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Thread: Engine mounts

  1. #1
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    Default Engine mounts

    I'm planning on upgrading my engine mounts. My existing mounts are close to 40 years old. Does anyone have information on factors in choosing mounts? Thanks.

  2. #2
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    Default

    More information....

    Boat type, size
    Engine make, hp

    What are existing mounts?

    Mounts should match coupling flexibility.
    If no thrust bearing is used, mounts must be capable of transmitting trust loads.

    Sent from my SM-G935F using Tapatalk

  3. #3
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    Default Re: Engine mounts

    Info to follow...

  4. #4
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    Default Re: Engine mounts

    Hi Cushy floats has some guidance material:

    http://www.missionsupplyonline.com/p...yfloat_eng.pdf

    Mark

  5. #5
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    Default Re: Engine mounts

    Lot of brands out there..

  6. #6
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    Default Re: Engine mounts

    Quote Originally Posted by mariner2k View Post
    Lot of brands out there..
    Yup, but I didn't find any other suppliers that provide some data regarding selection. Most of the other marine ones I've seen give a mass, but not if this includes prop thrust and no resonance information with different durometers. If you know of others can you post links ?

    Thanks,
    Mark
    Last edited by Mark0; 04-15-2018 at 07:01 PM.

  7. #7
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    Default Re: Engine mounts

    The mfr should be able to tell you what's needed. My Yanmar has the factory mounts & they weren't terribly expensive: about $80 for the forward pair & $35 for the aft one, IIRC. Keeping 'em to what the mfr recommends made it simpler.

    Being 15 years old (even though only about 220 hours, some of which was battery charging/water heating), I replaced them this year just 'cause.
    "If it ain't broke, you're not trying." - Red Green

  8. #8
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    Default Re: Engine mounts

    Here's a few that I found. One has a reference pdf, another has a calculator.
    I haven't been to the boat yet to gather the info I need.

    https://www.henleyspropellers.com/Pr...ineMounts.aspx

    https://www.avproductsinc.com/marine...alculator.html

    https://www.asap-supplies.com/us/eng...-engine-mounts

  9. #9
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    Default Re: Engine mounts

    Boat is a 45' sketch
    Engine is an 80 hp Mercedes OM 314@ 2800 rpm.
    Engine is 800 lb with a 200 lb. Paragon reduction gear.
    The mounts are on the engine, not the gear.
    I cannot find any info on the existing mounts. They look like typical aluminum based compression mounts.
    One question is that I noticed, there are compression mounts and shear mounts. Anyone have any knowledge as to which is better?
    Last edited by mariner2k; 04-21-2018 at 06:37 AM.

  10. #10
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    How is the output shaft coupled to the prop shaft?

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  11. #11
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    Default Re: Engine mounts

    Drivesaver.
    Since I last posted I did some research. Dual flex recommended a size. But, are they optimal for vibration dampening? Does anyone have any input on the mounts they currently use?
    Last edited by mariner2k; 05-29-2018 at 09:13 PM.

  12. #12
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    Default Re: Engine mounts

    You need to contact Drivesaver to specify the hardness of the mounts. Theres no point in going for "optimal vibration dampening" if too softer mounts chew out the drivesaver.
    My guess is the drivsaver is quite stiff, about 65 shore D hardness. Youd be practically rigidly mounting the engine, Id find a similar engine (weight/rpm/vintage) in the Henleys link above and use the miunt suggested.
    It wouldn't hurt to give Henley/Isoflex a call.

  13. #13
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    Default Re: Engine mounts

    My understanding is also that mounts are normally sized with a drivesaver. The only time you can use a non thrust rated mount is if you have another ridged thrust bearing / flexible coupling. We've installed an aquadrive on our boat, and then just used the guidance material from the cushy floats.

  14. #14
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    Default Re: Engine mounts

    Thats right Mark0, say you had no room in the bilge and needed to keep the shaft angle low, the engine would drive via a drive shaft with universal or cv joints, thrust would need to be taken up by a dedicated thtust bearing.
    Same thing applies to a V drive instalation....engine mounts aren't subjected to thrust loads.
    Generally, engines directly coupled to the shaft via tranmission require mounts to take thrust loads. In these cases, the engine is either rigidly bolted the engine beds or a near rigid polymer mount.
    The installation of a device like the Drivesaver shouldn't have a huge impact on the mounts to be used, consider it icing on the cake for vibration and electrolysis control.

  15. #15
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    Default

    I know some will be thinking "but my nice little engine was supplied with nice squishy rubber mounts." I've installed some of these factory setups, I think it makes their engines look good and is an expectation of the market.
    A bit like the automotive industry specifying 30psi in tyres so their cars drive nicely at the expense of tyre wear and performance. Ask a tyre manufacturer and they'll recommend 36psi for the same tyre.

    Sent from my SM-G935F using Tapatalk

  16. #16
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    Default Re: Engine mounts

    I think probably all marine mounts are built this way now, but it's important that they are constructed so that even if the 'rubber' lets go they stay together mechanically. I have seen older sheered off mounts that didn't captivate the stud, but that was a while ago.Scary.

    That's mandated in cat 1 for example, so if the boat is inverted the engine can't go flying around.

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