Cherry Red Catalytic Converter- S600

[cole3986]

After driving on the interstate for 40 minutes @ 80 mph I exited the interstate and came to a red light- at the light the engine had a sudden loss of power (1995 S600) - seemed to running on all cylinders just no power. I drove the car approx 1.5 miles like that then decided to pull over to see what is going on- the passenger side catayltic converter (the car has two cats) was cherry red- the entire cat- after cooling down- I started the car- same issue appears to be running on all cylinders- but is likt there is something stuck in the exhaust- like a banana - is there something wrong with the timing/ air fuel ratio- or did the cat just instantly clog ?

[Kestas]

It appears your car went suddenly rich, dumping lots of excess fuel into the engine. Did the check engine light come on? I don't think cats glow red from clogging. Do you have the dreaded brittle engine wiring harness that plagues most MBs from 95?

[cole3986]

That is what I am scared about- wiring harnass problem - no the check engine light did go on but the check engine light has not been working for a few years - (does not glow during start up).

is there a way to test whether the cat is clogged ? if the engine is running rich only one side of the engine is running rich otherwise both cats would be glowing red- if the cat is glowing red- is it ruined ? the wiring harnass is a disaster to replace so I would like to confirm that prior to ripping the exhaust apart.

I do think that a clogged/collasped cat will glow red- just never had a clogged cat- I just cannot imagine it happening all at once

[Kestas]

The cat may survive short episodes of overheat, but I don't think it's good to run it that way for a long time. Here's a couple of things you could do. Read your computer for error codes (I'm not sure how it's done on an S600). Check the engine wiring hardness for evidence of brittle insulation. If it is brittle, you wouldn't be wasting your money buying a replacement harness, regardless of whether it solves your immediate problem.

There is a way to check for a clogged cat. It involves removing an O2 sensor and checking the pressure. I forget what pressures you look for (2 psi max?)

You may want to replace the check engine light bulb.

[Gilly]

Not sure what the fault is, but a word of warning:

On this engine, it's very hard to tell if you are running on all 12 cylinders, or just one bank. The V12 is set up very much like 2 engines, 2 of many components like engine control modules, ignition systems, etc and it WILL idle very very smoothly on just one side. The usual complaint when this happens is simply "engine lacks power".

Gilly

[cole3986]

I do not have a scanner to read the computer- so I guess I need to buy one- can you recommend one ? Good advice regarding the wiring harnass- I was also going to pull some of the spark plugs to see if they are fouled ? How hard is it to replace the wiring harnass ? I will take the O2 sensor out and see if the car runs better- If the engine harnass is the problem will I get a code from the computer ? So I might get lucky and the cat maybe notn ruined assuming this is a running rich problem

[cole3986]

I do not have a scanner to read the computer- so I guess I need to buy one- can you recommend one ? Good advice regarding the wiring harnass- I was also going to pull some of the spark plugs to see if they are fouled ? How hard is it to replace the wiring harnass ? I will take the O2 sensor out and see if the car runs better- If the engine harnass is the problem will I get a code from the computer ? So I might get lucky and the cat maybe notn ruined assuming this is a running rich problem

[Kestas]

I wasn't clear in my previous post. Just taking out the O2 sensor won't help diagnose for a plugged cat. The O2 sensor is replaced with a pressure gauge to measure the backpressure.