OxyCat - PeachParts Mercedes-Benz Forum

Johnhef · #1 06-16-2008, 07:54 PM

Ok so who has messed with the trap recall replacement parts on a 603 engine?

I'm curious about my oxidation catalyst as to what it does, what it looks like inside etc and can it get clogged. My 87 is noticibly slower over the last month or so and I'm trying to figure out whats causing it. 0-60 in 17.5s at best.

I've got the idea in my head that the exhaust might be partially blocked and so I'd like to learn what I can about it and hopefully rule that out.

#2 06-16-2008, 08:08 PM

It filters/burns some of the soot in the exhaust.

sixto · #3 06-16-2008, 11:31 PM

It can get clogged. You can replace it with a straight pipe or an oh-so-rare trap oxidizer exhaust system. For testing, cover your ears and run with the downpipe disconnected from the turbo.

Sixto
87 300D

dieseldiehard · #4 06-16-2008, 11:35 PM

The Nasty Trap Oxidizer, very prone to plugging up, esp if the car isn't run hard and often to heat it up good.
I have heard of a case where a Cat on an '87 was plugged and lowered engine power.
I also hear that you can drill out the matrix in either a trap or Cat using a long bit, presumably to send the contents out for an analysis

dieseldiehard · #5 06-16-2008, 11:40 PM

Quote:

Originally Posted by Johnhef

Ok so who has messed with the trap recall replacement parts on a 603 engine?

I'm curious about my oxidation catalyst as to what it does, what it looks like inside etc and can it get clogged. My 87 is noticibly slower over the last month or so and I'm trying to figure out whats causing it. 0-60 in 17.5s at best.

I've got the idea in my head that the exhaust might be partially blocked and so I'd like to learn what I can about it and hopefully rule that out.

There is a service bulletin that shows a exhaust pressure gauge (MB of course) attached at the front of the manifold, theres a big (24mm?) plug and removing that will also allow some exhaust to dump out for testing purposes (it will be very loud!)
But I have to wonder how come you haven't had the Factory replace it with the Cat under the Open Campaign, its still open I hope!???

Trap Oxidizer Campaign

Jeremy5848 · #6 06-17-2008, 12:02 AM

Quote:

Originally Posted by dieseldiehard

There is a service bulletin that shows a exhaust pressure gauge (MB of course) attached at the front of the manifold . . .

The spec is 2 bar (30 psi) maximum back pressure at that test port. A higher back pressure means the trap is plugged up.

The test port is also a good place for an EGT thermistor, BTW. It's a 10mm thread (1/4-28 pipe is a good approximation).

Jeremy

C Sean Watts · #7 06-17-2008, 08:31 AM

Quote:

Originally Posted by Johnhef

Ok so who has messed with the trap recall replacement parts on a 603 engine?

I'm curious about my oxidation catalyst as to what it does, what it looks like inside etc and can it get clogged. My 87 is noticibly slower over the last month or so and I'm trying to figure out whats causing it. 0-60 in 17.5s at best.

I've got the idea in my head that the exhaust might be partially blocked and so I'd like to learn what I can about it and hopefully rule that out.

but I do have the recall replacement. It looks just like a catalytic converter inside. About 15% of the passages are clogged on the downstream side (haven't seen the upstream yet) so I'll be 'unclogging' it soon.

babymog · #8 06-17-2008, 11:10 AM

The recall replacement is under the car in the downpipe, right? I'm not sure of your post.

dieseldiehard · #9 06-17-2008, 05:49 PM

Quote:

Originally Posted by C Sean Watts

but I do have the recall replacement. It looks just like a catalytic converter inside. About 15% of the passages are clogged on the downstream side (haven't seen the upstream yet) so I'll be 'unclogging' it soon.

Is this what you are referring to? 1987 300SDL Turbo

Johnhef · #10 06-18-2008, 10:16 PM

My trap oxidizer was long gone, replaced by a dealer around 1997 in Boise Idaho according to the VMI, what I was asking about is the Oxidation Catalyst, located under the car in the downpipe.

I've got a downpipe off a 300SD and the part of the resonator pipe up to the kidneys I'm going to adapt to it for testing. The 123 downpipe is just a little too tall to bolt up without modifications although it will fit somewhat. That along with the resonator pipe I have off a 208 and the rear muffler pipe/section off a E300, I think I should be able to make something to replace my stock exhaust

Jeremy/DDH, thanks for the info about the bulletin and the spec, I will try that first, does it list the special tool p/n? I want to check to see if we have one.

Jeremy5848 · #11 06-18-2008, 10:32 PM

Quote:

Originally Posted by Johnhef

. . . Jeremy/DDH, thanks for the info about the bulletin and the spec, I will try that first, does it list the special tool p/n? I want to check to see if we have one.

I've seen pictures of the pressure gauge but not the part number. IMHO, it's just an ordinary pressure gauge, you could use one for gas pressure from a hardware store, welding shop, etc. Even a turbo boost gauge would work so long as it will go up to 30 psi (2 atmospheres).

Jeremy

#12 06-18-2008, 11:05 PM

Quote:

Originally Posted by Johnhef

I've got a downpipe off a 300SD and the part of the resonator pipe up to the kidneys I'm going to adapt to it for testing. The 123 downpipe is just a little too tall to bolt up without modifications although it will fit somewhat. That along with the resonator pipe I have off a 208 and the rear muffler pipe/section off a E300, I think I should be able to make something to replace my stock exhaust

Why not just put a straight pipe in placeof the cat?

Jim Wickham · #13 06-19-2008, 11:48 AM

I am the case of lowered power in an 87 with clogged cat. mine would start and run fine but when asked to go it would just crawl along so I put a boost guage on a port at the intake manifold and ended up without even a twitch in the needle when asking for full power in drive. I took the down pipe off and took it for a spin.... difference was incredible... absolutely out of this world power in comparison. Made it a whole new car. punched the cat and took the innards to my local scrap yard.

Jeremy5848 · #14 06-19-2008, 11:55 AM

This must not be unusual or Mercedes wouldn't have put in the test port.

sixto · #15 06-19-2008, 12:06 PM

Exactly. I don't recall a manifold test port on the 93 SD which doesn't have a trap or cat. At least I'm pretty sure it doesn't have a cat.

The 90-91 350s don't have a trap or cat either but they use the 86-87 manifold with trap replacement pipe.

Sixto
87 300D