[C320-list] Vibrations at certain RPM Range

[kskis at aol.com]

John:  I have a similar issue from 1800 to 2500 rpms.  But only in forward gear not in neutral or reverse.  I've had it since purchase 2 years ago.  I was told it was a prop issue so I had the prop serviced.  Also replaced the cutlass bearing.  No change.  Still thinking it's the prop and need to find a good prop shop to do some magic on it.  Or change the prop and see if the noise changes. My engine runs very smoothly at all rpm's.  If yours does it in neutral I'm guessing it can't be a prop issue.  Neil Kornblatt 2004 Harmony #973


-----Original Message-----
From: John Meyers <jcmeyers7 at gmail.com>
To: C320-List <C320-List at catalina320.com>
Sent: Tue, Aug 6, 2019 10:38 am
Subject: [C320-list] Vibrations at certain RPM Range

Starting about 3 weeks ago the boat is making a loud racket when the engine
is revving between 1500 and 2000 rpm. mostly in the rear of the boat but I
cannot pinpoint the source. This occurs both in gear and in neutral so not
suspecting shaft alignment. I suspect that it is some harmonic thing. All
motor mounts look good and solid and well attached with over a quarter inch
between the metal parts. I have check both feeling and/or removed just
about every thing in the lockers like spare prop, spare anchor, propane
tank, and other items that might be shaking while the noise is occurring. I
have felt the fuel tank and engine and nothing feels different than when
the noise is not noticeable. I have even gone below the boat and felt the
shaft prop cutlass, rudder and all seem solid. The shaft and cutlass
bearing were replaced a couple years ago. I have checked the steering
mechanism.

To explain the noise/clatter it sounds like a loose hatch, door, or
equipment is shaking.

At low revs and higher revs the noise is not there.

Has anyone ever had this problem or know someone that has/had this problem?

Thanks for all your help in past, present, and future. I rely on the
questions and answers this list provides.

John Meyers
Wind Chime 1997 #406
Muskegon, MI