Motor Mount Problem

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.

Questions:

1) is it safe to drive the Saturn with only two studs holding the
engine
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

Ted

 

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
stud.

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.

Ken

 

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.

 

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~

 

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
mount.

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,

 

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

 

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.

 

snip

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

 

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.

 

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.
Notice

Refer to Fastener Notice in Cautions and Notices.

Notice

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

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

 

I hope I'm not behind anyone trying to save 2 cents worth of gas.

 

Should of been posted under this topic "Best time to shift?...."