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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
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Old 08-13-2003, 03:10 AM
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I regularly use heat cycling to break loose rusty, frozen fasteners. Works like a charm.
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Old 08-13-2003, 06:15 AM
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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.
Old 08-14-2003, 07:38 AM
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Old 08-14-2003, 08:31 AM
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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.
Quote:
Originally posted by 350HP930
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.
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.
Old 08-14-2003, 03:20 PM
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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.
Old 08-14-2003, 05:27 PM
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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
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Old 10-20-2004, 09:35 AM
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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
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Old 10-20-2004, 10:26 AM
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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
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Old 10-20-2004, 10:53 AM
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Quote:
Originally posted by reedr11
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
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.
Old 10-20-2004, 02:17 PM
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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.
Old 10-20-2004, 02:56 PM
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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.
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Last edited by 1fastredsc; 10-20-2004 at 03:35 PM..
Old 10-20-2004, 03:31 PM
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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.
Old 10-20-2004, 09:31 PM
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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 1200-1600F. Aluminum or magnesium alloys melt around 1220F. 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

Last edited by 911pcars; 10-21-2004 at 02:22 AM..
Old 10-21-2004, 02:11 AM
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Old 10-21-2004, 06:06 PM
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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.

Last edited by snowman; 10-21-2004 at 07:58 PM..
Old 10-21-2004, 07:50 PM
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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?
Old 10-21-2004, 10:05 PM
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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.
Old 10-24-2004, 07:01 PM
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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.
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Old 10-25-2004, 06:30 AM
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exhaust studs are another animal entirely. they rarely come out no matter what you do, other than by drilling.
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Old 10-25-2004, 08:44 AM
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