Good evening HT, I have an issue that i need some light on.

First let me give you the details, 2000 Honda civic ex (auto) with a stock exhaust setup.

Recently my exhaust pipe broke from behind the resonator and it was broken for about 2.5 weeks ( i was away for work if you must know) i took it to a local muffler shop to have them cut, bend and weld that damaged pipe from the resonator to the muffler. Everything worked fine, the car was quiet no rattles or anything out of the ordinary until i hit the highway later that day. I heard a loud terrible sound that vibrated the entire car which indicated that my exhaust either broke again or something came loose.when i got home i went under the car and shook the exhaust to see that the 3 bolts holding the cat to the resonator broke free. upon further inspection the next day i saw that those 3 bolts were welded rather than tightened with a self locking nut which made a simple diy turn into a shop job. my question is, was there too much pressure in my exhaust to break those 3 welds free or was it because it was old and rusted it broke free? replacing the cat is not a problem because clearly those 3 bolts are welded onto the cat and can not be removed from what i know but i want to be certain that nothing else will pop off like that if i do replace the cat. I have attached an image below with a red circle indicating the separation point. The car is bone stock, no engine or tuning mods and no check engine light came on. thanks.

 

can you post a pic? and im assuming its a stock exhaust system right? I assume they broke off well loose due to rust, especially if you were going on the freeway where there was more exhaust pressure.

 

Those bolts aren't welded on from the factory, they're a flanged head - that way, you only need one wrench to undo the nut, and the bolt won't rotate. Either your exhaust is rusted to hell, or someone did some fucked up repair job in the past.

No, exhaust "pressure" won't snap welds. Your motor will die before welds break.

 

you might have scraped on some crappy driveway. or bottomed out somewhere
check for bumps and deep scratches

 

I'd have to get under the car to post a pic, ill see what i can do. i'm leaning more towards the rusted side myself as that part of the exhaust has never been touched by me.

Thanks for clearing that up, i knew something looked odd when i saw that there was no nut at the end on the resonator side, it's just chunks of welds to hold the bolts in place, i didn't even see a gasket when i took out the cat so the previous owner must of did a **** job because i never had reason to touch that part of the car until there was a problem.

The car sits pretty high, it's stock height but i guess when the pipe was broken for the 2 weeks it must of put some strain on the system and have the exhaust hang lower than normal but it was parked up for the time being while i was away.

Thank you all for the help!