[C320-list] New Engine Mounts

[Pat Moriarty]

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
>>>
>>>
>>>
>>>
>>>
>>>--
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>>>
>

Pat Moriarty
PSI Urethanes Inc
PH: 800-888-5156  Fax: 512-837-8733
Please visit our web site at
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