Exhaust Bolts

[Nick1911]

Anyone want to share your tips for dealing with extremely rusted exhaust bolts?

I hate working on exhaust, seems like every time I do, I end up with a broken off bolt heads and stripped heads.  I have to wonder, how do exhaust shops do this kind of work?  Do those guys just by default take the cutting torch to old fasteners and then drill out the stud, or something else?  Just torch heat then beat with an impact?

I've tried various penetrating oils, candle wax, etc without much luck.  I've tried heating the fastener up red hot - tends to distort and destroy the threads if there's any stud present.  For those of you with a torch, what kind of settings do you use for this kind of work (Torch #, oxy and acetylene pressure?)

TIA

[RoadKingLarry]

If I want to save the stud I'll use a welding tip and try to concentrate the heat on the nut and then let it cool from red before I put the wrench to it.

If it just a hanger or clamp and it's rusted solid I'll just blast it off.

[Jim147]

I also use a welding tip. I try to heat just the nut up to red and then hit it with my WD40/MMO mix. Very flammable, be ready to put it out. I'll try this a couple of times. If the nut won't hold a socket, I try to get the air hammer after it if I can get into the spot.

Worst case I cut the nut with a cutoff wheel or the torch and then weld a nut on what is left of the stud and do the heat, cool and impact on that.

jim

[French G.]

The only time a fastener is worth fighting to save is when it is a stud screwed into a manifold, try not to break those off wrenching on the nut. Cut the nut off with a nut-breaker, cut-off wheel, chisel, something. Fasteners should be required to use anti-seize or loctite, 90% of them anti-seize. Re-install new hardware with appropriate anti-seize. The only penetrating oil that has a chance is Kroil or PB Blaster. Use light heat on the fastener, followed by oil. A couple of cycles of that will either set your car and garage on fire or free the fastener. Or possibly nothing, at which point cut it.

[Hawkmoon]

I have to wonder, how do exhaust shops do this kind of work?  Do those guys just by default take the cutting torch to old fasteners and then drill out the stud, or something else?  Just torch heat then beat with an impact?

Yes.

[Tallpine]

I have to wonder, how do exhaust shops do this kind of work?

Cut everything off and put on all brand new parts.

Saves time and makes them more money.

 

[Brad Johnson]

Don't heat up the bolt.  That swells it in the hole, making it tighter.  Heat up the head around it to expand the bolt hole out from the bolt.  The higher the heat the better.  A small torch with a little tip doesn't heat the head fast enough, allowing heat to migrate into the bolt and causing it to swell and negate the expansion of the head.

Brad

[BobR]

You can also try a home brew of 50/50 ATF and acetone. Put a little on the area, smack with a hammer a few times and repeat as necessary. We used to use 100% oil of wintergreen when I worked on planes, it seemed to work just fine and left a nice smell behind. 

bob

[zxcvbob]

You can also try a home brew of 50/50 ATF and acetone. Put a little on the area, smack with a hammer a few times and repeat as necessary. We used to use 100% oil of wintergreen when I worked on planes, it seemed to work just fine and left a nice smell behind. 

bob

Be careful with oil of wintergreen (and oil of birch bark, which is the same thing)  Fatal amounts can be absorbed thru the skin and I don't think there's an antidote.

[BobR]

Oil of Wintergreen, also known as methyl salicylate, is a precursor to aspirin so it should not be handled by people who are allergic to aspirin without some type of skin protection. Even then I would be leery of using it if I were allergic to aspirin. But it sure can loosen rusted nuts and bolts. Also, if not allergic it is not a bad idea to wear gloves while using it to limit the amount of skin absorbation.

I bet Ed's Red would make a great penetrating oil as it has ATF, acetone and other stuff in it that would seem to help loosen rusted parts.

bob

[Tuco]

Clean away the rust. Fit a 6 sided socket to the nut.  Do not use a 12 pt, as they will slip and spin.  
The six pt. offers a better application of force to the fastener (Physicists, have your say).  
If corrosion has eaten away the metal to the point that the proper size wrench no longer fits, modify the fastener with grinder/file/etc to fit the next smallest wrench.
You want a tight fit.  

Special Tools^tm are also available to grip these corroded fasteners.
http://www.lislecorp.com/divisions/products/?product=67&division=1&category=11

Attach a long 1/4" extension (up to 8 or 12" if you have room) and use a 3/8"-1/4" adapter as needed.
Step up to a 3/8" ratchet.
Utilize it like a hand operated impact wrench, bouncing torque with your wrist into the stuck fastener.

ALSO  if you've got room, like when accessing manifold bolts through a wheel well or downpipe bolts with the car on a hoist, you can use the aforementioned 8"x 1/4" extension on an impact wrench AND GO SLOW.
The 1/4" extension introduces flex into the system, softening the blow. The stuck fastener will be "pushed" rather than "smacked" reducing the opportunity for snapped studs.

Like French, I do a couple of rounds of pb blaster or Kroil (preferred) for a few days and heat/cool cycles.

Or just use a nut splitter.  
After laying on your back in the snow for two hours spinning rounded nuts with a hammer and punch you'll agree that this model
http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=8967&group_ID=1019&store=snapon-store&dir=catalog
is worth every penny.

Reassemble using new nuts and spray-on copper anti-seize.

[cassandra and sara's daddy]

battery powered dremel with cut off wheel has surprised me.  tomorrow morning i have a date with my exhaust so i hope it works again

[cassandra and sara's daddy]

Worked fine

[French G.]

Dremel tools are mostly hobby crap, right until you get to that little cut-off wheel. Those things have saved me a number of times.

[Tallpine]

I've got one of those air driven cut off tools. :)

[cassandra and sara's daddy]

Dremel tools are mostly hobby crap, right until you get to that little cut-off wheel. Those things have saved me a number of times.

you took the words outa my mouth  when i bought mine i even told the guy i was bringing it back   i used it to cut off a rounded nut on a u joint and fell in love

[mtnbkr]

you took the words outa my mouth  when i bought mine i even told the guy i was bringing it back   i used it to cut off a rounded nut on a u joint and fell in love

I've had mine for nearly 20 years.  I can't seem to kill it and find uses all over the place. 

Chris