Secondary cats
#1
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Join Date: Mar 2014
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2013 C350, 2013 GL450, 2018 G550 4x4^2
Secondary cats
are these really secondary cats or just another resonator, I have done research and have seen someone who said there was no cat filament in this so called secondary cat. I have never heard a car to have four cats. Can anyone confirm this
#2
Which car are you talking about? V6 and V8 exhaust commonly have primary and secondary catalytic converters. You need one set very close to the exhaust manifold to get hot right away and deal with the startup rich mixture hydrocarbons. Typically there is also a larger unit slightly downstream for higher RPM exhaust volumes, but they are not effective until they get warmed up. Cars with dual exhaust may have 3 or 4 cats.
Diagram of V8 AMG Exhaust:
Picture of AMG Exhaust:
Diagram of V8 AMG Exhaust:
Picture of AMG Exhaust:
#4
Senior Member
This picture is of my 2013 c350 v6 3.5L. It has secondary cats, 4 total. My porsche boxster 3.2L H6, for sure had 4 cats. 2 of which I removed and could clearly see the honeycombs.
#6
MBWorld Fanatic!
Just showing a picture doesn't confirm that there is catalytic material inside. I had my "2nd cats" removed, and they were just small resonators. You could see through them, 2.25" diameter the whole way through.
#7
Senior Member
Richard,
Do you have pics of the inside. Trying to convince my shop that they are not truly cats or they would actually have sensors but they will not cut them off. maybe with a couple of pics I can make that happen
Do you have pics of the inside. Trying to convince my shop that they are not truly cats or they would actually have sensors but they will not cut them off. maybe with a couple of pics I can make that happen
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#8
Senior Member
secondary cats rarely ever do have sensors unless you drive a lambo, then maybe. my boxster for sure did not have sensors for the secondary and confirmed they were cats by looking in. The function of a secondary cat acts as a double filter while the primary cats heat up to operating temperature.
#9
MBWorld Fanatic!
Sorry. I tossed them without taking pics years ago. I'm sure they could stick a rod down the pipe and actually see that there's no obstruction caused by catalytic material. Also, it may help to just go to another shop and don't call them cats.
#10
Super Member
.. You can also grab a grinder, 2 pieces of pipe, and call a local welder!
Probably a lot cheaper too! And nobody telling you what to and not to do to your car!
It's like a half-DIY.