I just noticed that I have a broken stud coming from the down pipe to catalytic convertor. It's probably has been like this for awhile now. The other 2 studs plus the bracket bolt are not moving either. I sprayed a bunch of penetrating oil and I will let sit over night.

What is the best way to remove these while still on the truck? I need to replace rusted out cat and 02 up-stream sensor and put 2 new gaskets on. Im probably leaking exhaust with the broken stud. It smells bad, but never threw a code.

Any feed back is greatly appreciated.

Thank you!

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If I need to drill these out, what size stainless nuts and bolts should I get to replace the studs? What size bit should I use to drill out? and what if I can't remove the bracket bolt? Should I drill that out too?


Any feedback is greatly appreciated! Thanks

Oh boy. I would probably heat those nuts all up a few times and remove the exhaust off. Then weld a nut onto the stud. Then remove the stud out of the head as and option 1

Is the header leaking exhaust right there now? If not, I leave it alone until you need to pull that off for a reason.

Then fix it..

What looks to me what happened is someone didn't heat up this nuts abs studs till their red then let them cool all the way back down before removing and snapped the stud off in the past.


Option 2 would be to drill it out but I would at least try option 1 first.


Believe it or not most of the time, those will come off and you can screw a new stud into it. Provide you take your time and work everything slowly..




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In the vehicle removal will be tricky. The two methods that work for me are either welding a nut to the stud and trying to remove what is left of the stud, or using a bolt extractor and a lot of heat. More heat than your typical butane/propane handheld bottle torch is capable of. It might be worth it to take it by an exhaust shop and see what they would charge. Sometimes it's best to pay for that kind of headache to be someone else's problem.

Mmmm…. That looks fun.

Drilling that sorta thing would be a cast iron bastard. You’ll definitely want some really good bits if you go that route.

I would certainly have a acetylene torch around with a rose bud, and plenty of water, fire extinguisher, and a helper in case things get away from you. I would remove the other nuts on the manifold after a couple of heat cycles with the acetylene torch. Then I would attempt to heat that stud, and use a stud extractor.

That all said, be prepared for the possibility you may have to remove that crossover manifold. Given the rust in the photo, that sort of repair isn’t exactly a straight forward situation. You’ll also want a back up plan in case things don’t work out, certainly don’t begin the project without a back up vehicle.

Good luck. Be patient. Be thoughtful in how you tackle it. I am fisting it will definitely lead to more angst.

ETA, another possibility would be to move away from the stud in that hole, punch clear through, and use a bolt and nut combination. There’s a very real chance that the threads for that stud aren’t going to be threads by the time you’re done.

I broke a stud in that same (well, CA emissions pipe is a bit different) location.







Three welded-on nuts later, we drilled it out and replaced it with a bolt and nut. You can see how little rust is on the rest of the studs and exhaust - sometimes it just happens with exhaust work.

-Charlie

I am surprised you guys couldn't get it.
Did you make the stud glow red a few times with cutting torches? Or just weld the nut on hoping that would work? You are right though that once in a while nothing will get it.

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Drill only as a last resort. Chances of you drilling in the center, and keeping it on center are not good.
Heat & welding a nut onto what is left should work.

If you must drill, you will have better luck if you start with a center drill, which makes it easier to start where you want it due to the geometry and rigidity, then move onto a small-ish drill to pilot through (~1/8"). Then go with whatever is close up to a maximum of the tap-drill size for those studs (M10?)

Thanks for all of the great feedback!
I managed to drill a small hole through the broken stud and that's about it, I could barely fit my drill in that area. I heated up with propane until orange , but could not move any other nuts. Im going to take it to a muffler shop to see if they can manage. Not worth driving myself crazy. If they break more of them off, should I just go with normal nut and bolt?

You need heat. More heat the propane. Acetylene is needed.

Needs to get hot. Not meltimg hot but hot. It's the heat and cooling that will break the bond on that stud.

A small hole is a good thing and will help.

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Embrace the suck……

Acetylene is definitely what’s needed. Get a rose bud tip to help control the heat better.

I’ll be doing mine in a couple of weeks. Waiting to get done with the next wheeling trip before I walk across that mine field. Lots of heat and lots of penetration lube. That’s all I got.

It's the only chance you have to get them.

There are reasons why there are not just bolts that go through the header with nuts there.

Those oem nuts are non reusable because they slightly bit into the stud. This is so they can not vibrate loose when the engine is running.

In the rust belt, almost all the mechanics around here will hot those nuts and studs a few times before even attempting to take the nuts off.

Granted they soak them with the penatrating oil many times between the soaking.

Also if you going to weld a nut on it. It's best to try to get a nut that let's the stud stick through if possible as that will let you drive some welding heat into the stud as well.


From experience. Trying to just weld a nut on a stud. Doesn't penatrate the stud much. So you really have to slow the wire speed way down to have any success in this.


I can see by Charle try this is why his didn't bond the stud to the nut. All it did was weld the nut shut.

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We gave up after 3 because we kept spinning off more of the stud with the welded nut and there wasn't enough left to weld onto. We didn't do any heat on the flange or stud otherwise though, which would have been a good idea. We are rust noobs out here in my area.

-Charlie

It happens, I just know it the only chance you have of getting them out. Its the heat and cooling that will break the rust bond.

You just have to watch you don't go too far or you will just melt the metal away. Bright red is what you after. I do agree you have to just know from experience. so best to practice on another stud until you get the heat right correct.


I have actually seen the real professionals actually blow the studs out if they go through casting before.. I am no where near that caliber. If i tried that I probably just melt the casting header too..LOL..

I had to do that on a 2nd gen years ago, forget exactly what I did but remember it sucked. You can get Dewalt swivels for a 1/4" hex at most home depots, add on a couple 6" extensions before and a quick/hex drill bit after and you should be able to hit it