What is the best way to remove a stuck/rusted exhaust bolt?

Question

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.

Answer 1

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.

Answer 2

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.

Answer 3

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