Weird screeching noise

[OldDan1943]

Trace the shaft fwd from the packing gland. If you have one, you will see it.

 

[Skipper41]

Cutlass bearing

I had a similar experience. It turned out to be the cutlass bearings on my Nordic Tug.

 

[Steve1.0]

+1 for the carbon brush.
Happened to me while delivering a new Back Cove 41 to a boat show. My first thought, transmission lost its oil. Thankfully, adjusting the brush stopped it.

 

[IWAB]

Screeching sound from engine room.

I had a similar sound one day when going out to exercise my For Lehman’s. I lost have NAID stabilizers. Turns out, after checking belt tightness, the double belted hydraulic pump on my starboard engine was loose, and upon tightening, the sound disappeared.

Check to be sure your belts are properly adjusted.

 

[sbman]

Thanks for all the responses. I am going to replace the cutless bearing. Does anyone have experience doing that?

If you plan to do it yourself, the 'Strutpro' makes it an easy job. I purchased one to work on my cutlass bearings and I did it without even having to remove the shafts. Theoretically it could be done underwater by a diver. I've now used it on several boats at the boat yard, helping people out.

I detail it's use here:

https://www.trawlerforum.com/forums/showpost.php?p=872086&postcount=45

 

[Steve1.0]

" I did it without even having to remove the shafts."


sbman,That shaft pro tool looks great,but how do you get the new bearing on the shaft if you don't at least back the shaft out partway?

 

[rgano]

" I did it without even having to remove the shafts."


sbman,That shaft pro tool looks great,but how do you get the new bearing on the shaft if you don't at least back the shaft out partway?

Slide it along the shaft from the aft end where the prop has been removed. If you have more than one bearing on the shaft, you replace the forward one first by sliding it through the aft bearing. A clean shaft and a bit of dish soap can help.

 

[sbman]

Slide it along the shaft from the aft end where the prop has been removed. If you have more than one bearing on the shaft, you replace the forward one first by sliding it through the aft bearing. A clean shaft and a bit of dish soap can help.

That's correct. I pushed a new bearing into the aft strut (which pushed the old one forward and I split it with an angle grinder for removal), I then pushed a second bearing into the aft strut whish pushed the first new bearing forward I then pushed that new one into the forward strut. Shaft stayed in place the entire time. You definitely need the shaft to be clean so you can slide the bearings around.

 

[lanceolson]

Thanks all...found bad cutless brg...rubber came apart...shaft ok

 

[jimL]

Updated links are below.

We have a new to us 2001 Grand Banks Europa 52 with Cat C9 engines and approximately 3300 hours. The boat was surveyed on the hard in March and in the water in April.

We have an unusual sound that starts around 1400 rpm and disappears at 1650 rpm or so. I wouldn’t refer to it as a screech, but more as a low frequency moan. We checked the engine room which is mid ships, and the noise appears aft of the engine room and is more pronounced in the aft cabin which is between the engine room and lazarette.

When we surveyed the boat, the cutlas bearings looked fine and we were able to rotate the prop shafts as appropriate.

Here are links to two videos with sound. You will have to listen carefully for a low frequency moan. When the moan starts there is no discernable difference to acceleration or anything else. The alternators are charging, and it seems to come from aft of the engine room.

Any ideas?

Here are the two links:

https://youtu.be/5ndXttJj_aY
https://youtu.be/kEXwRhvtdWA

Thanks,

Jim L

 

[wkearney99]

Any ideas?

Here are the two links:

Better to use something like youtube, as it wouldn't require any login. You can post a video as 'unpublished' and it'd still be visible if someone knows the URL (vs publicly listed or private and locked to only specific users).

 

[RT Firefly]

Greetings,
Mr. jL. A case of Billy Idol?

A friend's uncle had an affliction of Patsy Cline a number of years ago. He was crazy...

 

[jimL]

Thanks Bill and RTF - I updated the links on the last post of the previous page.

JimL

 

[lanceolson]

Thanks all. Replaced 6 cutless bearings cost $8,000 :-{

 

[BruceK]

Greetings,
Mr. jL. A case of Billy Idol?

A friend's uncle had an affliction of Patsy Cline a number of years ago. He was crazy...

Good examples of a "weird screeching noise".
Our sulfur crested cockatoo is the chief emitter of "weird screeching noise' here. Listen to this, pretty cute too, eh?

To the OP, apologies for the intrusion, congrats on the fix, 8K, ouch!

 

[jimL]

While out with my better half driving, I went to the two struts on each prop shaft and listened to the noise using a screw driver touching the interior strut assembly and my ear on the other end. The noise was coming from the aft starboard strut. We did a short haul and replaced the cutlass bearing which was not worn, but replaced it anyways and the noise is still there. I also replaced a few undersized anodes. Any ideas?

Thanks much, JimL

 

[Cigatoo]

I have the same “screeching noise” every year mid to late summer. Have a diver clean the barnacles off of the running gear and the noise goes away. Start with the simple stuff

 

[MVDarlin]

Maybe you picked up a crab pot and the line / cable got wrapped around the shaft. Check the shaft for residual debris.

 

[JTN Grand Banks]

Noise?

Start with the easiest solution. Belt tension/wear. Other source could be a turbo charger bearing ( hope Not) Let us know what you find

 

[jimL]

Thanks for the suggestions.

The noise is not related to the engines - the noise is aft of the engines near the props and rudders. I did scrape the barnacles off all of the underwater gear, changed the aft starboard cutlass bearing and the noice is still there. and it's only between about 1400-1650 rpms.

Jim

 

[Bacchus]

Jim
Have you/others checked shaft alignment?
I know of another boater that had a squeel that was related to cutlass brg but it was alignment related as a replacement didn't cure the noise.
His was bad enough it actually worked the cutlass out of the housing. Bent strut was ultimately the root cause.

 

[OldDan1943]

Thanks for the suggestions.

The noise is not related to the engines - the noise is aft of the engines near the props and rudders. I did scrape the barnacles off all of the underwater gear, changed the aft starboard cutlass bearing and the noice is still there. and it's only between about 1400-1650 rpms.

Jim

Jim, you have verified the screeching is not coming from the shaft grounding straps?

 

[DennisB1]

I have grounding on the two propeller shafts on my 3208tas. They both mount on the same side port side. The shafts rotate in opposite directions. The one where the shaft rotation pushes on the bronze rider and squeals at times. A little lubrication stops the squeal. The one that is pulling rather than pushing never squeals.

Along with measuring temperates I found using a wooden dowel 20 to 30 inches long to help ID strange noises. Put the dowel on different parts, water pump, alternator and so on and touch the other end to your ear and listen to the local sounds. (engine running) works great trying to find problems.

Belts squeal like you described if you had a sudden load to say powering an inverter to run a microwave. Its about a 120 amp load on my alternator need tight belts to prevent.

 

[wkearney99]

Along with measuring temperates I found using a wooden dowel 20 to 30 inches long to help ID strange noises. Put the dowel on different parts, water pump, alternator and so on and touch the other end to your ear and listen to the local sounds. (engine running) works great trying to find problems.

That's the same idea as long screwdrivers or socket extensions also help to pick up vibration noises from specific sources. Hold one end against your head, just at your ear canal, and the other on the suspected location. Much easier to pinpoint noises without the background of all the other sounds. But you're more likely to find dowels in much longer lengths. And maybe pull double-duty as a story pole to measure fuel tank level (just keep the messy end away from your head!).

For a car it's often useful to have a mechanic's stethoscope, as they're good for isolating vacuum leaks. Not "as useful" on a boat but still a good troubleshooting tool when it comes down to finding oddball noise sources.

 

[C lectric]

I've used a mechanics stethoscope for years on the boat, cars and at work.

I have used dowels and screwdrivers also but the stethoscope is FAR safer.

You can pinpoint the noise from a failing , not yet failed, bearing or a loose vibrating part that you can just barely hear as not right but the sound is not yet strong enough to zero in on the source without a helper.

The other tools will work but do not amplify as the stethoscope does and if you slip you will likely only damage/destroy the stethoscope.


Have you checked the shaft alignement? If the shaft is off centred to far in the cutless bearing it could cause a squeal. Engines can compress the mounts so they settle lower than when new which can cause the shaft to drop pinch at the bottom front and rise pinch at the rear of the cutless.

Long shafts with two cutless brgs. are more difficult to align. I've never done it but have done my boats single cutless shaft. Still a bunch of work.

 

[wkearney99]

Like any tool, if used without care there's definitely risks. To give a listen, via bone conduction, to a source using a dowel/screwdriver/whatever you're definitely taking a greater risks since you're, by necessity, going to turn your gaze away from the point where you're placing the business-end of the implement. Plan accordingly against risks from something slipping. That includes the tool, obviously, but yourself too if you get careless trying to move the tool around without looking, and end up slipping TOWARD the problem.

 

[jimL]

Prop singing - as it's referred to in the prop industry occurs when the leading edge of the prop is dulled to a blunt surface and not a 45 degree surface. Thanks for challenging me on this. I was able to find information on line and now the props are at the prop shop for a tune up.

The prop shop owner asked if the noise sounds like a person taking a wet figure around a crystal wine glass - and there it was! Thanks all.

JimL