Stud problems
 

Ok, using oxy/ace torch. I have this one stud that giving me hell. Should i heat in the same area described in the rebuild book or around the outside of the case? I ask because in the book it described using a propane torch, not sure if it makes a difference. Plus there's a hazy oil residue left in the case that i don't want to mistakenly light on fire or something.

Fast,

I used the propane torch as described in the book. It worked on all but one which had to be taken to a specialty shop. I did have a guy try to use an arc welder on the stud, to no avail. Oxy/ace gets very hot but I seem to remember others doing it.

Just completed this on my 2.2 project due in part to Groesbeck Hurricane's generacity in loaning me the proper tool. Caution, heat the stur up at the base until just about red, but wait for it to cool slightly or you will distort/bend the stud. Ask me how I know...

1fast,

Once you get the targeted area hot (I didn't heat anything up)and you still have problems, other than taking the case to the shop to drill it out, I used my angle grinder to square off the stud, then with the biggest adjustable wrench I could find I cranked with slow, steady pressure. You may have to have your kid (or whomever) keep the case and stand from moving. It was scary but finally, snap, crackle, squeal and pop, all of them came loose... Good Luck!

The thing is i didn't heat the area nearly as hot as you guys described. When heating the stud area, i only needed to heat on the average, about 4-5 seconds in order to get the stud to start coming out. I was actually more curious on heating inside the case bore area because that the only thing that i haven't tried yet.

Use an oxy torch carefully - you can melt the case, and/or light it on fire...

-Wayne

Just to throw this in, i wanted to test and see how well the aluminum case acted as a heat sink. So i heat a specific area on the block for about 10 sec, then counted to 3 mississippi and touched it. To my surprise it was barely warm already getting cold. I should be ok with the torch cause i'm only running 7 psi through it and i'm using a welding/heating tip, not a cutting tip.

Hmmmmmm, I've been mentalling mesaging the idea of grinding the stud into shape for a large adjustable wrench. Only thing that bugs me is the fact that the one stuck is a dilvar stud, and i'm not sure if it'll get brittle and crack if i were to grind it down. Anyone ever try welding a nut onto the stud before?

heat the case in the cylinder bore, next to the stud, not the stud. there's a ton of info on this if you search the archives. use oxy/acet for best results. the case is a big heat sink, so chances of doing any damage to it are slim. i never killed one in 30 years.

Right - the cases are indeed very, very, very big heat sinks. Especially the aluminum ones (the studs really only break in the aluminum ones, so you wouldn't normally use a torch on a mag case). You can place a propane torch on an AL case for about 15-20 minutes, and it will just about get hot then. You can't do much damage with the propane. The oxy torch, however, you can indeed get carried away with. Use your head - don't do anything stupid...

-Wayne

I'll give it another go tomarrow, thanks gentlemen.

I'm proud to say that after a 2 weeks of battling (and learning to use a torch) i've concored the studs! Turns out that heating from the case cylinder bore is the way to go for those really hard studs. Now that i have free time for a couple of weeks, i should see about how i'm going to get my roll bar in the car since my mig welder is satan :) .

To reitterate an earlier post of mine I would have suggested to heat the stud, not the case.

Why?? well because of all the previously noted concerns about damaging the case.

Propane will not do the job, it will not get the stud hot enough.

Heat the stud until it just turns red, Per Bob W above. The reason you cannot do this to the case is that is will not turn color and suddenly melt on you. Once the stud has turned red you can be assured that the loctite bonds that have been holding the stud in place are GONE, broken. The stud, after cooling a bit, will back out easily.

The case sucks so much heat out that heating just the stud is a pretty safe method. The stud gets red, the case is much much cooler and will not be damaged. If you heat the case at the base, it will certainly work, but you run the risk of overdoing it and having a meltdown.

Well, with a small flame and 7psi regulated on both tanks, the flame isn't as hot as you'd think. Or at least it's hot, but the btu output i'd imagine isn't quite as high. With low pressure and a wide tip, the flame's low and it's not quite as concentrated as a smaller one, or at least that's my impression of it. Let me say as well that an assistant to keep constant pressure on the stud, while heating, till it breaks is basically a must because without it's pretty tough to balance the torch and pull/push on the wrench.

Snowman, this is not the first time I have seen you make this suggestion but it is dead wrong.

If you only heat the stud and not the case you are only going to make the stud expand in the bore and tighten.

One of the secrets of stud removal is cooling the stud when the hole is at its maximum temperature to break any bonding between the two and to give you maximum clearance which will also reduce damage to the threads.

The stud is NOT held in by pressure from the case! It is held in by loctite, a glue. If you break the bond of the glue, the stud will not be held in, heat does this. A small ammount of heat will weaken the bond, but not break it, so much effort is still required, the right ammount of heat, DESTROYS the bond.

There is almost NO temperature difference between the stud and the case, no matter which one you heat up first. Heat will make the case expand a little more than the stud, due th the difference in coefficients of expansion, so something may be gained, but again due the the intimate contact between the case and stud there is NO practical temperature difference between them.

You may say it is dead wrong, but you are wrong in saying so. IT WORKS. IF you have tried this and the stud dosen't back out very easily, it is because you didn't get the stud hot enough to break the glues bond. Once this bond is broken the stud will almost fall out, ie not much more than finger tight, unless the threads have been buggered. I have done this repeatedly, I have seen this done repeatedly, I have been told that it works by a professor of automotive machine shop technology, who has been using this method and teaching it for over 30 years, I have seen this demonstrated a dozen times, without failure, I have done this myself untold times without failure, IT WORKS!

Bad theory there Snowman. What magical force do you think holds on fasteners that don't use locktite or similar chemicals?

Corrosion and metal bonding are the two of the most powerful forces that keep fasteners from coming apart like they should. All the heat in the world will not do much to change these problems unless you use the heat in a way that will break the bonded surfaces apart and provide additional clearance for the corroded surfaces to move by one another.

If you stood on your head and removed studs it does not mean that the two events are related to each other.

In addition to years spent working in an automotive machine shop and additional years spent working on cars and motorcycles I know what I am talking about here.

If that is not enough for you I also got a degree in aerospace engineering while turning wrenches so I can also back up a lot of real world experience with a thourough understanding of metalurgy and mechanics.

Before you are expected to design aircraft or automobiles they teach you quite a bit about fastener technolgy on your way to a BSAE. Fasteners make the world go around after all.

So what about the professor and his zillions of students( mostly mechanics who do real day to day work) who all tend to agree with him?

The heat does also a lot of good on metal corrosion, and breaking any bond it may have made. The reason it breaks this bond is the slight difference in coefficients of expansion of the metals.

Ask almost any mechanic. Add a bunch of heat from a torch and it will almost invaribly make the thing come apart, easily.

Have you bothered to concider that your professor may be mistaken? Just cause someone lands a job at the local community college does not mean that everything they believe is automatically correct.

Its unfortunate to think that this bogus information is being passed down to his students.

As both an engineer and a mechanic I have seen my fare share of bogus 'knowledge' being passed around since most people do not have the insight or training to seperate the wheat from the chaff.

As I already stated your method will only push surfaces together, not pull them apart. Its kind of hard to break a bond using compression instead of tension. While your theory about burning out locktite is correct and probably explains why you think your method works it will not do jack squat for corroded and bonded fasteners.

Thats the facts and you will probably refuse to believe me since I have seen this argument made in other threads to you before yet you still appear to believe your own experience instead of dozens of other people who know better.

Loctite breaks down at a certain temperature, that is, it ceases to exhist. Thats why the loctite goes away, not any mechanical forces. The method does work. Ask anyone who has tried it. If you have not, do so. I have and it DOES work. As to corroded fasteners, it also does seem to work, I would hazard a guess that it is because of the difference in expansion rates. Once the "bond" is broken, things just come apart, relatively easily.

As to expansion rates, and trasfer of heat, I have personally analyzed this, and after careful consideration know to almost a certainty that the temperature differance between the stud and case is almost zero, after a period of only 3 seconds. There is almost NO difference between methods of heating, the case or stud. The Key difference is that the stud changes color, the case does not.
If you heat the stud until it just turns red, and then STOP, you will have a 2 or 3 second safty margin for the case. This may not sound like a lot but it is enouth. Letting them cool for 3 seconds or more guarentees they are at the same or nearly the same temp. At that point the case may acutally be slightly larger, due to the larger coefficient of expansion and the stud just a little smaller. Relatively speaking. In any case the epoxy is gone and if it will come apart, it will.

While snowman's scientific explanation behind why this method may work is open to debate (and I do see one or two potential holes in the theory), I see no reason for everyone to doubt that it doesn't work. If he says it works, then it probably works, namely for the reasons he says (breaking down the Loctite). Common sense would say that the stud expands in the hole, but snowman is saying heat the stud, break the Loctite, and then let it cool down, and then remove it (at least I think that's what he's saying). There is more than one way to skin a cat - I think we all need to be a little more open minded here. Let's save the barbs for engines supported by 2x4s, and 2-pronged engine stands.

Heating the bond (whether you heat the stud or the case) will expand both the stud and the case, and break corrosive bonds that exist there. Cooling the case down again will cause everything to contract, but the bonds will be broken. Whether you heat the case or the stud - whatever works is whatever works.

-Wayne

I regularly use heat cycling to break loose rusty, frozen fasteners. Works like a charm.

while you guys are duking it out ,i'll just mention this.. as a steel worker most of my life( small and big) this has worked for me and I dont care much for all therum babble.. heat your stud up ,same time have the twist force on it. after about red hot for a couple of seconds it should let loose. in case that dose not happen be ready to quinch it with your favorit loose juice [wd40]or equal.
If you have ever solderd pipes togather you can kind of imagine whats going on there it just gets sucked in!!
repeat the operation for really stubern stuff.
ON bolts like the nasty flywheel heat the head( not propane)and be ready with the rattle wrench and they will fly off.
make sure the window is open cause it gets a bit cloudy in the quinch proces.

vacation's over, here we go again.

I'll just repeat myself that the besides burning out the locktite expanding the threaded hole while at the same time you contract the fastner in the hole is the best method to remove bolts that are being held in by more than thread locker.

Many of us have removed enough non corroded fastners that are using thread lock to know that even the best thread locker is not enough to keep nuts, studs and bolts from coming off without the use of extreme heat.

I will have to 2nd the quench method

quote:Originally posted by afterburn 549
after about red hot for a couple of seconds it should let loose. in case that dose not happen be ready to quinch it with your favorit loose juice [wd40]or equal.

I have seen this demonstrated ( not haveing tried it personally) and besides having the bolt come out the smoke is quite impressive. Never had a bolt that stubborn, the only reason I have not tried it. I do beleive that is works if done exactly as described.

Snowman or Wayne - I've seen at least a couple of people mention heating the stud by attaching an arc welder to it and cycling it on/off until hot (ground to case, electrode on stud).
- Any concerns over this method?
- Will the "red hot" temperature, regardless whether from torch or welder, embrittle the Dilivar studs?
Thanks
Rob

I've only removed around 70 case studs and each case I just heated the stud at the stud/case junction with MAPP gas torch to break the bond and they backed right out. These were 3.0, 3.2 and 3.6 aluminum cases.
-Chris

I guess everyone has an opinion on this. I have to say I agree with Snowman on most of this. I always use the heat the stud method and as I recall this is also the technique described in Bruce Andersons book. There is a good article on this very subject in the current issue of Grassroots Motorsports. While they don't get everything right in every article they recommend heating till dull red and then letting cool slightly berfore applying torque and I agree with the reasoning they present.

I'm sure both methods have merit but the heat the stud method is much easier and safer in my opinion.

-Andy

Dosen't sound safe to me because you may ruin the stud and if not hooked up properly, ie just to the stud, you might end up with a very permanent stud in the case.

Probably shouldn't reuse these studs anyway. If concerned do not heat as much, ie just to the point the joint smokes, which should mean the oil and/or locktite burned up, or if you are really really concerned, even paranoid, put a thermocouple on the case next to the bolt. Heat to about 500 deg F and start removing the bolt while hot. The heat will not destroy the bond but will soften it significantly. THis method may result in an even stronger bond if it cools,, so get it out while hot. Not to worry as you can always "Smoke it" if you have to.

One downside to heating the stud instead of the case is that with steel studs it can significantly harden the stud which increases the chance of fracture and makes it next to impossible to drill out if it ends up breaking close to the case.

I only had two really stubborn studs on my motor in the end, where heating at the juncture didn't work. For those two i heat with the oxy/ace torch inside where the barrel sits. I actually had to let it sit over night to fully cool, then heat only the inside of the case, not stud, to try and get the case threads to expand faster than the steel stud. And it worked, of course it was a once shot deal to keep the stud from heating with the case, so i had to have someone else put constant rotational pressure on the stud while i heated the case. With the arc welder though, i have no idea. I'd think that since a mapp gas torch is a fairly cheap buy at home depot, that you'd just use that. Btw, none of my dilivar's broke, i think that happens when they've already worn off there protective coating as started corroding, which in that case mine weren't bad at all.
Edit: I just realized that one of the stubborn ones was a dilivar stud, oops.

There is NO WAY the stud will heat at a differen't rate than the case where they are in intimate contact with one another! The logic that the case will expand more than the stud if one trys to heat just the case is totally false. If the case happens to expand more it would be due to the difference in the coefficient of expansion, NOT the temperature. Thats because the case and stud, where they are in solid contact with one another are at EXACTLY the same temperature, period.

THe whole reason for heating the studs is to burn up the locktite glue that bonds the parts togather. Once the glue is fried, it no longer holds and the stud comes out, that simple. THe heat is NOT to try and make the two metals expand at a differen't rate, cause it ain't possible, where they are in intimate contact with one another. Another thing the heat does, is on a very transient basis, cause the two metals to expand at slightly differen't rates, this difference can also help break any bond that may have formed due to rust or corrosion, but in terms of trying to make one part bigger than the other, no way.

Jack,
While I agree with your method of removing the case studs, I'll have to disagree with your assessment that the temperature of the stud and the adjacent case are at the same temperature.

If the stud is heated to a dark red to cherry red color to break the Loctite bond, that equates to a temperature range of 1200-1600ºF. Aluminum or magnesium alloys melt around 1220ºF. If the metal surrounding the stud is the same temperature as the red hot stud, the case would melt. However, it doesn't. That's because of the heat transfer characteristics of these non-ferrous metals and the heat sink property provided by the hunk of crankcase metal.

Interesting discussion. As Wayne mentions, there's more than one way to skin a cat. Readers now have a choice to try on their case studs. Thanks for looking at it from different angles.

BTW, rapidly cooling the stud (quenching) and/or slowing the cooldown rate (annealing) will change the molecular characteristics of the stud.

Sherwood

Yeah.... :rolleyes:

The reason the case dosen't melt is because the heat transfer down the length of the stud has a very high drop in temp. The case is a MASSIVE heat sink. The stud cannot supply enough heat, thru its length, to heat the case up to anywhere as hot as the stud is just a very very short distance above the case. If the stud were red, where it meets the case, the case would indeed melt. But once you get to the case, at every increment of length you go into the case you would find the stud and case to be at the same temp at the same depth. IF you heat just the case, the stud will be at the same temp as the case at every point along the stud. Any difference would be so small to be totally neglible and probably unmeasurable. YOu could probably calculate the difference, but then you would know why what I stated is true.

Hey snow, I am an engineer but I will give you a good real world example of why temperatures can vary greatly between adjacent metals.

Take a thick metal rod, hold one end with your hand and put the other in a hot torch flame. I guarantee you can melt one end before the heat can even start to flux to the end where your hand is located. Temperature variances can be great even across a solid block of metal, let alone different metals with material boundries.

To top off this debate I am currently working as a machinist again which involves a lot of broken bolt and stud removal. I also have to remove a lot of press fit gears. Do you think that involves heating the gear or the shaft?

You make one good point, this is why the case dosen't melt when the stud is red hot.

I know what you are saying BUT when a stud is stuck or a gear is stuck on its shaft, the part of the stud or gear that is stuck is very very close to the part it is stuck to, so close that it is STUCK togather. When parts are this close togather the areas that are stuck are so close to each other that there is NO real temp difference between them at those points.

Unfortunately the part in the center is usually so small relative to the part it is stuck in that the part in the center will be at the same temp as the surrounding part is. The speed that the heat is transferred is so fast that there is no time to accomplish anything during the transient phase.

I tried the stick-welder power source idea on broken exhaust studs. I could not get them hot enough. I think the head was too much of a heat sink. I have seen it work on cast blocks.

exhaust studs are another animal entirely. they rarely come out no matter what you do, other than by drilling.