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-   -   Catalytic converter and "pre cat" on '83 380SEL (

Rkc 10-26-2000 07:40 AM

What is the best and least expensive way to check and maybe cleanout the catalytic converter(and pre cats) on my 380? I have been told that these could be the reasons for the slugishness and rough idle.
Is this something I could do myself?
I have a good friend that owns an independent muffler shop. Will he know what to do? What is required to check these items. Maybe someone has had the same problem. Thanks for your help.

stevebfl 10-26-2000 08:01 AM

There are various methods to determine the usefulness of catalytic convertors. One that lends its self to a non shop setting is this: run the engine at idle and measure the manifold vacuum, then raise the engine speed to 2000rpm (unloaded) and measure the manifold vacuum. The vacuum readings at 2000 should be greater.

I have only done this on good cars as I only read it on iATN last year. I at first doubted that the vacuum would be higher. I was wrong. Catalyst restriction is not a yes or no answer though and I personally am acquiring a data base (experience level) on good engines and then hopefully on some plugged ones as we see them.

I have seen them so plugged that if I could get to 2000 I would have had zero vacuum. I have also seen them so plugged the car wouldn't run.

Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Ashman 10-26-2000 06:31 PM

had an 85 190e that the cat became so clogged the car died, restarting it was fine and the car revved fine in neutral, but the moment ya went into a gear and put your foot down, the car would barely move.

Had the cat replaced and it was fine until the tranny went out several months later.

Of course at the time I was much younger and didn't know how to take care of a car....


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