Trap Oxidizer recall - PeachParts Mercedes-Benz Forum

stephenc03 · #1 05-17-2008, 02:57 PM

So I have two questions regarding my 85 300SD. First, would the trap oxidezer make it difficult for the engine to start? The car runs fine once it starts and idles good, but sometimes trying to start it takes a few cranks. I replaced the glow plugs...i know they work and that they are getting power. I have a new battery 850 CCA and 1000CA. I just replaced a starter that was loosings its power. I am thinking the reason that the starter went bad is beacuse the person who owned it before me killed the starter over a period of time because of the TO. Also, I schedualed an appointment with the mercedes dealer to take advantage of the TO recall. What approach should i take. I have a feeling that these mechanics wont know anything because all the mechaincs nowadays plug a computer into the car and change the part that is broken. Is there a mercedes document that i can refer the service department for verification? thanks
-Stephen

Jeremy5848 · #2 05-17-2008, 03:46 PM

Your car originally came with a "trap oxidizer" that was changed under warranty every 30,000 miles at no charge to the owner. After a few years, Mercedes replaced the "trap oxidizer" with the "trap catalyst." This permanent replacement for the trap oxidizer was also installed at no charge. If your car still has a trap oxidizer, your dealer will replace it with the newer trap catalyst for free. The dealer will run your VIN in his computer, which will tell him whether it has already been done.

Another option (state smog inspections excepted) is to remove the trap and replace it with a piece of straight pipe. That will be at your expense but eliminates the thing entirely and gives you better fuel economy and performance. Another way to eliminate the trap is to replace the entire intake and exhaust system with one from the "Federal" version of your car.

One of the risks of the trap is that it is ahead of the turbo. Any junk it sheds can damage the turbo. Some people have gotten a new turbo for free as part of the factory recall campaign (this also applies to the '86-87 cars with an OM603 engine). My Mercedes dealer had no problem with the trap recall for my '87 300D-T (a slightly different procedure) and I indeed got a new turbo and a complete new exhaust system for free.

If the trap (either kind) becomes clogged with soot, the engine won't breathe properly. That could make the engine harder to start but also will affect performance and fuel economy. Even with the trap you should be getting low 20's for mileage. My 300D-T with trap catalyst does about 20-21 around town and 24 on the road. The dealer has a test that involves measuring the back pressure at the junction between the exhaust manifold and the trap. Too much pressure means the trap is clogged.

How long are you allowing the car to glow before starting? I often wait for longer than the time when the light goes out, especially if the engine is cold. Another possible cause of hard starting is poor compression but I suppose you don't want to go there.

Jeremy

stephenc03 · #3 05-17-2008, 04:08 PM

I let it glow for the full 30 seconds to make sure that I am getting proper glow. I am pretty sure that it has good compression because it idles good and performs well on the road. it has a little bit of blow by but when I start it it has a huge cloud of black smoke that comes out the tail pipe....and it doesnt smell like raw fuel...i assume this is from the trap oxidizer. Also does anyone know what it looks like or has pictures. I am aware that it looks like a odd shaped football which is on there, but now that you mention a trap catalyst...what does that look like. Now I dont know what i have. I just thought they replaced it with a straight pipe. I'm in california does that make a difference? thanks
-Stephen

Hit Man X · #4 05-17-2008, 04:20 PM

If it's in the downpipe now, just gut it out.

If MB will still replace it on the 617, I'd do that... but if not, just convert to Federal emission manifolds.

charmalu · #5 05-17-2008, 04:56 PM

From my understanding if it has this part# A 126 490 34 14 it is the trap catalist. It is the up grade from the trap oxidizer.

I had mine replaced at the dealer, and they did the up grade. car ran better after the replacement, but milage was 24 hwy and no acceleration at the higher altitudes.

removed it and up graded to the Federal set up. now out on the hwy we get 27 - 30 + mpg.

If you do the up grade, I recomend buying a new down pipe. I found a used one, guy charged me $100.00. lasted about 4 yrs, the flex part cracked. new is $125.00 - $130.00.

Charlie ☺

JimFreeh · #6 05-17-2008, 05:05 PM

My OM603 experience is that the trap, if plugged, will not affect the startup. No backpressure at startup, only when you try to accerate.

I could get the engine started, but it had no power, due to the increased backpressure. Tons of black smoke, no power, that is the symptom of a plugged catalyst.

My solution was to remove the oxy cat and rod it out with a piece of rebar sharpened to a point.

Car still runs great.

Jim

stephenc03 · #7 05-17-2008, 05:15 PM

So I have a straight pipe that comes off the turbo that goes down under the car but before that there is some type of trap/football looking thing. I couldnt find the niumber on the trap. does anyone have pictures? thanks
-Stephen

blackestate · #8 05-17-2008, 06:47 PM

that is the trap. And the number will tell you which it is. Mine had the number so it was almost readable. Large and stamped in the heat shield.
I also removed mine, and the car performs much better. But I do not live in CA or have to pass somg tests.

How long since your last valve adjustment? Does the turbo spin freely?
Black smoke at start up does not sound right. And if there was a restriction it would cause more issues at higher speeds.
You could always loosen the trap and see if it starts easier.

dagObx · #9 05-17-2008, 08:23 PM

Quote:

Originally Posted by blackestate

How long since your last valve adjustment?

The 603 has hydraulic lifters - no adjustment for the valves.

Jeremy5848 · #10 05-17-2008, 08:28 PM

Quote:

Originally Posted by dagObx

The 603 has hydraulic lifters - no adjustment for the valves.

I do not think the '85 300SD has an OM603 engine, think it is the older OM617 with mechanical lifters.

dieseldiehard · #11 05-17-2008, 11:24 PM

Quote:

Originally Posted by JimFreeh

My OM603 experience is that the trap, if plugged, will not affect the startup. No backpressure at startup, only when you try to accerate.

I could get the engine started, but it had no power, due to the increased backpressure. Tons of black smoke, no power, that is the symptom of a plugged catalyst.

My solution was to remove the oxy cat and rod it out with a piece of rebar sharpened to a point.

Car still runs great.

Jim

my experience has been that a plugged trap will absolutely make a 603 incapable of starting, it won't even idle! I removed the Nasty Tap Oxidizer on my Blue '87 300Dt and replaced it with one from a wrecked car in order to get the car down to the dealer for its Trap Replacement Campaign (installing the Cat and a straight pipe in place of the Trap) and that made the car run absolutely like new! My story is somewhere in the archives if you want to do a search.

Then there was a fellow that showed up here on the ShopForum that was trying to solve a problem with a 603 back East, it wouldn't run worth beans. He tried everything people had suggested (the normal GP's, filters, tank screen, lift pump, etc etc) then I piped up and suggested that the Trap might be culprit and a few days later he came back and voila! a plugged Cat!

My mechanic friend had a customer that had a plugged CAT on a 603. The car ran really poorly. Loosened the exhaust line and it came to life.

In my case and the fellow back East the cars had been driven very short distances and parked most of the time, never getting up to operating temp. That is an important clue to remember if your troubleshooting a poor running diesel, there really is something to Italian tune ups!

dieseldiehard · #12 05-17-2008, 11:31 PM

Quote:

Originally Posted by blackestate

that is the trap. And the number will tell you which it is. Mine had the number so it was almost readable. Large and stamped in the heat shield.
I also removed mine, and the car performs much better. But I do not live in CA or have to pass somg tests.

How long since your last valve adjustment? Does the turbo spin freely?
Black smoke at start up does not sound right. And if there was a restriction it would cause more issues at higher speeds.
You could always loosen the trap and see if it starts easier.

CA doesn't have any smog tests on diesels. They don't even have vehicle tests unless at the time of transfer to a new owner or from out of state, and they really don't look at anything much except maybe to see its a car and it has a diesel engine in it (if your registering a diesel for the first time here) or the smog crap is its a gasser.
Thats why there are cars with cracked windshields, no brake lights, one dead headlight, etc. running around all over the place here. One guy had no breaks, the shoes were down to bare metal and he slowly ran up behind me and bumped my bumper . Due to a language problem I couldn't tell him in so many words he needed to get the POS off the street.

minimike1 · #13 05-17-2008, 11:34 PM

Is the trap oxidizer just a catalitic converter? I've got 3- 1985's and wondering. I guess I should call the dealer with the vin's and see if I need to bring them in. Does this replacement program have an expiration date signaling me to hurry it up and call?

dieseldiehard · #14 05-17-2008, 11:37 PM

Quote:

Originally Posted by blackestate

(cut)

You could always loosen the trap and see if it starts easier.

Before removing the Trap on the 603, (its impossible to run the car without it because it won't have a turbo without it unless you happen to be so lucky to have the bypass pipe) you can remove the large plug at the front of the manifold that is shown in the FSM as where they put a temporary exhaust backpressure tester (with MB tool # provided) most mechanics just listen for the engine to idle better with the plug out. You sure wouldn't want to run very far with it off!

Jeremy5848 · #15 05-18-2008, 12:03 AM

Quote:

Originally Posted by minimike1

Is the trap oxidizer just a catalitic converter? I've got 3- 1985's and wondering. I guess I should call the dealer with the vin's and see if I need to bring them in. Does this replacement program have an expiration date signaling me to hurry it up and call?

The purpose of the trap is to catch soot that would otherwise make a black cloud when the engine is first started and is cold. The soot deposits out in the trap and later burns off when the engine warms up. In the 1985 cars with the OM617 engine made for the California market, the cars originally had a "trap oxidizer" that was replaced every 30,000 miles on warranty. After several years, Mercedes replaced the oxidizer with the "trap catalyst" which is a permanent replacement, also at no charge to the owner. Your dealer can check your VIN and tell you the status of each of your cars.

Note that the OM603 engines have a different procedure in which the trap cat is replaced by a straight pipe and a small catalytic converter is placed in the exhaust stream after the turbocharger, also at no charge to the customer.

AFAIK, both recalls are still in effect. My 603 conversion wasn't done until last year.

Jeremy