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I'm trying to disassemble the exhaust system on a 2000-2003 nissan maxima and I'm having trouble removing one last bolt.. its got a 14mm head and its just plain STUCK. I've tried soaking it overnight with PB Blaster.. then the next morning i tried removing it with a 2ft long breaker bar + a 2ft extension. After making absolutely positive i was trying to turn it the proper direction, I braced my self by putting both feet on a framerail and pushing with all my strength... and then my socket shattered into a billion pieces. Bolt: 1 Me:0.

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The socket died before the 14mm bolt head broke off? You should really buy better tools :) – jensgram Mar 15 '11 at 9:05
I had made the mistake of using a Craftsman thin wall socket (i was under the car and didn't feel like crawling back out). To be fair, they did send me a new one. – NoCarrier Mar 15 '11 at 16:39
up vote 23 down vote accepted

My general rule for exhaust bolts/nuts is to order new ones with the part you are replacing, knowing full well that there is a good chance you'll destroy the ones you are removing. Better to be prepared ahead of time than to be stuck waiting for new parts from another country after you've disassembled everything. Personally, I have a rule of ordering every bolt and nut that is attached to the exhaust member I'll be replacing. Even if there isn't much rust, I never know when a bolt will snap.

First task is to let the exhaust completely cool. It's possible that the parts are made of different types of metal which expand and contract at different rates.

Now, how to get the rusted bolts off:

  • Use an impact wrench. Sometimes the vibration and hammering action works better to "knock" a bolt loose, compared to wrench/breaker bar. In my experience, this is the first tool of choice for 95% of techs working on an exhaust system.
  • Use a big breaker bar. 2 ft is okay, 4 ft is more like it. Use high quality, name brand tools that won't flex or shatter on you (or at least give you free replacements when they do shatter). The flexing is important. If the cheap breaker bar is flexing instead of transferring the full torque, you may as well not have it.

Sometimes there is just too much material rusted off of the bolt for either of the above to work. Or one of the above techniques may round out the bolt before it comes out. In this case, the bolt needs to be destroyed so you can move on with life. Some options are:

  • Die grinder with appropriate wheel.
  • Hacksaw / airsaw.
  • Air hammer with chisel bit.
  • In extreme cases, torch.

As always, use high temperature anti-seize when putting in the new bolts. They will go in easier, and the next person down the road will thank you.

Safety Note: All of the above methods assume you know the safety procedures for the tool. Of particular importance is having the vehicle properly raised on the car lift. Some of these methods involve violently pulling stuff around, which will cause the car to move.

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+1 for impact tools. I like the planning for bolt replacement also, so you are not stuck waiting on a part while your vehicle remains in pieces. – Troggy Mar 15 '11 at 6:44
Impact wrench is always the first thing I pull out for a stuck bolt. I've sheared a few off using a breaker bar, which always ruins my day... – Kendrick Mar 15 '11 at 14:06
+1 for impact tools too. They provide incredible torque + the shocks are priceless. You can have some that run on battery (Facom). Regarding the remounting you can also put "Copper grease". – Skippy Fastol Jul 5 '14 at 8:26
S_Niles, you forgot a "nutcracker". – TDHofstetter Aug 16 '14 at 17:41
@S_Niles I need to add a cordless impact wrench to do exhaust work. Which one should I get a 1/2 inch or a 3/8? Are there adapter sockets to go from 1/2 to 3/8 just like for regular tools? – Viriato Mar 19 '15 at 17:23

I find heat is far more effective at removing stubborn bolts than PB blaster or the like.

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If it's in a really tight spot dremels can work wonders too. I can't begin to tell you how many times I've had a bloody exhaust bolt seize on me.

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This is how I got my old manifold off. After trying everything I could, I busted out the dremel and cut the thing off. – Annath Mar 20 '11 at 14:45

Soaking in WD-40 or equivalent will help, but the real final measure is first a blowtorch - even a cheap and not-very-powerful one will do - followed by impact wrench.

Alternatively, you can buy hydraulic tools but they will probably snap the bolt leaving you with one more problem to solve.

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Doubt if my two cents is asked for but rust is oxidization. It's just burning reall slow. Torch with a brazing or welding tip is best. The rust disdappears like majic when you burn it the rest of the way up. I find no need for red hottin' it. Cast iron is brittle. Get a 650 degree heat stick and warm things evenly and cool slow coveted all up in vermiculite. Manifolds crack, then we do. be gentle

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You realize vermiculite is laced with asbestos, right? Works great for heat retention and insulation, but is really, really bad for the lungs (asbestosis/mesothelioma ... CANCER). It's actually better to bring it up to red hot, then cool it quickly with beeswax to get into the threads. This will loosen it up quicker and more safely than anything. – ᴘᴀᴜʟsᴛᴇʀ2 Jul 5 '14 at 13:54

An old steam fitters trick. Heat and candle wax. Heat the bolt and push a candle against the bolt an threads. If you got the bolt hot enough it will draw the wax into the thread.

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I own heavy equipment business sometimes works to start machine for a minute or two to heat up head slightly. Turn machine off then quickly attempt to remove bolt before heat transfers to it.

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Acetone and vegetable oil (search it) superior to any store-bought oil of the same purpose (yes even kroil.) As shown in lab experiment, drexel university.

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Do you have a link or anything not subjective which may show exactly what you are talking about (like the outcome of the tests and a brief description why it's better)? – ᴘᴀᴜʟsᴛᴇʀ2 Jun 21 '15 at 0:42

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