[C320-list] New Engine Mounts

Thu Jun 26 18:01:09 PDT 2008

I made a chart to log the vibration level versus rpm for my Yanmar 3GM30F. 
This was done at the dock in neutral to be used as a base line.  Then I did 
the same thing when motoring under power.  A few new very minor vibrations 
appeared at new rpms and some reinforced those measured at idle  Overall, 
the newly installed Autoprop did not introduce any serious new vibration on 
my boat.

The boat is a 2002 model with low engine hours so I assume the engine mounts 
are in good shape.

This would seem like a good test to see what vibrations arise from the 
propeller/shaft and which are resident at idle.

Bob Sloat
Savannah Hull 894

----- Original Message ----- 
From: "Kirk McCullough" <kirk.mccullough at telus.net>
To: <C320-List at Catalina320.com>
Sent: Thursday, June 26, 2008 6:56 PM
Subject: Re: [C320-list] New Engine Mounts

> THe engine rattles around on the mounts, make a nasty noise etc, does this 
> even if the shaft isn't turning , so it seems its not the shaft hitting 
> the hull, just the shaking of the motor,alt like its going to stall or 
> something.
> ----- Original Message ----- 
> From: "Martin Raphael" <mraphael at q.com>
> To: <C320-List at Catalina320.com>
> Sent: Thursday, June 26, 2008 7:25 AM
> Subject: Re: [C320-list] New Engine Mounts
>
>
>> Balance of the prop (flex-o-fold) and condition of the shaft (stainless 
>> steel) could be contributors and I plan to check those out next.  I don't 
>> think they are the issue, as I had no problems at higher RPMs and I would 
>> think shaft and prop problems would be worse at greater speeds.  When you 
>> say "shakes" I wonder what that mean?  In my case, with the new mounts 
>> the movement is extreme and the shaft actually knocks against the tube .
>> ----- Original Message ----- 
>> From: "Pat Moriarty" <patm at psiurethanes.com>
>> To: <C320-List at Catalina320.com>
>> Sent: Thursday, June 26, 2008 5:24 AM
>> Subject: Re: [C320-list] New Engine Mounts
>>
>>
>>> Only one thought, are you sure about the shaft and prop being true and 
>>> balanced?
>>> Mine only shakes at dead idle when starting from sitting still or 
>>> changing directions but at 1000 RPM no shake, 1994 Perkins 600 hrs 
>>> original mounts.
>>>
>>> Pat #130At 07:55 PM 6/25/2008, you wrote:
>>>>I just replaced my non-stock engine mounts with the stock Perkins mounts 
>>>>per the thread below.  To my great distress, the engine now vibrates 
>>>>wildly, to the point that the shaft bounces against the shaft tunnel 
>>>>when in gear.  I had hoped that the softer stock mounts would solve a 
>>>>long-lasting vibration and noise issue I have been experiencing.  Now my 
>>>>mechanic says the real culprit may be in the valves and they will be 
>>>>checking that out tomorrow. He says he has encountered 2 other Perkins 
>>>>that have serious valve rocker wear, and that this can cause the 
>>>>vibration.  Have any of you heard of this problem or experienced it 
>>>>yourselves?  Right now I'm feeling rather foolish for having invested a 
>>>>huge amount of money in new mounts when those may not have been the 
>>>>culprit.  BTW, mine is a 94 Perkins M30.  So let this be a caution 
>>>>before blindly switching out motor mounts.  I may have to just go back 
>>>>to the old mounts and live with the annoying but tolerable vibration.
>>>>Martin Raphael
>>>>Rhapsody #108
>>>>----- Original Message ----- From: "Martin Raphael" <mraphael at q.com>
>>>>To: <C320-List at Catalina320.com>
>>>>Sent: Sunday, June 01, 2008 7:16 PM
>>>>Subject: Re: [C320-list] New Engine Mounts
>>>>
>>>>
>>>>>Just a thought here...the engine will vibrate the same way in relation 
>>>>>to RPM whether you have old or new engine mounts, wouldn't it?  Engine 
>>>>>mounts will affect how that vibration is transmitted to the hull, and 
>>>>>thus what we hear or feel.  Stiffer mounts will transmit more directly 
>>>>>to the hull...softer mounts will absorb vibration.  So I wonder if 
>>>>>Mike's new mounts were actually "softer" than the worn mounts he 
>>>>>replaced.  I say this because some years ago (2003) I had new engine 
>>>>>mounts installed, and the engine noise and vibration, especially at low 
>>>>>RPMs, went up tremendously.  I have always thought this was because the 
>>>>>new engine mounts were much stiffer than the originals.  Other 
>>>>>thoughts?
>>>>>Martin Raphael
>>>>>Rhapsody #108
>>>>>----- Original Message ----- From: "Kirk McCullough" 
>>>>><kirk.mccullough at telus.net>
>>>>>To: <C320-List at Catalina320.com>
>>>>>Sent: Wednesday, May 28, 2008 9:18 AM
>>>>>Subject: Re: [C320-list] New Engine Mounts
>>>>>
>>>>>
>>>>>>Mike
>>>>>>
>>>>>>Good advice, I'll add new mounts to the list. I have always put up 
>>>>>>with the "Perkins shudder" at low RPM, made even a little worse with 
>>>>>>the high pitched Kiwi prop when in reverse.
>>>>>>
>>>>>>Kirk
>>>>>>#124
>>>>>>----- Original Message ----- From: "Mike Shoffner" 
>>>>>><drshoffner at yahoo.com>
>>>>>>To: <c320-list at lists.catalina320.com>
>>>>>>Sent: Sunday, May 25, 2008 6:08 PM
>>>>>>Subject: [C320-list] New Engine Mounts
>>>>>>
>>>>>>
>>>>>>Over the years there have been threads devoted to the vibrations at 
>>>>>>low RPM's of the older boats with Perkins engines. I've noted this 
>>>>>>with my boat ever since I boughtit 4 years ago, and I've just 
>>>>>>attributed it to being a characteristic of the Perkins engine. 
>>>>>>Recently, because of my cutless bearing wearing out in one season of 
>>>>>>use, I had my shaft allignment checked and was advised I needed new 
>>>>>>engine mounts. What a difference!! The old "Perkins vibrations" 
>>>>>>apparently were due to worn engine mounts' and with new mounts there 
>>>>>>are zero vibrations at low RPM's. At higher RPM's engine noise and 
>>>>>>vibrations are also noticably reduced as well. Mine is a '94 model and 
>>>>>>probably needed new mounts for several years. I would advise owhners 
>>>>>>of more mature boats to consider having their engine mounts replaced 
>>>>>>if they're having problems similar to mine.
>>>>>>Regards,
>>>>>>Mike
>>>>>>#171
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>--
>>>>>>No virus found in this incoming message.
>>>>>>Checked by AVG.
>>>>>>Version: 7.5.524 / Virus Database: 269.24.1/1469 - Release Date: 
>>>>>>5/27/2008 1:25 PM
>>>>>>
>>>>>>
>>>>
>>>
>>> Pat Moriarty
>>> PSI Urethanes Inc
>>> PH: 800-888-5156  Fax: 512-837-8733
>>> Please visit our web site at
>>> www.psiurethanes.com
>>>
>>>
>>>
>>
> 