Featured Technical Broken Exhaust Flange Studs

BECAUSE I WILL PULL OUT 20 while your try'n to get the one... and I will never have to deal with the broke drill bit or ez out stuck in the stud..

 

you can weld the washer... or blow it out with a torch...

 

I have done these, but I prefer the drill, over the torch to “ blow out” the bolt. I have done the “ weld the nut” thing many, many times in my career!




Bones

 

Never try the “ easy out” if the stud twisted off! I have never been successful at that and quit using them many years ago in this case! I still have several sets of easy outs, but they rarely get used!




Bones

 

I really doubt that, but whatever you want to believe.

 

Some machine shops have machines that use an electrode that will disintegrate a broken stud . They are not real common any more, but they will remove the stud cleanly. If (as in your case) the stud was rusted in place before you broke it, you will likely need to retap the thread once you get the stud out. Many people try using an easy out. I have seldom ever had any luck using them with anything that's seized in place. Usually a lot of frustration is the only result. Then there is the method where you drill thru the stud. Normally its difficult to get the drill/hole centered and you make take some of the thread out while trying. You can however remove sufficient material that you may be able to weaken the broken stud. Then there is welding a nut to the broken stud and trying to remove it. That may work if there is still a little stud above the flat surface. The heat from the weld MAY help break the rusts bond on the stud.

If you take a cutting torch/welding torch and heat the flange around each stud until it turns bright red......do it a couple of times. That will pretty well always destroy the bond of rust between the stud and the manifold flange.

THEN..........after you have heated it with a real welding torch and gotten it red several times...........THEN try whatever method above appeals to you.

Personally I like welding a nut to the stud if there is enough stud in place to do it. If you don't use a real ox/acy torch for heat, most of the time it isn't hot enough.

Lastly, you can just drill it oversize and put a larger stud in it.

 

Yes, they are usually a waste of time from my experience. I like the "smoke wrench" option most of the time.

 

When i do have to drill a flush-broken bolt out, i always use reverse drill bits.... Progressively increasing the bit size. Sometimes you get lucky and twist what's left of it out as the walls get thinner and hotter.

 

Lots of mostly good info.
When it's broke flush or just a smidge down grab a flat washer and weld it hot to the bolt then weld a nut on top. I just hit opposite sides of the nut and grab it with vise grip

 

I find the heat and cool cycle needs to be done 5 time.

 

I tried the wax and welded nut method but iam not getting the penetration on the stud. Staying on it too long causes deformation and overflow on the nut which wont allow me to get a socket on.

 

big vise grips!

 

Heat it from the bottom side of the flange several times, using the wax method before you weld the nut on!

 

I did the wax and nut like mentioned. No luck. If i were to use a straight flute extractor is it best to have the stud ground flush to the flange or can it be up 1/4 inch or so?

 

it is BEST as everyone here agrees on... to not use an ex tool-if you are doing that much drill it hollow!

 

An "Easy-out", the world's most ironically named tool.

 

Lots of heat within a acetylene torch with a pinpoint tip.
Even then there is a chance you may break them off but getting them cherry red is probably the best approach to getting them loose and take them out well they are cherry red and use hand tools so you can feel it.

 

Does that actually work?
I mean I understand brass doesn't corrode at least not like steel but would that work for exhaust I mean I've never done it It's an honest question. I always thought brass was a little soft maybe but if somebody has first hand experience I will most definitely start using brass exhaust nuts. I think every one of us on this website that have ever taken off more than one or two exhaust manifolds have broke a stud and I think all of us have anxiety when we have to touch the exhaust bolts.

 

Brass nuts are on the french flatheads exhaust manifolds. They work and never seized in my 4 engines.

 

I always use brass nuts. Saved braking studs on my Harleys and now use them on all my motors when I get chance to swap them out. Seems to be traditional on vintage European and UK vehicles.

 

My '69 Corolla had brass exhaust manifold nuts. I've also found them on an early slant six, but they could have been swapped out. They don't fare too well after several decades of heating, and then being forced to run over rusty steel threads, but then they are consumable.

Back to heating exhaust studs to remove. The purpose of the heat is to break the bond between the threads of the stud and the female threads inside the casting.
Applying heat to the protruding part of the stud is not going to be as effective as heating the mass of the casting, since the object is to get the part of the stud that's inside the casting red hot.

 

When you heat something with a hole, the hole gets bigger. That's why the heating of the casting is more effective, it not only breaks the rust bond between the stud and casting, but also makes the threads in the casting larger diam. So the stud can be turned out. Welding/heating on the stud also helps break that rust bond, but making the hole larger is most effective vs making the stud larger.

X2 on using brass nuts when you put it back together after putting new studs in.

 

I've always had great luck with heating the casting around the stud and then quenching it with penetrating oil after it cools a bit. Spray it with penetrant until it stops smoking, and then spray it some more. I makes one hell of a smokey friggin' mess, but it hasn't failed to work yet.

 

I'll just add that heating/welding the on the stud can also anneal it making it softer. This condition is not helpful when trying to remove it.

 

Well, I’m going to have to throw my two cents worth in here! Like mentioned heat expands everything! So if you heat the stud, first, it will expand inside the cast iron housing. Hopefully breaking the rust bond between the stud and the cast iron. But you need to let it cool before trying to remove it, so it goes back down to its original size. Maybe only a few thousands of an inch. This is one approach.
The other is to heat the cast iron, expanding the hole, trying not to heat the stud, also in an attempt to break the rust bond. Of course after a bit the stud will heat up. Therefore you would want to try and turn the stud before it heats up….sometimes kinda hard to do.
Another approach is to heat the hell out of everything and hope!
I have used all three methods and many others …..sometimes with success…..sometimes not! It depends!
But a drill and a tap, as the last resort, will get it everytime, if done properly!




Bones

 

The coefficient of expansion of cast iron is 5.8 to 6.1, according to the Engineer's Toolbox site, whereas steel is 6.0 to 6.9. So as the casting is heated, the hole does grow, but the steel stud grows at a slightly faster rate. It's pretty much impossible to heat the casting around the stud without heating that stud at virtually the same rate.

The freeing action is due to the heat converting the complex iron oxide / hydroxide that is rust into different structures that take up less space, and losing water that is locked up in the rust molecules (which also reduces the volume).

 

Sorry Sleeper, but I have to disagree with you on cooling the cast iron more quickly after heating. Cast Iron is bad about cracking when cooled too fast. Not saying that people haven't done it and gotten away with it, but heating cast iron and cooling it quickly is taking an unnecessary chance (IMHO). I have an engine block right now that has a small crack where I Tig brazed a small pad to the side of it, about 1" diameter. Just self cooling caused it to crack. I think I can repair it, but from my experience, I'd caution anyone trying to artificially cool cast iron parts.

Again, IMHO.........Beanscoot is telling you the right stuff here. All I know is that I use a torch and most of the time it works.

 

You can disagree with me all you want, I was just saying what has ALWAYS worked for me. As both metals cool, the penetrant gets drawn into the threads and with little effort, the offending stud, bolt, nut or plug breaks loose and comes right out. Must just be dumb luck...
Try it some time and you'll see what I mean.

 

Heat with torch and push crayon onto thread where it screws into flange