[C320-list] Vibrations at certain RPM Range

[Scott Lagerquist]

John,

On my past Catalina 30 I had this issue and the cause was the primary fuel filter was starting to clog.  When the engine is at lower reps and not getting a good fuel flow it started to rattle. 

This may or may not be your issue but I thought I’d at least respond in the event it is.  Another possibility is one of your cylinders has a fuel issue.  Could be clogged injectors or a problem with the lift pump.  

A potential troubleshooting method for is to see if the engine stalls at idle.  If your idle is normal I’d rule out fuel flow.

Good luck,

Scott Lagerquist 
1994 C-320, #39 
Sea Esta 
San Diego CA

Sent from my iPhone

> On Aug 6, 2019, at 8:18 AM, Arthur Gates <argates2nd at comcast.net> wrote:
> 
> My stern ladder rattles against the top of the stern pulpit at times. 
> #186
> 
> Sent from my iPhone
> 
>> On Aug 6, 2019, at 10:38 AM, John Meyers <jcmeyers7 at gmail.com> wrote:
>> 
>> 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