Red Hot Cat!!
 

While trying to figure out why our 75 450 SL was runing awful, I noticed today that the right side catalytic converter was glowing red hot! Now, I'm guessing that this is not the preferred condition. Sound like its plugged? As I don't have to submit to emissions tests, could I knock a hole in the screens? Thanks, Dusty

A cat that is glowing red hot is being subjected to way too much fuel. It is unlikely that it is plugged, however, if the condition continues for any length of time, the inside of the cat will melt into a mass and then it will definitely be plugged.

You must correct the over rich condition immediately and/or remove the catalyst.

As only the right side cat is red hot, is only the right side bank of cylinders getting too much feul? What could cause this? Guess I need a starting point.... Thanks, Dusty

One bad spark plug or one bad plug wire on the right side will cause one of those cylinders to misfire and dump raw fuel into the exhaust.

That will light up the cat like a Christmas tree.