawn into the leak and momentarily seal it off. That did not work either. The system uses 10w40 engine oil.
This has been a real challenge to figure out. Everything worked fine for the first two years we owned the boat until one day I accidently started the engines with the stabilizers turned on. Had never done that before. The noise started immediately.

The owners manual says that will not harm the system, but something sure happened.

The pulleys appear aligned by just looking at them but I am going to spend this weekend checking more closely and installing a new Gates heavy duty green belt.
Also, the pump is mounted to the engine stringer and is driven by a belt going to the engine harmonic balancer. Maybe there could be a vibration problem here so I might see if there is a way to insulate the bracket that mounts the pump to the stringer.

 

[C lectric]

I'm not so sure a sight glass would show the very fine bubbles I mentioned. We had sight glasses and it wasn't untill I opened the tank and did what I described that the cloud of them could be seen. The bubbles were so fine that they did not show individually.

Of course check for other sources but do what I suggested even if all it does is eliminate a suction air source as the problem.

In our shop the noise from the aeration could not be heard, too much other noise, as it came on very slowly over time. It was the quiet operation after the pump was resealed that tipped me off. I realize you can hear it ever the engine noise but just be sure.