Shringing sound under acceleration

[glambx]

Hello again everyone!

I've got a Cal 2-46 with a Perkins 4.236, which seemed to be running well, but has started making an alarming shringing noise (like grinding bearings at high speed) only during acceleration. Once the engine reaches target RPM, the noise stops.

Oil pressure reads 50-75PSI depending on RPM.

I've tried googling but apparently I'm the only person in the world who uses the term "shringing" ... and it's the only word I can think of to describe it.

Any ideas?

[Boatyarddog]

Originally Posted by glambx

Hello again everyone!



I've got a Cal 2-46 with a Perkins 4.236, which seemed to be running well, but has started making an alarming shringing noise (like grinding bearings at high speed) only during acceleration. Once the engine reaches target RPM, the noise stops.



Oil pressure reads 50-75PSI depending on RPM.



I've tried googling but apparently I'm the only person in the world who uses the term "shringing" ... and it's the only word I can think of to describe it.



Any ideas?

I'll take a guess that if you watch your packing gland, during acceleration, you may see it being twisted to one side.
The shaft maybe touching the gland during acceleration.
This may be due to improper alignment, or compressed engine mounts, possibly loose mountings.
The engine will torque to one side during acceleration.
Check the shaft alignment.
If you have an infrared, thermometer, watch for heat buildup during this time, at the packing gland.
That could confirm that possiability.

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[glambx]

Originally Posted by Boatyarddog

I'll take a guess that if you watch your packing gland, during acceleration, you may see it being twisted to one side.
The shaft maybe touching the gland during acceleration.
This may be due to improper alignment, or compressed engine mounts, possibly loose mountings.
The engine will torque to one side during acceleration.
Check the shaft alignment.
If you have an infrared, thermometer, watch for heat buildup during this time, at the packing gland.
That could confirm that possiability.

Sent from my iPad SV Cloud Duster

Thought about it, but unfortunately it makes the noise even in neutral, when the shaft isn't; spinning.

I will take a look to make sure the accessory pulleys aren't hitting anything though.

[NoTies]

Slipping alternator belt?

[Boatyarddog]

Possibly drive plate,cracked,springs can become dislodged and get trapped near a rotating part.
Start with the easiest to see
Remove those belts temporary, noise is gone? Then it's in the belting.
If not, listen closely to locate the noise more precisely.


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[SkiprJohn]

Originally Posted by Boatyarddog

Possibly drive plate,cracked,springs can become dislodged and get trapped near a rotating part.
Start with the easiest to see
Remove those belts temporary, noise is gone? Then it's in the belting.
If not, listen closely to locate the noise more precisely.


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That's my guess too. Damper plate between engine and transmission. In order to know for certain I'd put a stethoscope on that area and have someone accelerate to see if that is the locale. Stay clear of the shaft and all other moving parts while you're down there.

Good thing the 2-46 has a nice big engineroom.

[glambx]

Sadly I'm back shoreside for the next month, but I'm trying to direct the boat yard on what to check while I'm gone. If they don't solve it I'll be sure to go through this list.

No one's suggested the main bearing yet, which makes me happy.

I'll keep updates posted, and thanks everyone.

[Compass790]

If you have a magnetic drain plug check for metal particles in the oil & I hope for your sake there is none. Probably unlikely if you have good oil pressure tho.
Just a thought

[SkiprJohn]

Originally Posted by glambx

Sadly I'm back shoreside for the next month, but I'm trying to direct the boat yard on what to check while I'm gone. If they don't solve it I'll be sure to go through this list.

No one's suggested the main bearing yet, which makes me happy.

I'll keep updates posted, and thanks everyone.

Wouldn't that be more of a knock instead of a shring?

[Fiveslide]

I had an old Cummins that started "shringing", it was a loose alternator pulley. Kinda sounds like a bell ringing combined with some metal on metal grinding?

When accelerating it would spin on the shaft, ring, it was quiet at all other times.

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[jkishel]

Get the belt(s) off and check all belt driven rotating components; alternator, water pump(s), etc.

[SkiprJohn]

Originally Posted by jkishel

Get the belt(s) off and check all belt driven rotating components; alternator, water pump(s), etc.

I think this will at least let you know if those are the culprits. A failing bearing in a water pump or alternator would make that type of noise too but would be consistent.

I take it to mean that it only happened at engine rpm acceleration which could mean that a belt is slipping on a drive pulley until the pulley comes up to speed. My tractor does that until the alternator pulley starts to turn because I have a loose belt.

Watching your ammeter when accelerating might tell you what's happening at your alternator.

[Compass790]

With a plain bearing on the crankshaft definitely yes a knock but if he has ball or roller bearings they can maybe squeal ( or shring) a bit. As I said it's unlikely but transmission oil should be checked as well if the other faults dont prove to be the cause.