Oxidizer trap is going bye bye - PeachParts Mercedes-Benz Forum

ConnClark · #1 12-29-2005, 01:51 PM

Well the oxidizer trap recall is still in effect. Scheduled to have my car inspected Dec 30th. I managed to get 23mpg on my last trip with it(400 miles all at 70), which is the best milage I have seen with this car. I think that it stayed hot enough for a long enough time to cook off some of the carbon thats plugging it up. Hopefully the cat that will be installed will flow a hell of a lot better. I'll wait until it plugs before something mysterious will happen to it ;-) .

Oxidizer traps may work on long haul trucks, diesel locomotives, and generators, however for a car driven on short trips or in stop and go traffic they are a total clusterF*** .

I'll let you all know how much my milage goes up.

lietuviai · #2 12-29-2005, 04:05 PM

Mine had a trap and the PO had it replaced with the oxidizing catalyst under the recall. I don't think it'll help you as far as power is concerned. The catalyst will still choke your engine. I didn't get really great fuel economy either. I was getting around 23 MPG's with it. It felt like a dog even after adjusting the ALDA. I got rid of the catalyst completely last year and replaced the manifolds and turbo from a fed version. That's were I noticed a real difference. MPG's went up as well as the power.

ConnClark · #3 12-29-2005, 06:29 PM

I've heard that the oxidizing cat is less restrictive than the oxidizer trap. Normally I get about 20 MPG so anything will be an improvement. Whats your milage now with federal equipment?

lietuviai · #4 12-29-2005, 10:19 PM

My mileage went up to about 25 MPG's. I did get about 27 MPG's when I didn't push it. I liked taking advantage of the extra power so my mileage suffered a little.

ConnClark · #5 02-09-2006, 11:11 AM

My month+ long quest to get my trap oxidizer replaced under recall is over. Yippie!!

I can say for certain that there is an increase in power. Will probably use the road trip to the portland get together to test the mileage. Now If I can only keep my foot out of it

Now I need to wrap the thing to keep it hot to prevent it from plugging up ( I have a grueling 2 mile commute to work so the engine doesn't even get up to temp).

lietuviai · #6 02-09-2006, 03:05 PM

WOW 2 mile commute? That much huh?

blueranger · #7 02-09-2006, 07:48 PM

here in kentucky we would beat the thing with a hammer and
break all the garbabge out of it... then we would put it back on..
and it would be hollow... exhaust would flow great then..

Diesel Giant · #8 02-09-2006, 09:42 PM

Get rid of that trap. Its a power robbing menace.

79300sdtd · #9 02-09-2006, 09:49 PM

what year is the recall for and how do i go about it?

vwbuge · #10 02-09-2006, 11:33 PM

I switched my crap over to the Fed version. I still get around 22mpg around town and a little more on the highway. Not bad considering 300,000 miles, the ALDA tweaked and the boost adjusted to around 14psi.

PanzerSD · #11 02-09-2006, 11:43 PM

What IS an oxidizing flap? What cars were they on and where? I have a Canadian 300SD 617.

GTB

lrg · #12 02-10-2006, 12:55 AM

Quote:

Originally Posted by Got_The_Benz

What IS an oxidizing flap? What cars were they on and where? I have a Canadian 300SD 617.

GTB

It's actually called a Trap Oxidizer and was installed on the OM617 engine in 1985 and the OM603 for '86-'87. It was intended only for the California market due to tougher particulate regs but there were a couple of other states that had them too. Only the '85s had the two versions of cars, Federal and California. The later cars with the OM603 all had them, regardless of state. After '87 Mercedes no longer imported diesels until a few years later when they reappeared in 49 (48?) states without a trap of any sort. If you have a Canadian car with an OM617 you most likely won't have a trap.

The Trap Oxidizer was intended to be replaced for free under warranty every 30,000 miles to be sure they didn't clog up although several dealers told me they were considered safe for much longer under most normal driving conditions. The idea was that the soot would be trapped inside and then be allowed to burn up when the car was driven enough to get the trap really hot. The use of fuel additives will cause the Trap Ox. to go bad very quickly unless you use one of the few additives formulated for them like Redline 85+. In the mid 90s Mercedes developed the Trap Catalyst that did not have to be replaced and is presumably good for the life of the car. Most of the old Traps were updated at a normal service, there was not a special recall. If the car was never taken to the dealer the retrofit may not have ever been done. It's rare but you do see some old traps on EBay cars ever now and then. On the OM 617 the new Trap Cat looks exactly like the old Trap Ox so the only way to tell them apart is by the part number on the football shaped can (which is the trap - we covered this on an old thread so you can do a search if you need the part numbers). On the later cars with the OM603 the recall replaced the whole unit with a much smaller Trap Cat which is nothing like the old can and looks more or less like a regular exhaust.

One note about mileage on the '85s. The CA cars had a slightly lower axle ratio than the Federal cars. A car with a good trap system will feel as fast as a federal car but the mileage will always be a bit worse unless you tinker with the rear end. Also, the late CA cars had a very different vacuum system which ran the emission stuff and the transmission so be careful if/when you start dismantling the smog stuff or you'll really screw things up. I can tell you there aren't many in CA anymore who really know how these systems work and when you get east of the continental divide it's unlikely anyone has even worked on one much less has a clue how to troubleshoot a CA car. Both my cars a CA cars with intact smog equipment and both have been completely trouble free. I use the right kind of additive, do the occasional italian tune-up and accept the fact the my mileage is a few mpg below the rest of you. I have 15 years and 120,000 miles on the 123 and 5 years and 50,000 miles on the 124 and based at least on my experience I'll take a rust free CA smog equipped car anyday.

That ought to cover it.

#13 02-10-2006, 02:10 AM

Quote:

Originally Posted by blueranger

here in kentucky we would beat the thing with a hammer and
break all the garbabge out of it... then we would put it back on..
and it would be hollow... exhaust would flow great then..

That works well with a cat in the exhaust AFTER the turbo. But since it's before the turbo, hollowing it out would just be a big football sized chamber for the exhaust to expand, cool and slow down. Performance would be far worse than with a clogged TrapOx.

ConnClark · #14 02-10-2006, 11:13 AM

Quote:

Originally Posted by ForcedInduction

That works well with a cat in the exhaust AFTER the turbo. But since it's before the turbo, hollowing it out would just be a big football sized chamber for the exhaust to expand, cool and slow down. Performance would be far worse than with a clogged TrapOx.

I doubt it would be worse than a clogged Trap Oxidizer. Remeber on the 86 -87 SDLs these things created enough heat and back pressure to crack the heads.

I just did a 162 mile trip yesterday all at 70. My new mileage record is 24.9 mpg . Up 1.9mpg over my previous record of 23 .

ConnClark · #15 02-10-2006, 12:05 PM

I wanted to add that the engine was quieter and didn't seem to be working as hard. Now I'm going to add my boost gauge and try and adjust the boost. It strained a bit going up one hill and I had trouble maintaining speed up it. Pushing the pedal down more didn't really help so I think the boost is low.