[C320-list] Engine noise

[Jeffrey Hare]

Jim,

  If you do have a PSS and notice this sound, go down below and see if the
PSS is warm, and burp it to see if there's any air in there.  If it has
plenty of water in it, then it's less likely to chatter.  Without water, it
can chatter under the right circumstances.

  Another possibility is that a shaft zinc has loosened up and slid down
against the cutlass.

  Final thing I could think of is that if you have a bronze shaft and the
alignment is not quite perfect, you could be experiencing shaft whip when
the right combination of prop loading and RPM are hit.  Worn engine mounts
would help make this worse.

FYI: As for the RPM, 2900-3000 is really the Yanmar's sweet spot on the
power curve and as Jon said, can run for days at a time there.  Contrary to
what seems intuitive, running the engine at lower uses significantly more
fuel, not less as would be the case for a gas engine.  (From a study looking
at Diesel-alone vs. diesel-electric efficiency)

-Jeff 

-----Original Message-----
From: c320-list-bounces at catalina320.com
[mailto:c320-list-bounces at catalina320.com] On Behalf Of Stanley Rogacevicz
Sent: Monday, July 16, 2007 8:34 AM
To: C320-List
Subject: Re: [C320-list] Engine noise

Jim,
   Again IF you have a PSS I'll just state Jon's post a bit differently - In
following seas - I sometimes got a horrible sounding vibration from the PSS
when really trying to make some time surfing the waves relieved by a
throttle adjustment.
   Also if you are heading - into - big seas that are sending foam to your
stern you can sometimes hear a different 'growling' sound as the Prop
Cavitates - fixed, folding, whatever, PSS or not.
Stan

>>> <jonvez at comcast.net> 7/16/2007 8:19 AM >>>
Jim,

Could be cavitation from the prop, which can happen in rough seas or if the
boat is outrunning the rpms. If you have a PSS, it can chatter when bouncing
around sometimes. I've had this happen and have done what you did...ease
back the throttle, make sure everything else is okay and continue....

Regards,

Jon Vez

-------------- Original message --------------
From: "Jim DeLong" <jdelong3 at neo.rr.com> 

> Wondered if anyone else has experienced this engine noise? 
> 
> While in the ocean a couple of days ago, trying to outrun a squall, a 
> crew member cranked up the RPM's to 3000. More that I'm normally
confortabe with.
> 
> After 15 minutes or so, the normally smooth engine (Yanmar 27 HP) 
> began to sound like metal grinding. Pulled the RPM's bact to 2200 and all
was well.
> Cranked it up again and after 15 minutes it started again. No other 
> symptoms at all. Ran well but just sounded funky. In port yeaterday we 
> started the engine and ran it up to 3000. Could not get it to do it again.
> 
> Thought it may be from the transmission or a slipping shaft, but the 
> prop seemed to turn just fine.
> 
> Anyone experience this one? 
> 
> Thanks,
> Jim DeLong #453
> 
>