Motor Mount Problem

Discussion in 'General Motoring' started by tedliu525, Mar 20, 2006.

  1. tedliu525

    tedliu525 Guest

    I have a 94 SL2 auto transmission. Last summer, I replaced the upper
    motor mount with an aftermarket mount. I had to replace all three
    studs bacause the original studs were too short for the redigned mount.

    I got the new studs and the new nuts from a Saturn dealer. Thanks for
    so much helpful info on this newsgroup on replacing the upper mount. It

    was an easy job. After the replacement, my SL2 ran much smoother.

    Then recently I had noticed that the car ran very rough in the lower
    gears. Took a look at the car today and I found that one of the motor
    mount studs (the one that's closest to the front of the car, or the one

    which is furtherest away from the firewall) was broken inside the hold
    in the housing. And the middle nut was very loose. So I tightened the
    nuts on the two remaining studs. Unfortunately the broken stud was
    broken about 1/8 of an inche inside the stud hole housing.

    I test drove the car after I tightened the two nuts on the mount.
    And the car is now running very smooth in all gears.


    1) is it safe to drive the Saturn with only two studs holding the
    from the upper motor mount?

    2) how can I get the broken piece inside the hole out so that I could
    replace it? Can I use a small drill bit to drill the broken piece
    into small pieces and air blow? Does a machine shop do that kind
    of work?

    Thanks for any ponters

    tedliu525, Mar 20, 2006
  2. tedliu525

    NapalmHeart Guest

    I wouldn't for very long, especially since you aren't sure why the 1 broke.
    Here's what I would probably do.

    1.) Use an automatic centerpunch to put a punch mark in the center of the
    broken stud.

    2.) Use a small centerpunch to make the punch mark bigger. Take particular
    care to make sure the deepest part of the punch mark is dead centered on the

    3.) Get the appropriate size broken screw extractor (aka EZ-Out).

    4.) Drill a small pilot hole. 1/8" would probably be good. Be careful not
    to drill through the stud and into the surrounding metal.

    5.) Drill the hole to the size specified on the extractor. Again don't
    drill too far.

    6.) Put the extractor into the hole and lightly tap it with a hammer.

    7.) Carefully try to turn the stud out. I usually use a small adjustable
    (Crescent-type) wrench. Mine is a Proto brand.

    If you aren't comfortable with this, take it to a good mechanic. This
    procedure isn't fool proof. If the broken piece won't easily turn out, you
    could try heating the surrounding metal with a small propane torch. If that
    doesn't work, you could try drilling the piece out to a size just under the
    ID of the threads and collapsing the rest into the center of the hole. This
    can be a very tricky process for someone with no experience at it. If you
    get into the aluminum, you could easily cause expensive damage.

    Good luck.

    NapalmHeart, Mar 20, 2006
  3. tedliu525

    user Guest

    Is there enough metal left, if drilling & the easy-out route
    goes badly, to use helicoil thread inserts? Just curious as it
    would seem that it could be easy to strip the threads there and
    could be a bit of a problem.
    user, Mar 20, 2006
  4. tedliu525

    B. Peg Guest

    2) how can I get the broken piece inside the hole out so that I could
    If you have a reversible drill, go to Sears and get one of their Craftsman 7
    piece Drill-Out/Screw-Out Power Extractor sets (about 439 or so). The bit
    will allow you to remove the bolt by drilling in reverse so as to loosen the
    bolt (sometimes that alone will spin the bolt out) or use the reverse-screw
    at the end to screw the thing out once the pilot hole is in place. Works
    better than a generic fluted Easy-Out as their drill is harder and will
    drill almost anything without walking all over the place.

    B. Peg, Mar 20, 2006
  5. tedliu525

    tedliu525 Guest

    thanks all for your input. I have looked into all the suggesions.
    And I had also talked to a guy at a machine shop and showed
    him the broken stud. He told me that it was made of hardened
    material and it's difficult to just drill it, or to use bolt
    extractor to get it out, especially it is in an aluminum
    (not steel) engine. (And his shop does not do that kind of job).

    A guy from an auto shop told me his guys could do it. But he
    couldn't tell me how much it would cost because he did not
    know how long would it take. He guessed it might take one to
    two hours. Their rate was $94.00/hour.

    Then I went to talk to a service guy at a Saturn dealer.
    He told me that they (Saturn dealer service) don't do
    that kid of work. He told me that it's ok to drive the car
    with only two studs holding the engine on the upper motor

    I think the reason the stud broke off is that i did not
    apply enough torque to the studs. The service guy at
    saturn couldn't tell me the torque spec for the mount!!!
    I just checked my Hayes manual this morning. It says
    the torque for the upper mount should be 74 ft-pounds
    (if I recall correctly). Does any has a different number?

    Thanks again,
    tedliu525, Mar 21, 2006
  6. tedliu525

    Private Guest

    He told me that it was made of hardened
    I would be very surprised if this was a (very much) hardened stud. If it
    was, it probably would not have broken. You can do a hardness test with a
    file on one of the other studs. If you still have the other piece of the
    stud you can also try to drill it as a test and for practice. You will need
    a SHARP and good quality HSS (high speed steel) drill bit and a good sharp
    center punch. Use some oil when drilling.
    This is very possible.

    Very important question. How far below the surface of the aluminum on the
    motor is the stud broken? Is the break flat (usually normal) or is it
    broken at a large angle?

    If the stud is not broken too deeply below the surface then BY FAR the best
    and easiest way to remove it is to weld a nut onto the end of the broken
    stud. There are several tricks to accomplishing this task. The best
    technique is to FIRST weld a washer (with a hole the same size as the stud)
    onto the broken stud. Let it cool, then the second step is to weld a large
    nut onto the washer. Let it cool completely before attempting to remove the
    stud. The action of the weld will cause the stud to shrink as it cools. It
    is actually easier to do this when the stud is broken in aluminum than steel
    or cast iron as there is less chance of welding to the casting.

    Make sure the welder knows what he is doing, most good welders are
    experienced with this technique. Make sure that the ground cable is clamped
    close to the same piece of the engine as the broken stud, (I would use an
    adjacent motor mount stud.) I would also disconnect the main computer and
    the battery and make sure that any radio equipment is turned off.

    Many people here would submit that it is easier and safer to just buy a
    front cover from a scrap yard. If you decide that this is the safer (but
    more labor) route to go then at least attempt to remove the broken stud from
    the (removed) cover using this method. It also works very well after some
    clumsy mechanic has broken a (hardened) drill or a (really hardened) ez-out
    in the broken stud.

    If the stud is broken at an angle then sometimes a piece of pipe can be
    fitted and welded to the broken stud but this is only possible on larger
    studs and usually requires several attempts as it is hard to make a good
    weld (blind) inside the pipe.

    Good luck. CAUTION YMMV
    Private, Mar 21, 2006
  7. tedliu525

    SnoMan Guest

    I have no doubt that it is at least a grade 5 bolt or possibly harder.
    Use a Titanium Nitride or Carbide drill bit and you will be able to
    drill it out. I would not use a regular Hi Speed Steel bit. Cool an
    lube bit with oil from time to time when drilling it.
    SnoMan, Mar 22, 2006
  8. tedliu525

    Private Guest


    We are using the term 'hardened' without properly defining it. Most
    automotive grade bolts and studs are grade 5 which is harder than hardware
    bolts and most threaded rod which is grade 3 (at best). Grade 8 bolts and
    studs are harder than grade 5 but IMHO can still be drilled successfully
    with HSS drill bits but do require a little lubricant and will probably
    require resharpening more often. Grade 12 bolts are harder yet and are also
    much harder to drill.

    Quality tools are always better and will stay sharp longer but everything is
    a compromise and very hard (and expensive) drill bits (and ESPECIALLY taps
    (like those sold by Snap On)) are often also often VERY brittle and can be
    more easily broken. I actually prefer cheap taps for this reason,
    especially when used to chase existing threads or in harder to cut materials
    as they do not seem to break as easily. There is a range of quality in HSS
    drill bits, some are quite good and some less so. I really do not have
    extensive experience with Titanium Nitride or Carbide drill bits as I am a
    cheap kind of guy and have seldom needed these special bits. I have used
    carbide bits and they are much harder but they are so expensive I reserve
    their use for when nothing else will work. I seldom use the drill and
    ez-out method as I have had much better luck using a welder but as always
    'you have to make do with what you have.'

    Just my .02 YMMV
    Private, Mar 22, 2006
  9. tedliu525

    madMike Guest

    Remember if you have a stud from the same kit, there should be a mark
    stamped on the exposed end that may give you hardness info. It may be
    tick marks similar to bolts, or numerals if it is metric (different
    hardness scale) a basic Handbook should tell you. If the cited torque
    spec is 74 ft/lbs, at that diameter, I would normally say you are
    dealing with a grade five but since you are dealing with an aluminium
    block, Im not sure.
    Ive been hearning about an electronic arc process to remove broken
    fasteners, but the work involved to prep it, it's unlikely to be worth
    it. if you find some one with the equipment to try this , all
    precautions mentioned above in welding preps apply.
    I didnot catch which motor mount stud it was... but if it is
    accesssable, a roto-tool with some means of stabelizing , and the
    proper exotic alloy bit for the metal involved. might get you out of
    this one.
    good luck. I broke a motor mount on my SL1 doing some offroading one
    Saturday ... Paid to have a CV joint replaced because I was SURE that
    was it.
    madMike, Mar 24, 2006
  10. tedliu525

    blah blah Guest

    If you're talking about the upper motor mount either you are looking at
    the wrong spec or Haynes is way off. I have a spec here of 37 lb ft for
    a 98'. No wonder it must have broke.

    For installing studs refer to the following excerpt:
    # Apply Loctite 242® or equivalent to 6-8 middle threads of clean front
    cover studs.
    # Apply Loctite 242® or equivalent to the threads of the holes in the
    engine front cover using a cotton tipped applicator keeping the top 2
    threads clean.

    Refer to Fastener Notice in Cautions and Notices.


    Do not over apply threadlocker or allow to accumulate in bottom of hole.
    The front cover could be damaged when the stud is installed.
    # Install the studs into the front cover.

    Tighten the engine mount front cover studs to 25 N·m (18 lb ft).
    # Clean the excess threadlocker from the front cover and studs.
    # Install the engine mounts. Refer to
    blah blah, Mar 24, 2006
  11. tedliu525

    blah blah Guest

    I hope I'm not behind anyone trying to save 2 cents worth of gas.
    blah blah, Mar 24, 2006
  12. tedliu525

    blah blah Guest

    Should of been posted under this topic "Best time to shift?...."
    blah blah, Mar 24, 2006
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