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Thread: Filling motor mounts

  1. #1
    Mitsu booster
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    Filling motor mounts

    Any thoughts on filling the gaps in the motor mounts with RTV instead of window sealant

  2. #2
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: Filling motor mounts

    Quote Originally Posted by pantera74l View Post
    Any thoughts on filling the gaps in the motor mounts with RTV instead of window sealant
    My thought: why would you want to?
    Buy the poly motor mounts and be done with it. It doesn't induce that much more vibration, but makes for a much firmer support with less rocking when engine is torqued.
    Wayne H.

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  3. #3
    Mitsu booster
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    Re: Filling motor mounts

    I've got an adjustable poly dogbone and can't find reasonably priced windshield sealant

  4. #4
    Hybrid booster
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    Re: Filling motor mounts

    just buy real urethane and pour it probobly enough to do 2 cars in a can http://www.energysuspensionparts.com/diymmi might as well use the right stuff the 3m window stuff is like 20$ or more a tube...

  5. #5
    boostaholic Turbo Mopar Contributor
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    Re: Filling motor mounts

    Quote Originally Posted by pantera74l View Post
    I've got an adjustable poly dogbone and can't find reasonably priced windshield sealant
    How cheap do you want it?

    http://www.autobodytoolmart.com/3m-a...3-p-15923.aspx

    This is where I buy mine from...

  6. #6

    Re: Filling motor mounts

    Filling mounts with high durometer polyurethane isnt anything to be frowned upon.

    My buddy did this to his trans mount, worked beautifully.

  7. #7
    Slugmobile & MeanMini Caretaker Turbo Mopar Contributor wheming's Avatar
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    Re: Filling motor mounts

    Quote Originally Posted by OmniPotentGLH View Post
    Filling mounts with high durometer polyurethane isnt anything to be frowned upon.

    My buddy did this to his trans mount, worked beautifully.
    Yes. Or you could use other stiff fillers, but the OP said RTV.
    I think a polybushings mount is superior to filling one with some unspecified rtv sealant.
    Its not that expensive and you don't have to worry about the filler coming out, and the factory rubber part still breaking down.
    Wayne H.

    '91 Dodge Spirit ES 2.5L turbo 5spd
    '05 PT GT 2.4T HO autostick (RIP)
    '89 Plymouth Acclaim 2.5L turbo auto, "Slugmobile" yes, THE Slugmobile!
    '89 Dodge Caravan SE 2.5L turbo auto, "Mean Mini" yes, Gus' Mean Mini! (Current best 11.699 @ 114.43 mph! - Oct 15th, 2022 Cecil County Dragway, MD)
    MeanMini dragracing videos: https://www.youtube.com/playlist?lis...URZLB1RxGYF6vw
    and other cars, trucks and motorcycles
    https://www.youtube.com/user/SlugmobileMeanMini

  8. #8
    boostaholic
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    Re: Filling motor mounts

    From my experience doing this, I would stick with a low duro # if you value NVH quality. If there is a commercial product out there with user feedback, you know what you're going to get in that dept... NVH would be my main concern.
    MinivanRider

  9. #9
    turbo addict
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    Re: Filling motor mounts

    Quote Originally Posted by Fox View Post
    just buy real urethane and pour it probobly enough to do 2 cars in a can http://www.energysuspensionparts.com/diymmi might as well use the right stuff the 3m window stuff is like 20$ or more a tube...
    I've used this in the 90A before, I bought it from mcmaster-carr and paid more for it. I've also used window weld. Both seemed to be about the same when it came to NVH. I wouldn't bother with RTV, I don't think it will really do anything other than make it look filled.

  10. #10
    Garrett booster
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    Re: Filling motor mounts

    i've used the flexane (80 & 94) both cracked out after a couple of years..
    now i use 3m window weld.. nothing else .. rock solid for 3 years.. just fill the cracks.. no need to do the sides of the mounts..
    make sure to rough up (i used wood rasp) and clean thoroughly -- takes a couple of days to dry..

  11. #11
    Supporting Member II Turbo Mopar Contributor A.J.'s Avatar
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    Re: Filling motor mounts

    I don't think RTV would be a good filler. It's suppose to be sandwiched between two parts.

    I like using the 3M windshield weld because it's thick and you don't have to tape anything off. It's also easy to dispense from a caulking gun. Depending how deep the cavity is, it usually takes about a week to dry. That's if I'm doing if for a customer, something non-turbo Dodge. Otherwise I'd rather give the business to Johnny at Polybushings.

  12. #12
    Supporting Member Turbo Mopar Contributor mopar-tech's Avatar
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    Re: Filling motor mounts

    Quote Originally Posted by pantera74l View Post
    Any thoughts on filling the gaps in the motor mounts with RTV instead of window sealant
    RTV pops out, been there and tried that.


    Working on clearing the decks.

  13. #13
    Moderator Turbo Mopar Staff Force Fed Mopar's Avatar
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    Re: Filling motor mounts

    Polyurethane does transmit a fair amount of vibration. Had a poly mount in the Lebaron, it was on the verge of being too much for a DD. Actually had that and a Polybushings bobble strut, ran that a year or so and finally decided I'd had enough. Installed a factory hyd bobble strut and it halved the vibration at idle pretty much.

    FTR it never had any real vibration issue while driving though. Only while idling. 2.5 w/ balance shafts removed.
    Rob M.
    '89 Turbo GTC

    2.5 TIII stroker, 568 w/ OBX and 3.77 FD

  14. #14
    Mitsu booster
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    Re: Filling motor mounts

    Thanks

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