[C320-list] New Engine Mounts

[Pat Moriarty]

You bring up a good question and I have not been down below to watch 
when it does the shake/knock but then I try not to let it happen 
either. Just put it in gear and give it a little throttle or leave 
the idle at 1000 rpm and no knock. Gori tried to tell me the new 
vibration with the prop is because the shaft is too long and I have 
lived with that till the boat gets pulled for the next bottom job, 
but I don't think that the .250" is going to make that much 
difference and I am sure that it will not change the over pitch of 
the prop. Love the prop but think the engineers are retarded. They 
think all boats are stripped and have a polished bottom for sizing a 
prop. In reality most have some bottom crud and fuel, water, waste, 
beer, etc on board so they weigh more than the factory spec and draw 
a little more depth.

Pat #130

At 09:25 AM 6/26/2008, you wrote:
>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
>>
>>
>

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