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550 / 456 Failed Motor Mounts - Pictures

Discussion in 'Technical Q&A' started by Doody, Apr 30, 2004.

  1. Doody

    Doody F1 Veteran

    Nov 16, 2001
    6,099
    MA USA
    Full Name:
    Mr. Doody
    as some of you may remember, i had a failed motor mount problem on my 550 last summer. others here have had this problem as well. i was cleaning up the garage this morning and wanted to post some pics so folks knew what to look for if they want to inspect their mounts. this was easily the most annoying, painful, and frustrating automotive mechanical problem i've ever encountered. so i saved the damn things as a "souvenir of my pain" :). yes, i'm less than normal - but you already knew that ;).

    grossly simplified, basically, the part is metal conical structure surrounded by another larger metal conical structure, with rubber in between. what happens is (at least in my case - i assume this is the standard fail pattern but i could be wrong!) that the interior metal cone separates from the rubber between the two metal structures, and eventually this lack of "support" for the engine can result in the engine, in various circumstances, touching or resting on the frame the rubber is intended to keep it off of. so you get all sorts of weird vibration transmisisons.

    the first picture is just a snap of the two mounts that were replaced in my car. they are about 11cm by 9cm by 5cm high. in the second picture you can see, around the interior metal circle, along roughly top and bottom ~120 degrees of arc how the rubber has split.

    these motor mounts are the topic of FNA TSB # 1041 "Engine Support Rubber Bushing" dated February 2003 (PDF attached). at that point they redesigned the part so it wasn't, well, ****ing stupid ;). you can see that the new part makes more engineering sense (at least to a non-MechE like me).

    fwiw, the anecdotal data on this board seems to suggest that cars driven very frequently develop the problem less often. in addition, the anecdotal data suggests that your authorized FNA dealer will replace them gratis if they fail. no guarantees on this! it's NOT the subject of a recall - but most folks here who have had problems have had them replaced gratis - whether it was automatic or it required some *****ing at FNA in NJ.

    hope this is helpful to someone someday!

    doody.
     
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  3. Doody

    Doody F1 Veteran

    Nov 16, 2001
    6,099
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    Mr. Doody
    here's another shopped version of that second picture. it wasn't entirely easy to see the failure arcs. i think it's clear here now. sorry 'bout that!

    doody.
     
  4. maranelloman

    maranelloman Guest

    Thanks, man. Been there, done that, as you'll recall. My case required some serioys *****ing...but, in the end, FNA came through. The fact that my warranty had expired only a couple of weeks prior undoubtedly helped....as did the persuasive skills of my dealer (Thanks, Phil!!)..
     
  5. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,400
    While the motor mount holds the engine it has to absorb both push and pull forces. ON one side push is acceleration and pull is deceleration (through engine compression), on the other side, the reverse.

    When the rubber separates, it can still provide the push function as the inner cone compresses the rubber the rubbber develops a force back. However, it has lost its ability to pull and the engine is "less than adequately supported" and can flop around in the engine bay -- maybe eveing hitting something you don't want hit.

    In addition, once the rubbber separates, it is exposed to oxygen and deteriorates at an accelerated pace.
     
  6. bobafett

    bobafett F1 Veteran

    Sep 28, 2002
    9,193
    Dave: curious, whom did you ***** @ exactly? I had a minor tussle with the local FNA Area Tech who did not want to help with an issue as I am not original owner, etc. Service guys were willing to help, though.

    --Dan
     
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  8. maranelloman

    maranelloman Guest


    I was put i touch with FNA's zone rep--forget his name--who was very professional, gracious, and helpful.
     
  9. Doody

    Doody F1 Veteran

    Nov 16, 2001
    6,099
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    Mr. Doody
    #7 Doody, May 31, 2006
    Last edited by a moderator: Sep 7, 2017
  10. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
    22,062
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    The Bad Guy
    Is there an updated mount? I would hate to think that a new one will just fail again.
     
  11. f355spider

    f355spider F1 World Champ
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    May 29, 2001
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    Hugh G. Rection
    Yup, read the first post.
     
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  13. ernie

    ernie Two Time F1 World Champ
    Lifetime Rossa Owner

    Nov 19, 2001
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    The Bad Guy
    Oh, Duuuuurr, LOL. :D I guess I should have read the first post, shouldn't I? I didn't even pay attention to it because I though he was just updating the pic. Anyway, thanks for pointing that out Dave.
     
  14. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    Phil Hughes
    FWIW, the same mounts are used on the transaxle too, but I havent seen a problem there yet.
     
  15. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,273
    Switzerland (NW)
    So what are the symptoms if the engine mounts fail ? Doody mentions vibrations in the transmission, but that's a bit vague ?
    I experience occasional vibes of the stick against the open gate in 3rd and 4th, would that be a sign that the engine is "sinking" into the front frame and therefore altering the position of the whole transaxle assembly ?
     
  16. ze_shark

    ze_shark Formula 3

    Jul 13, 2003
    1,273
    Switzerland (NW)
  17. Rifledriver

    Rifledriver Two Time F1 World Champ

    Apr 29, 2004
    27,086
    Austin TX
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    Brian Crall
    Some people feel and hear engine vibrations transmitted to the chassis and body of the car.

    That is of little importance. The mounts need to be visually checked, the oil pan to steering rack clearence is a good indicator. The reason I say the symptoms are of little importance is because the real problem is not the vibration that may or may not be felt. The real problem is that with bad motor mounts the oil pressure sender is very close to the antiswaybar and a flexing of the bar (has happened many, many times to 456+550 at the cost of total motor destruction) can break off the oil sender allowing a complete loss of oil in a couple of seconds.
     
  18. RacerX_GTO

    RacerX_GTO F1 World Champ
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    Nov 2, 2003
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    Gabe V.
    Would drivers see the needle drop on their oil instrument cluster as a result giving enough time to limp the car off the road before total seizure?
     
  19. ferrarifixer

    ferrarifixer F1 Veteran
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    Jul 22, 2003
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    As soon as the low oil pressure light comes on, switch off the engine and coast to a stop, and you'll be ok. The power steering will get heavy, so be prepared for extra effort there!... or, rather than live in fear of this nightmare...get your car serviced regularly and any good tech will spot it before it's too late.


    Symptoms.... as said, vibration through chassis on accel/decell. Also, just try the little finger test... you should be able to put your finger between the anti roll bar and the oil pressure sender... but you need the front floor off to try this.


    If you track your car, service/inspect it every ~10 track hours or so.
     
  20. damaged

    damaged Karting
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    Mar 1, 2006
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    D
     

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