why do exhaust bolts like to break?

[1abSi]

why is it that if they cool off enough so you don't burn yourself when working on the car, the exhaust bolts snap in half like a stick of butter?

[JasonS1]

Those bolts go through A LOT of heat cycles, and I believe that they're fairly long, and not all that big around.

Just my $.02.

- Jason

[ahhhonda]

I don't know if you're looking for a serious answer or just venting your frustrations about them breaking, but here's my thoughts on a serious answer. The bolts are subject to repeated extreme temperature changes, as well as corrosion due to water and exhaust and whatever exterior sources that your car is exposed to(salt?). Bolts that have corrosion alone are hard enough to get off without breaking, add to that all the heating up and cooling down so many times and you end up with a very difficult to remove, soft bolt. When I was younger I used to help my dad work on aluminum boats. When he needed to soften aluminum rivets, he would heat them up in an oven and then dump them into cold water. This would soften the metal. I'm guessing the exhaust would go through similar circumstances in it's daily work.

[chunky]

b/c, when they cool, the metal shrinks, meaning the nut grabs onto the stud super tight.

when you heat it up, it causes everything to expand, greatly reducing the effort required to remove the nut.

if you're having problems, get a torch and heat those bitches till they're red hot, they'll come off.

[31102si]

I find spraying the bolts down with wd-40 helps. that is what I have always done, no broken bolts yet. ;)