The Catalytic converter warranty is only 80K miles or 8 years whichever comes first, at least on my 1999.

If your vehicle is getting near that number of miles you might want to inspect your convertors, even if you can not hear an exhaust leak. If they have a hairline crack in the weld bead you may not be able to hear them leaking because as the metal expands the crack decreases in size.

My driver's side converter cracked on the top so it was not visible from below. However, there will most probably be some exhaust gas stains on the heat shield immediately above the convertor. See photos below.


This is what the shield looked like after I cleaned it.



This photo shows the shield before I cleaned it off. The stain is most visible on the top near the location of the crack in the convertor. If any part of your heat shield is discolored you may have an exhaust leak. You might also what to compare the color of the shield on the other side of the vehicle and see what it looks like as far as color.



This photo shows the hairline crack in the weld bead. It has been cleaned in preparation of TIG welding which I going to have done on Monday.


I can't figure out why it cracked, other than excessive heat, as there is very little air circulation above the convertor because of its proximity to the heat shield. But then on the other hand the passenger side has not cracked, at least not yet.

I really don't want to get in to manufacturing, design or quality issues since I don't think that's really helpful. I just want others to have MB pay for their convertor should they fail within the warranty period.

I huge thanks to Gilly who walked me through the process of removing all the stuff that needed to come off to remove the convertor which in case anyone is wondering is not just a small round chamber, but a lenght of pipe with three chambers that runs from the exhaust manifold to the muffler, about four and one-half feet.