Hello All. '97 S420 / M119.981 here.

I've been following some recent threads about plugged cats, and noticing that my car was a bit down on power I decided to do some of the checks that were recommended. I have been noticing that the right side cat has been rattling for a while so I know it will need to be replaced eventually, but I think the time has finally come. Besides the rattle, I have noticed these other symptoms as well:

1. When the engine is at operating temp, I notice a diesel-like clatter/tapping coming from the lower right side of the engine bay. It's not really loud, but it's noticeable.

2. I took some temperature readings with an infrared thermometer and discovered that the right side is significantly different from the left:


Inlet-- Left:367 deg F Right:277 deg F
Outlet-- Left:467 def F Right:265 deg F

My best guess is that the right side cat is dead & partially plugged.

So, on to the questions. . .

1. Is my diagnosis correct?

2. Can the average, mortal, DIY mechanic replace a cat at home? Any "gotchas" to watch out for?

3. Can anyone recommend a good source for a replacement cat? I'd prefer OE if possible.


Thanks!

__________________
"It's not about how fast you can go, but how well you can go fast."

Bob in Richmond

'97 S320 (LWB), Ruby Red Metallic, 73k miles
'97 S420V, Smoke Silver Metallic, 155k miles