Catalytic converter flange replacement?

[ksjdan]

Hi all,

I am currently in a process of replacing the muffler and all exhaust gaskets. When I was removing the catalytic converter, I noticed both of the flanges were badly rusted, and one of the flange actually has a crack spot. I got the entire exhaust off and took a photo of it.

I checked bmwfans but noticed there is a part number for only one of the two flanges. Is there a way I can replace the flange that is "trapped" inside the pipe?

[jrobie79]

what I did for mine, was find one similarly sized from an auto parts store, then I cut it in half with a cutoff wheel, chamfered the edges that matched up, put two halves together behind the flanged, then welded it back together....its been holding for 3 years now

[SmokeE30]

i have some old exhaust laying around with flanges if u wanted to cut and weld

[DetailAddict]

+1 on cut and weld

[ksjdan]

Thanks for the input guys. I dont have much knowledge in welding, nor have the tools to do it. So I just dropped it off at a exhaust shop today and Im going to get him a few flanges to work with. He's going to cut the pipe, insert a new flange and weld the pipe back in place. It seems like a bigger mess than welding the flange. Thoughts?

[DetailAddict]

well, it depends on how good they weld and what kind of flanges they'll be using. if you want to say compatible with other oem pieces, i would replace the broken flange. if not, hope their weld is good and keep the exhaust in alignment when done.

[ksjdan]

well, it depends on how good they weld and what kind of flanges they'll be using. if you want to say compatible with other oem pieces, i would replace the broken flange. if not, hope their weld is good and keep the exhaust in alignment when done.

He has a decent reputation so I think he can handle a simple job like this. I'm going to give him a few oem flanges. He's charging around $60.

[ksjdan]

In case anyone was wondering, I got the catalytic converter back from the welder. It looks better than I have anticipated.

Here is the result. He cut the neck of the pipe off, and rewelded from the inside. Looks almost like the way I gave it to him...but with a new flange on it.