My exhaust came apart where the exhaust pipe bolts to the back end of my catalytic converter. The studs are severely corroded where I could only use a die on one stud. One nut is currently holding it together.

My plan is to unplug the two O2 sensors, unbolt the down-pipe at the exhaust manifold, and pull out the catalytic converter/down-pipe as one unit.

A CC is expensive, so I would like to replace just the studs. I can buy replacement studs from Acura/Honda. Or use a high grade bolt as a temporary fix.

Has anyone removed/replaced these studs and have any advice?

I was thinking I would cut off the top of the stud and/or grind it down with my dremel. I am assuming it is spot welded on there. Then use a hammer/punch to knock out the stud from the thread side? I can pick up a c-clamp/press as well to push out the stud? Heat is another option and always wanted to get an acetylene torch.

Thanks in advance.

 

I've done that a couple times on different cars.

95 Integra
Just pounded out the studs, they weren't welded or anything. Lots of corrosion, I used penetrant, & was careful not to hammer hard enough to crack the ceramic monolith inside. For that car I bought studs from the dealer.

89 Saab
Again, just pounded out the studs. This one I bought stainless nuts & bolts from a well-equipped local hardware store. They didn't last as long as the dealer studs, but for the price I could replace them more often.

 

Wondering if galvanized bolts/nuts would be better.

 

I was able to disconnect both O2 sensors. Unbolt the down-pipe at the exhaust manifold (sheared the spring bolt holding the pipe to the manifold, removed exhaust manifold to get that out, what a PIA). Then unbolted at the back of the converter.

The studs are not spot welded on there, or the salt on the roads up north took care of them.

I just used a 32oz ball-peen hammer from harbor freight. It took 5-10 good hits on the stud to knock it loose. If I hadn't broken off the spring bolt, this would have been a breeze. Nothing is ever easy when doing DIY work.

Thanks for the advice. I have 5.5 grade bolts in there right now. I'll order the studs from Acura at some point and fix it the proper way.

 

I'm also having to remove my rusted studs(rusted so much I can't tell where the nut is). Does anyone know approximately what diameter the stud is? Looks to be around 5/16''.

@Jimblake: How did the stainless bolts fail?

I found a picture of the studs here (BOLT, CONVERTER (18176-P08-003) - $9.41 - 18176P08003) Aside from the specialized splines that create the interference fit, I'm not really sure why the bolts are so much. They appear to be alloy steel, and if they are, offer little corrosion resistance. I was looking at exhaust and noticed NAPA sells flange nuts with copper plating? Rust-proof?

 

Not sure I remember exactly how they failed. Probably more accurate to say the stainless bolts didn't really fail by themselves. I had to replace the exhaust pipes for other leaks, and the bolts had stretched a bit and frankly a new set of nuts & bolts was just so inexpensive that I replaced them.

The "specialized splines" aren't really too profound. I recall they grip the holes in the converter flange and simply prevent the bolts from spinning when you tighten the nuts. Pretty much like the lug bolts that are pressed into the wheel hubs.