300E Catalytic Converters - PeachParts Mercedes-Benz Forum

stormyc88 · #1 03-29-2011, 08:54 PM

Hi all,

I've been searching around for new catalysts for the 300e, and I have two questions:

1. What is a good brand (aside from paying through the nose at the dealer)?

2. I have seen pictures of ones that have the two pre-cats on the headpipes and ones that don't. My car has them, but does it matter if I do away with them?

I'm going to be getting new stainless mufflers from timevalve, and since they no longer make the converter as well, I need to go somewhere else for that.

Thanks in advance for the help!!

-Chris

Hit Man X · #2 03-29-2011, 10:38 PM

Precats are for cold starts only. CIS is not very efficient, let alone on a cold start.

Just PM someone parting a 300E and see if they will sell the cat section. You need to be prepared to shell out ~$225 or more as that is the scrap value area for them. 'David Hendy' on the board is parting out a bunch of W124s.

Most aftermarket cats do not last very long and I find it odd your OE assembly died. How did you come to this conclusion? Did you have massive coolant/oil use for an extended period of time? Or did you simply fail emission testing?

stormyc88 · #3 03-30-2011, 03:39 PM

Quote:

Originally Posted by Hit Man X

Precats are for cold starts only. CIS is not very efficient, let alone on a cold start.

Just PM someone parting a 300E and see if they will sell the cat section. You need to be prepared to shell out ~$225 or more as that is the scrap value area for them. 'David Hendy' on the board is parting out a bunch of W124s.

Most aftermarket cats do not last very long and I find it odd your OE assembly died. How did you come to this conclusion? Did you have massive coolant/oil use for an extended period of time? Or did you simply fail emission testing?

Firstly, thanks for the replies!

My original cats aren't plugged and I guess they still scrub the exhaust ok, but with brand new mufflers, I figured a new cat setup couldn't hurt, especially after 215k miles.

-Chris

stormyc88 · #4 03-30-2011, 03:52 PM

By the way, how does one go about gutting their catalysts? I guess you have to cut it open and then weld it back together? I have no idea how to weld.

oldsinner111 · #5 03-30-2011, 03:59 PM

cut pipe so you can use a long bar of steel to break up material.Becareful when using hammer.

JimFreeh · #6 03-30-2011, 04:30 PM

Quote:

Originally Posted by oldsinner111

cut pipe so you can use a long bar of steel to break up material.Becareful when using hammer.

Usually there is a flange connection close enough that you can drop the cat and break out the ceramic matrix with a bar. I use a piece of rebar, with one end ground to resemble a flat blade screwdriver. Chuck the cat up in a vise and carefully tap out the matrix.

Makes a nice faux cat.

Jim

alabbasi · #7 03-29-2011, 10:58 PM

Muffler should be able to install a universal cat, magnaflow is a good brand.

ps2cho · #8 03-29-2011, 11:00 PM

Just chop them they are not necessary. As long as the main cat is in good condition, you are fine. I passed the CA smog perfectly fine on my wagon with the precats gone and a new high flow Magnaflow main cat.

Jim_P · #9 03-30-2011, 09:24 AM

Quote:

Originally Posted by stormyc88

Hi all,

I've been searching around for new catalysts for the 300e, and I have two questions:

1. What is a good brand (aside from paying through the nose at the dealer)?

2. I have seen pictures of ones that have the two pre-cats on the headpipes and ones that don't. My car has them, but does it matter if I do away with them?

I'm going to be getting new stainless mufflers from timevalve, and since they no longer make the converter as well, I need to go somewhere else for that.

Thanks in advance for the help!!

-Chris

Chris,
Just hollow them out if they are clogged as of Jan 2011 all pre ODBII (1996) models are emissions exempt in NY. They will still do a visual inspection to see they are present, but they did away with the Dyno emissions tests.

-Jim