Mystery exhaust part.
 

Can anyone tell me what the part circled in red on the photo below is? It's on an 83 380sel that I just had a custom cat back system installed on.

After everything was all buttoned and sounding great, I discovered there is very small leak coming from somewhere near the top of it. The outside is surrounded by a sheet metal shield and the oxygen sensor screws into it. Thanks.

http://www.pairofshorts.com/benz/mbexhaust.jpg

Thats the front cat pipe.

It is a cat and the second one is also a cat. In other words it has 2 cats. However when you look up the parts they are considered one part.
paul

If there is a leak you need to take it back and get it fixed. It might be leaking where it connects to the manifold. Or could be a defective part I suppose.

I chose to have a custom cat back system fabricated because parts of the original system had been cut off (including the back flange on the converter) and everything was welded back together. The pipes were still in pretty good shape and it was determined that the converter was still good, but both mufflers were totally shot.

I've used this shop before, they do good work and are very reasonable. I figured as long as the converter was good their plan of bending all new pipes and installing new mufflers at a cost of less than $300 was pretty good. Then, if the converter failed later I could have them splice in a universal at about $500 less than one made to fit.

At this point my question is this: Does this front "cat" actually have catalyst in it, or does it just provide a place for the oxygen sensor?

The car is back at my regular independent shop and they are wondering if they can remove sheet metal shield, and assuming there's enough good metal, find the leak and weld it up without hurting the car's ability to pass emissions, which it now does with flying colors. Any ideas?

Thanks.

I wound up taking it back to the muffler shop. They removed the heat shield and welded up a 2" long crack in the first converter. I then took it back to my regular shop and they put their emmisions tester on it and it was still good. BTW, the muffler shop says they could see honeycomb through the crack before they welded it, so there is catalyst in it.