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Old 06-03-2021, 17:19   #1
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Volvo Shaft Vibration

Hi Folks

We bought current boat back in 2017 - i've been always aware that motor vibrates at idle. I've asked previous owner (who was original owner from new), and he advised that he had mechanic look at it during warranty and he was advised that this is normal.

Boat is Beneteau 331 and motor is MD2030.

Last summer (I'm on Great Lakes), we were motoring for few hours as we had no wind so as my usual routine, I check on everything and when I took a peak at dripless when motoring (idle fwd - and never looked at the shaft while motoring before), I've noticed that the shaft vibrates a lot. Once I raise RPM motor and shaft are perfectly smooth.

Shaft at idle fwd (RPM about 670)
  • Disregrad knocking as that ws loose cable
Motor at idle (RPM about 670)
Shaft going fwd (RPM over 1k)
Motor going fwd (RPM over 1k)

I did not play with RPM to check at what RPM vibration goes away (bummer but I did not think of it) - will need to check in couple months once back in the water.

Before end of last season I had diesel mechanic look at the motor/shaft. He said mounts are fine and shaft is spinning true (no alignment issues). He advised that motors with odd number of cylinders have a tendency to vibrate a lot, raised the RPM to about 750 which took some of the vibration away. Lastly told me as last measure to check if there is any play when I pull on the prop. If there is any play he suggested to replace cutlass bearing. So at haul out I checked the shaft/prop and there is absolutely no play - it's solid.

So I honestly don't know if I should worry about it or not - in my opinion it's too much vibration, but I'm not diesel guy. Original owner told me that motor has been vibrating more than he would expect since new and when he had it looked at during warranty was advised that it's normal. But he never thought of looking at the shaft while idling fwd.

Also just reading this weekend looking like spec for this motor calls for 850 +/-25.

Let me know your thoughts.
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Old 06-03-2021, 17:54   #2
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Re: Volvo Shaft Vibration

Firstly get a hand held rev counter and make sure it is calibrated correctly ,the engine is idling far to slow ,do not adjust the throttle stop ,you must adjust the governed set set screw to about 825 plus but under 1k if not a marked improvement change to poly flex mounts ,done this often as generally original mounts are to old and to soft ,plus odd number diesel cylinder is always smoother if 4strokes hence 3and 5 and 9 and 11 cylinder diesels these are in line engines ,.⛵️⚓️
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Old 06-03-2021, 17:56   #3
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Re: Volvo Shaft Vibration

Ps my 5lw Gardner idles at450 rpm smooth as glass .⚓️⛵️
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Old 06-03-2021, 17:59   #4
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Re: Volvo Shaft Vibration

My volvo D130 is a shaky motor
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Old 06-03-2021, 18:17   #5
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Re: Volvo Shaft Vibration

Quote:
Originally Posted by szymek View Post
Hi Folks



We bought current boat back in 2017 - i've been always aware that motor vibrates at idle. I've asked previous owner (who was original owner from new), and he advised that he had mechanic look at it during warranty and he was advised that this is normal.



Boat is Beneteau 331 and motor is MD2030.



Last summer (I'm on Great Lakes), we were motoring for few hours as we had no wind so as my usual routine, I check on everything and when I took a peak at dripless when motoring (idle fwd - and never looked at the shaft while motoring before), I've noticed that the shaft vibrates a lot. Once I raise RPM motor and shaft are perfectly smooth.



Shaft at idle fwd (RPM about 670)
  • Disregrad knocking as that ws loose cable

Motor at idle (RPM about 670)

Shaft going fwd (RPM over 1k)

Motor going fwd (RPM over 1k)



I did not play with RPM to check at what RPM vibration goes away (bummer but I did not think of it) - will need to check in couple months once back in the water.



Before end of last season I had diesel mechanic look at the motor/shaft. He said mounts are fine and shaft is spinning true (no alignment issues). He advised that motors with odd number of cylinders have a tendency to vibrate a lot, raised the RPM to about 750 which took some of the vibration away. Lastly told me as last measure to check if there is any play when I pull on the prop. If there is any play he suggested to replace cutlass bearing. So at haul out I checked the shaft/prop and there is absolutely no play - it's solid.



So I honestly don't know if I should worry about it or not - in my opinion it's too much vibration, but I'm not diesel guy. Original owner told me that motor has been vibrating more than he would expect since new and when he had it looked at during warranty was advised that it's normal. But he never thought of looking at the shaft while idling fwd.



Also just reading this weekend looking like spec for this motor calls for 850 +/-25.



Let me know your thoughts.


I agree with Searles observations, the idle rpm should be 850, plus or minus 25 rpm but often mechanics drop the idle rpm to reduce clunky gear shifts.
One of the reasons for bad vibration at idle can be poor distribution of load across the 4 mounts and itís quite difficult to get this right. If one mount is adjusted poorly for height, the engine shares the load only between diagonal mounts so two are doing the heavy lifting and the other two are having a bit of a bludge and the engine can rock on the two mounts that are carrying the most load.
Volvo 2030 has heavier load mounts on the rear of the engine and lighter load mounts on the front, something to discuss with Isoflex if you decide to go with that idea.
Pete.
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Old 06-03-2021, 19:04   #6
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Re: Volvo Shaft Vibration

Turn the idle up to to 850-900, as long as the shifting isn’t too harsh. Looks good in gear at cruising RPM.

The 2030 on the stand in my garage jumps around at low RPM too.
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Old 07-03-2021, 18:20   #7
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Re: Volvo Shaft Vibration

Thanks for your feedback - I continued to search online and it appears that many people complain about the Volvos and shaking - but i don't see anyone talking about the shaft. When I first noticed it, my biggest concern was dripless and/or cutlass bearing failing as the shaft vibrates a lot. But by the looks of it she has been running like that for many years (most likely).

As soon as we launch in May, i'll raise rpm to 850. And out of curiosity I will ask the mechanic that looked at the boat whether he used rev counter or just went by rpm gauge.

Maybe I started over thinking this
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Old 09-03-2021, 23:19   #8
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Re: Volvo Shaft Vibration

Suggest checking both rear engine brackets for cracking. Wrapping a mooring line around the prop has been known to cause one to break and consequent vibration and noise. If bracket is broken also have shaft allignment checked at next haul out.
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