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#1
Old 12-29-2017, 04:59 PM
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Removing rusted bolts from holes (exhaust work on car)

I am replacing the flex pipe and two mufflers on our 2005 Saab, i.e. everything downstream from the catalytic converter1. I used a Sawzall to cut the flange bolts where the flex pipe connects to the catalytic converter.

The two holes in the flange (for the catalytic converter) now contain the rusted remains of the two bolts. I tried pounding them out using a hammer and punch, but they won’t budge. What should I do? Drill them out? Grind them out? Somehow press them out? Would a torch help?

Pic 1
Pic 2
Pic 3

1In an unheated garage in central Ohio, I might add.
#2
Old 12-29-2017, 05:10 PM
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I guess you could attempt using a screw extractor but if it's rusted in that much drilling may be the only option. However, if you are in an unheated garage in Ohio right now I assume it's bitterly cold and maybe a torch will loosen them up. Are you right under the gas tank though? I know guys do this all the time, but lighting yourself on fire is not the best way to warm up in this weather.
#3
Old 12-29-2017, 05:21 PM
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I would try and drill them out and then use an extractor. Getting as perfect a center as possible on your drill. Start small. After drilling you may want to get a torch, plumber map gas torch would work and get it very hot and then soak in penetrating oil. I don't think an extractor would be strong enough if they are seized. If you put the extractor in and it still seems stuck use a small ball peen hammer to light rap on the side of the flange while you are applying pressure. This will often break them loose.
#4
Old 12-29-2017, 05:34 PM
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HoneyBadgerDC is right on. The only (minor) thing I would add is to make sure you use oil when you drill out the bolts. It doesn't have to be cutting oil...even oil from the dipstick will help immensely.
#5
Old 12-29-2017, 06:13 PM
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Thanks for the advice.

Just now I heated the flange with a torch and (again) tried to pound them out, but they wouldn't budge. They're completely rusted in the holes.

Now when you say "extractor," I do own this set of bolt extractors. Is that what you’re referring to?

Thanks
#6
Old 12-29-2017, 06:19 PM
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I think you are going to have a hell of a time drilling the pilot hole in the broken bolt from under the car, horizontally...
If you have one, use a center punch to create a dimple, and then use the smallest, sharpest drill bit you have to drill the first hole.
#7
Old 12-29-2017, 06:27 PM
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That's the set. I wouldn't bother though. Just drill out using increasing size drills. Threads will eventually peel out of the hole. Oil.
#8
Old 12-29-2017, 06:54 PM
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Quote:
Originally Posted by Crafter_Man View Post
Thanks for the advice.

Just now I heated the flange with a torch and (again) tried to pound them out, but they wouldn't budge. They're completely rusted in the holes.

Now when you say "extractor," I do own this set of bolt extractors. Is that what you’re referring to?

Thanks
what kind of torch did you use? cause mapp gas or propane isn't going to do the job. use an oxygen/ acetylene torch set-up with a size 0 to 2 tip & get it glowing cherry red. then use a punch with a pointed tip & a hammer.

you may have to do this more than once. air hammer with a pointed tip works real well too..
#9
Old 12-29-2017, 07:15 PM
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I'm kinda concerned about that first picture where it looks like i see a jack stand with air space between it & the car.

i nearly got killed when a car came off a jack (crushed my head between the car & the pavement. they had to sew my ear back on where I'd pulled it almost off from having to pry my head from under the car. the pinch weld of the body of the car was what was keeping it from coming out.)

anyway, just be careful.
#10
Old 12-29-2017, 07:17 PM
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MAPP gas based torches will work well enough. I'd recommend a combination of PB Blaster sprayed liberally on it and then torching and punching. They will give out eventually.
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#11
Old 12-29-2017, 07:18 PM
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Quote:
Originally Posted by mr horsepower View Post
what kind of torch did you use? cause mapp gas or propane isn't going to do the job. use an oxygen/ acetylene torch set-up with a size 0 to 2 tip & get it glowing cherry red. then use a punch with a pointed tip & a hammer.

you may have to do this more than once. air hammer with a pointed tip works real well too..
Just propane. And I don't have an air hammer.

I think I'll take smithsb's advice and try drilling them out using progressively larger bits, and see what happens.
#12
Old 12-29-2017, 07:21 PM
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Originally Posted by mr horsepower View Post
I'm kinda concerned about that first picture where it looks like i see a jack stand with air space between it & the car.
Perhaps this is not the best way of doing it, but the jack is holding it in the center, and I put safety jacks under the left and right structural members. There's about a 0.5 inch gap between the the top of each jack and the structural member.
#13
Old 12-29-2017, 07:39 PM
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Originally Posted by Crafter_Man View Post
Perhaps this is not the best way of doing it, but the jack is holding it in the center, and I put safety jacks under the left and right structural members. There's about a 0.5 inch gap between the the top of each jack and the structural member.
is there a reason you're not making use of the jack stands? it sounds like they're just being used for back up or something.
#14
Old 12-29-2017, 08:04 PM
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Originally Posted by FoieGrasIsEvil View Post
MAPP gas based torches will work well enough. I'd recommend a combination of PB Blaster sprayed liberally on it and then torching and punching. They will give out eventually.
I've got a screamer tip (good, hot $75 tip) for my mapp gas torch. i bet it'd take almost a full bottle of mapp gas to maybe work. I'd have those out in a minute start to finish with my oxygen/ acetylene torch.

i do understand though that not everyone has the shop or portable torch kits that i do, but it's possible he might know a plumber or hvac tech that does.

pb blaster is awesome shit. he'll want to spray that on the other side of that flange.

Last edited by mr horsepower; 12-29-2017 at 08:06 PM.
#15
Old 12-29-2017, 08:10 PM
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Do you have the bolt heads? If they're marked with radial lines they'll be made of very hard steel and difficult to drill. If you have to drill follow beowulff's advice and use a small high quality bit to start with. Try the screw extractors or punching them out every once in a while as the hole gets deeper. If those were the original bolts they may not be marked but they're likely to be made of some tough metal anyway.
#16
Old 12-29-2017, 08:14 PM
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Originally Posted by Crafter_Man View Post
Just propane. And I don't have an air hammer.

I think I'll take smithsb's advice and try drilling them out using progressively larger bits, and see what happens.
I'd exercise extreme caution doing this, not because it's dangerous, but because you want to preserve the threads for the new bolts.
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#17
Old 12-29-2017, 08:17 PM
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Quote:
Originally Posted by mr horsepower View Post
I've got a screamer tip (good, hot $75 tip) for my mapp gas torch. i bet it'd take almost a full bottle of mapp gas to maybe work. I'd have those out in a minute start to finish with my oxygen/ acetylene torch.

i do understand though that not everyone has the shop or portable torch kits that i do, but it's possible he might know a plumber or hvac tech that does.

pb blaster is awesome shit. he'll want to spray that on the other side of that flange.
I used to deal with rusted bolts all the time, not on a car but in a car wash setting, on the equipment that needed almost constant maintenance once it aged. Due to the massive amounts of water, we'd get extreme levels of rust on bolts that weren't stainless (and even then...sometimes, due to acid chemical exposure in car wash soaps).
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#18
Old 12-29-2017, 09:06 PM
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Quote:
Originally Posted by FoieGrasIsEvil View Post
I'd exercise extreme caution doing this, not because it's dangerous, but because you want to preserve the threads for the new bolts.
i don't see that as an issue. firstly it's probably the shank of the bolt that's still in there, so there would be no threads. secondly, it's not an application that's super sensitive to a given bolt diameter or design. (I'm not saying not to try & preserve what's there, just that it's not going to be a big deal if he has to go to plan B)
#19
Old 12-29-2017, 09:33 PM
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Quote:
Originally Posted by mr horsepower View Post
i don't see that as an issue. firstly it's probably the shank of the bolt that's still in there, so there would be no threads. secondly, it's not an application that's super sensitive to a given bolt diameter or design. (I'm not saying not to try & preserve what's there, just that it's not going to be a big deal if he has to go to plan B)
You might be right. I like the cut of your jib, soldier. Your username suggests car knowledge, especially about cars that I love, admire and lust after. What's your story?

PM me if you don't wish to respond here.
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#20
Old 12-29-2017, 10:23 PM
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Quote:
Originally Posted by mr horsepower View Post
i don't see that as an issue. firstly it's probably the shank of the bolt that's still in there, so there would be no threads. secondly, it's not an application that's super sensitive to a given bolt diameter or design. (I'm not saying not to try & preserve what's there, just that it's not going to be a big deal if he has to go to plan B)
This is correct, And I should have been more clear in the OP: there as no threads. Each hole in the flange is just a hole. And the remnants of the bolt (in each hole) is just the smooth part of the bolt. The flanges were originally bolted together using standard bolts and nuts.
#21
Old 12-29-2017, 11:08 PM
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If that is the case you want to heat the flange only and then try and tap it out. You can't get much shock torque when striking something like that because it is not solid enough, best to use a very small light hammer and medium sized punch.
#22
Old 12-29-2017, 11:11 PM
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Quote:
Originally Posted by Crafter_Man View Post
the remnants of the bolt (in each hole) is just the smooth part of the bolt.
Not having to preserve threads makes the job much easier.

Either drill the remains out, or heat the area (red hot if you can) and punch them out.
#23
Old 12-30-2017, 12:48 AM
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Quote:
Originally Posted by FoieGrasIsEvil View Post
You might be right. I like the cut of your jib, soldier. Your username suggests car knowledge, especially about cars that I love, admire and lust after. What's your story?

PM me if you don't wish to respond here.
I've just been around cars forever.

used to love working on them until i did it professionally for years. i don't do that anymore but i still work on my vehicles & the random friends car i get talked into doing.

now i work as a general contractor mostly doing skilled trade stuff on residential & light commercial properties with the occasional welding job & odd job customers ask of me in between.

my member name is what a former co-worker/ mechanic used to call me. it's the mascot for clay smith racing cams name. he's the woodpecker with a cigar in his mouth.

http://mr-horsepower.com/images/prod...etail/A710.jpg
#24
Old 12-30-2017, 05:00 AM
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Originally Posted by mr horsepower View Post
I've just been around cars forever.

used to love working on them until i did it professionally for years. i don't do that anymore but i still work on my vehicles & the random friends car i get talked into doing.

now i work as a general contractor mostly doing skilled trade stuff on residential & light commercial properties with the occasional welding job & odd job customers ask of me in between.

my member name is what a former co-worker/ mechanic used to call me. it's the mascot for clay smith racing cams name. he's the woodpecker with a cigar in his mouth.

http://mr-horsepower.com/images/prod...etail/A710.jpg
I remember that logo! Awesomeness. Every college in every state that has a red bird as it's emblem should put a cigar in it's mouth. Anyways, what's your current ride?

I have a Bugatti Veyron that I bought used for $10,000 and have put a second 16 cylinder engine into, along with another four turbos. So now I have eight turbos, thirty two cylinders and 22 radiators. It's pretty damn fast, actually.
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Last edited by FoieGrasIsEvil; 12-30-2017 at 05:00 AM.
#25
Old 12-30-2017, 05:01 AM
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Quote:
Originally Posted by FoieGrasIsEvil View Post
I remember that logo! Awesomeness. Every college in every state that has a red bird as it's emblem should put a cigar in it's mouth. Anyways, what's your current ride?

I have a Bugatti Veyron that I bought used for $10,000 and have put a second 16 cylinder engine into, along with another four turbos. So now I have eight turbos, thirty two cylinders and 22 radiators. It's pretty damn fast, actually.
Gas mileage remains an issue however.
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#26
Old 12-30-2017, 07:29 AM
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Quote:
Originally Posted by FoieGrasIsEvil View Post
I remember that logo! Awesomeness. Every college in every state that has a red bird as it's emblem should put a cigar in it's mouth. Anyways, what's your current ride?

I have a Bugatti Veyron that I bought used for $10,000 and have put a second 16 cylinder engine into, along with another four turbos. So now I have eight turbos, thirty two cylinders and 22 radiators. It's pretty damn fast, actually.
so you're the one who bought that one? i saw it listed on Craigslist too, i just didn't call the kid that owned it quick enough.
#27
Old 12-30-2017, 08:03 AM
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An aside: Check the top of your converter flange. From pic #3, it appears to have been leaking, and perhaps has cut the taper out of the flange.
May be time for a new converter too.
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#28
Old 12-30-2017, 08:34 AM
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People trying to get stuck bolts from marine diesel manifolds swear by PB Blaster. Might want to give it a try before working the extractor.
#29
Old 12-30-2017, 08:40 AM
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Originally Posted by txjim View Post
People trying to get stuck bolts from marine diesel manifolds swear by PB Blaster. Might want to give it a try before working the extractor.
Good stuff, I spent my entire life working on diesel trucks where frozen bolts were a part of my everyday life. It works, sometimes you have to wait on it a bit and re apply.
#30
Old 12-30-2017, 09:02 AM
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Originally Posted by txjim View Post
People trying to get stuck bolts from marine diesel manifolds swear by PB Blaster. Might want to give it a try before working the extractor.
Right.

I guess we really need to know, did you cut the bolt heads off with the sawzall? Or the end of a threaded bolt. 'cause it the bolt head is on the other side, an extractor is pointless.

Drilling may be your only option. And it sucks. Do you have a hi-speed dremel drill? That could be an option. A dremel drill would also help to put the pilot divit into the bolt to help center a regular drill. A very sharp punch can do this, but as that catalytic converter assembly is not rock solid, you may have a hard time with a hammer and punch to make any type of pilot 'dent' for a regular drill.
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Last edited by enipla; 12-30-2017 at 09:05 AM.
#31
Old 12-30-2017, 11:44 AM
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PB blaster is good, but take it from a machinist and mechanic with 45 years when I say do NOT USE EXTRACTORS OR "EASY OUTS". Sorry for yelling, but I've had way to many experiences with sad sacks who broke them off in stuff and had to come to the machine shop and have us worry the broken stuff out of the hole. They are made of extremely hard steel, work in very limited situations, and cause more problems than they solve. Do as others have advised, carefully center the punch mark, drill small holes through, and follow with larger drills. Step up at least 1/16" in diameter as you go and use cutting oil, not lubricating oil, if you can. If you're really lucky or good, you can drill the last part with the "tap drill" ( the size of drill intended for tapping the hole in the first place) and the old thread will peel out of the female threads. Good luck.
#32
Old 12-30-2017, 02:40 PM
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Thanks for all the expert advice.

Drilled both. Even when using lots of cutting oil I burned up four drill bits (and broke one). I then spent over an hour grinding out the holes using a Dremel. But finally... holes.

The next thing on the agenda is to warm up my fingers and toes so I can feel them again.
#33
Old 12-30-2017, 04:44 PM
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Quote:
Originally Posted by Crafter_Man View Post
Thanks for all the expert advice.

Drilled both. Even when using lots of cutting oil I burned up four drill bits (and broke one). I then spent over an hour grinding out the holes using a Dremel. But finally... holes.

The next thing on the agenda is to warm up my fingers and toes so I can feel them again.
Well done.
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