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

Reply to
tedliu525
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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

Reply to
NapalmHeart

Reply to
user

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~

Reply to
B. Peg

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,

B. Peg wrote:

Reply to
tedliu525

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

Reply to
Private

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.

Reply to
SnoMan

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

Reply to
Private

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.

Reply to
madMike

If you're talking about the upper motor mount either you are looking at=20 the wrong spec or Haynes is way off. I have a spec here of 37 lb ft for=20 a 98'. No wonder it must have broke.

For installing studs refer to the following excerpt:

--------------------------------------------------- # Apply Loctite 242=AE or equivalent to 6-8 middle threads of clean front= =20 cover studs. # Apply Loctite 242=AE or equivalent to the threads of the holes in the=20 engine front cover using a cotton tipped applicator keeping the top 2=20 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.=20 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=B7m (18 lb ft). # Clean the excess threadlocker from the front cover and studs. # Install the engine mounts. Refer to

Reply to
blah blah

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

Reply to
blah blah

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

Reply to
blah blah

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