Resonator removal / replacement

[openwater04]

Heya!

I need to replace the resonator pipe in my 06 hatchy and the flange / flange nuts (or studs?) connecting it to the forward pipe is reallllly rusty. I can't even tell if they are bolts or studs... can anyone advise on that? I imagine I'm going to have to cut something off to replace this component, so I didn't want to grind anything away that was obviously needed to put the new Walker resonator on...

Thanks in advance!!

[avguy]

I did the same type of thing when the connector pipe on my muffler rusted out. I can tell you for certain that working with these rusted parts is a RPITA nightmare, if you plan to reattach with bolts. You would need to carefully cut/separate the flanges apart with a dremel or angle grinder, and then drill new holes for bolts. I strongly recommend you either weld the pieces, or else replace the entire exhaust system, right up to the cat, assuming that's also not a solid piece of rust.

[steelerdude99]

I had to do this job about a year ago. My orig. problem was rusted down-pipe (the one with the flex under the engine). Not one single joint could be separated. I had to cut the old stuff out as the AVEO welds bolts on their pipes. Even if you cut or break the bolt, you still have the "stump" to deal with via drill.

[openwater04]

I did the same type of thing when the connector pipe on my muffler rusted out. I can tell you for certain that working with these rusted parts is a RPITA nightmare, if you plan to reattach with bolts. You would need to carefully cut/separate the flanges apart with a dremel or angle grinder, and then drill new holes for bolts. I strongly recommend you either weld the pieces, or else replace the entire exhaust system, right up to the cat, assuming that's also not a solid piece of rust.

Replacing entire exhaust is probably what I'll attempt... I was planning on just the muff/resonator but I'll check the connection at the cat... hopefully those bolts are decent... thanks for the guidance!

Best
Nicholas

[steelerdude99]

Replacing entire exhaust is probably what I'll attempt... I was planning on just the muff/resonator but I'll check the connection at the cat... hopefully those bolts are decent... thanks for the guidance!

Best
Nicholas

The bottom nuts on the studs on my cat were a pain. They were just rounded and rusted nubs. I took the cat off at the header. I cut the sheet-metal heat shield so I did not have to remove the upper O2 sensor and out with a couple of bolts. As my goal replacing the rusted down-pipe; I did not care if I ruined the down-pipe. I expected to get the bottom cat bolts out on the bench. ... No such luck. Broke one off. Ended replacing the cat. The studs look like they were installed in the flange before the cat was welded together. It was like it was designed to assemble easy at the factory; the possible repair/replacement was not even a consideration. (maybe a consideration; they wanted it as difficult as possible ).

chuck

[avguy]

The bottom nuts on the studs on my cat were a pain. They were just rounded and rusted nubs. I took the cat off at the header. I cut the sheet-metal heat shield so I did not have to remove the upper O2 sensor and out with a couple of bolts. As my goal replacing the rusted down-pipe; I did not care if I ruined the down-pipe. I expected to get the bottom cat bolts out on the bench. ... No such luck. Broke one off. Ended replacing the cat. The studs look like they were installed in the flange before the cat was welded together. It was like it was designed to assemble easy at the factory; the possible repair/replacement was not even a consideration. (maybe a consideration; they wanted it as difficult as possible ).
chuck

My episode with the lower cat bolts went like this. I was able to separate the lower pipe from the cat with the 3 bolts remaining intact. But of course the remaining portion of the studs ended up too short for the replacement lower pipe flange, and they were also much smaller in diameter than the 1/2" inch holes in the new flange. So I decided to chop off the 3 bolt/studs at the cat flange and drill holes for 3 new bolts, which I inserted from the bottom up, anchored by nuts inside of the cat flange. This ended up working, but also was really time consuming to complete the job.

In retrospect, I believe there is probably a very good, and so much simpler alternative (which of course didn't occur to me at the time). This alternative would require that at least 1/2" of decent threads remains on all 3 studs, after the old pipe is removed from the cat. If those threads are present, then it should be a simple task to buy threaded couplers which fit those threads. These couplers would serve the dual purpose of providing anchors for new bolts inserted from the down pipe side, and also fill up the 1/2" or so holes that most new down pipes will have.

There are probably specialty step-up couplers available which would allow larger bolts to be used for greater strength and stability. And it may be necessary to grind down the couplers a bit, in order to fit the down pipe holes, but that would be a nit when compared to all of the hoops I had to jump through.

Wish I would have been able to take a Mulligan on that one, and try it the other way.