Catalytic Converter...

[OR VietVet]

You may have to take a 14mm 6 sided socket and pound it on the nut. If I was you I would use an air or electric impact and you can "burp" it a little as you tighten and then reverse it and "burp" it a bit at a time to break it loose. You will have to push ******* to that nut since it is getting rounded.

 

[mijohnst]

Thank you, Ron. It's raining here all day so I guess it'll have to wait until Thursday when it stops. Great ideas!

 

[George B]

for reference 9/16 is 14.27 mm if you want to drive a socket larger than 14 mm on it.

 

[mijohnst]

for reference 9/16 is 14.27 mm if you want to drive a socket larger than 14 mm on it.

Good point. I'm going to try out that nut extractor that I ordered on Amazon and hope that does it. If it doesn't, my next option is a 9/16 socket. Thanks for the info!

 

[OR VietVet]

It would be best to use an impact 6 point socket. They don't flex and give as much and if you "burp" it with an impact it will rattle the nut and threads better when loosening.

 

[rockola1971]

I would have hit them with a grinder already and installed new bolt/nuts. Time is short and bolts/nuts are cheap.

 

[Wylie_Tahoe]

I removed the exhaust on mine (300K mls) just last nov. Those nuts didnt budge first go. Soaked my nuts for a few days with PB, then hit with heat as I cranked each one. They all popped loose and threaded right off.

I prefer to use a pull bar over impact here. I want to feel whats going on with the nut. If the socket start to round, I can feel and stop. You can even feel the stud twisting.

Coat with anit-seize when reinstalling.

 

[JonnyTahoe]

I would have hit them with a grinder already and installed new bolt/nuts. Time is short and bolts/nuts are cheap.

Big time frustration. Had a situation like this with a mid pipe connection flange bolt. Took it to a local muffler shop and had them get it off.

 

[mijohnst]

I removed the exhaust on mine (300K mls) just last nov. Those nuts didnt budge first go. Soaked my nuts for a few days with PB, then hit with heat as I cranked each one. They all popped loose and threaded right off.

I prefer to use a pull bar over impact here. I want to feel whats going on with the nut. If the socket start to round, I can feel and stop. You can even feel the stud twisting.

Coat with anit-seize when reinstalling.

Well, tonight is the night. I've been soaking each one with the penetrating oil Ron recommended twice a day for the past week. I bought that small oxy-acetylene kit that George recommended to heat those bolts up. One at a time I got them all cherry red and then cooled them off quickly with a spray bottle. Then they turned right off! Thank God I don't have to worry about broken studs to drill out. Thank you all for the help again!

I'm going to clean those stud threads up with my rethreader before I put the new one on. Thanks for reminding me about the anti-seise John. Hopefully, I'll never have to do this again. Does anyone have the torque spec I need to put the exhaust manifold back to the pipe flange? I read somewhere 35lb but that doesn't sound right.

I also want to add to anyone doing this with a 4x4... taking out my front drive shave gave me a lot more room to work with on the left side. Might as well change out those factory u-joins while it's up anyway.

 

[George B]

Well, tonight is the night. I've been soaking each one with the penetrating oil Ron recommended twice a day for the past week. I bought that small oxy-acetylene kit that George recommended to heat those bolts up. One at a time I got them all cherry red and then cooled them off quickly with a spray bottle. Then they turned right off! Thank God I don't have to worry about broken studs to drill out. Thank you all for the help again!

I'm going to clean those stud threads up with my rethreader before I put the new one on. Thanks for reminding me about the anti-seise John. Hopefully, I'll never have to do this again. Does anyone have the torque spec I need to put the exhaust manifold back to the pipe flange? I read somewhere 35lb but that doesn't sound right.

I also want to add to anyone doing this with a 4x4... taking out my front drive shave gave me a lot more room to work with on the left side. Might as well change out those factory u-joins while it's up anyway.

This is good news! I would recommend you buy some new high quality nuts and use one of them to chase the threads rather than something that will remove material. Use lots of oil! With anti-seize it will be hard to get a good torque reading so I wouldn’t go too tight. 35 is probably ok on that. You can always snug em again after a few heat cycles.