300D/SD aftermarket emissions controls - PeachParts Mercedes-Benz Forum

usmma2013 · #1 12-14-2016, 10:47 AM

Hey guys!
A search hasn't brought much up - has anyone explored with adding an aftermarket diesel catalytic converter or diesel particulate filter to their OM617 powered car?
HJS is a european company i've found which makes several affordable, standalone DPF & Oxi-cat designed to be added to older diesels - operating with nearly continuous burn-off. I'm sure the most difficult part would be space to install it as close to the turbine outlet as possible in the exhaust system.
Anyone have experience?

Mxfrank · #2 12-14-2016, 11:26 AM

You could probably install the DPF from a 201 or 124, but as you say you'd need to find a hot enough spot. Regen would be done by tsking the car for a high speed run. Later devices are more sophisticated, and the problem would be electronic engine controls to manage regen cycles.

SD Blue · #3 12-14-2016, 05:01 PM

It is unclear as to why you want to!!!

Even the manufacturer, after extensive testing, found that it wasn't a good idea and ended up with a recall to remove it on several models.

If you are having excessive smoke, perhaps you should check valve adjustments and timing before installing a can of worms.

Graham · #4 12-14-2016, 05:19 PM

Mercedes may have some surplus Bluetec systems

Someone told me that Mercedes Canada have about 1000 new diesels of various models just sitting. They are apparently not allowed to sell them because of lack of emission system approvals.

dkr · #5 12-14-2016, 10:10 PM

Why do you feel the need to abuse your Mercedes?

Dkr.

sixto · #6 12-14-2016, 10:22 PM

The oxidation catalyst that replaces the trap oxidizer in the 86-87 MB Diesels is beside the transmission. It should be a simple to install but expensive to purchase deal for a 123 or 126. There's always retrofitting the exhaust manifold, trap oxidizer and air cleaner assemblies from a California '85 300D/SD.

Sixto
83 300SD

Mxfrank · #7 12-14-2016, 11:07 PM

Quote:

Originally Posted by SD Blue

Even the manufacturer, after extensive testing, found that it wasn't a good idea and ended up with a recall to remove it on several models.

Not exactly. The trapox was removed from the top of the engine and relocated a couple of feet down the front exhaust pipe.

MBexh

jay_bob · #8 12-15-2016, 08:39 AM

The real rub with the original setup on the 603 is that it was located after the exhaust manifold on the engine and before the turbo. The problem with this arrangement, is that if (actually when) pieces of the catalytic material were shed from the inside of the trap ox, then they were ingested into the turbo, with predictable results.

Also the trap ox gets very hot as part of the chemical reaction that happens inside. This excess heat was getting radiated back to the turbo, the head, and most of the other things in the vicinity.

The designers placed the converter initially right out of the exhaust manifold because it works better with higher incoming temperatures. Unfortunately the unintended consequences outweighed the benefits.

The recall involved removal of the trap ox and replacing that segment of the system (between the exhaust manifold and the turbo) with a straight, insulated pipe. The converter was relocated as mxfrank said, down under the passenger's feet. This had two benefits, one is that the heat could be dissipated better due to the air flow beneath the vehicle, and also any shed debris from the converter get blown out the exhaust.

compu_85 · #9 12-15-2016, 09:02 AM

Magnaflow makes a diesel oxidation cat that's not too expensive. It would help reduce soot emissions a bit, lessen the diesel exhaust odor, and basically eliminate any VOC emissions. Summet Racing caries them: https://www.summitracing.com/parts/mpe-93006d/overview/
You'd want to mount it under the car. The closer to the turbo you can get it, the better it will work.

That setup is basically what the trap ox / DPF recall fitted to the 6 cylinder cars, and what later pre-dpf diesels (like our 99 Jetta and 04 Touareg) have. It works fairly well and takes almost no power.

Adding a DPF would be trickier because of the regen requirement.

-J

compu_85 · #10 12-15-2016, 09:04 AM

Quote:

Originally Posted by Mxfrank

Not exactly. The trapox was removed from the top of the engine and relocated a couple of feet down the front exhaust pipe.

MBexh

That's not quite the full story. The trap ox / DPF was removed, and replaced with a DOC that went under the car.

The trap ox really was basically a DPF, and the engine computer would periodically cause exhaust gas temps to go up to regenerate it.

-J

usmma2013 · #11 12-17-2016, 08:33 PM

Thanks for the replies guys!

As for the why, I believe that's self explanatory.

The '85 trap oxidizer (upstream of the exhaust turbine) did have issues with allowing debris into the turbine. I do not have any desire to go this route.

Thanks computer_85, I'll look into that DOC, that seems intriguing!

usmma2013 · #12 04-12-2017, 04:58 PM

Update for all interested:

I installed an Oxidation Catalyst at the bottom of the downpipe. I used vband clamps so I can remove and inspect in 5k miles or so, as well as change to a DPF/DOC combo when I find one that's not 800.00 or more :0

Initial impressions are smoke and smell reduced greatly. I can't see any visible smoke even shining a light in the tailpipe. Going for a rest ride on the highway tonight will tell.

(As an aside, this engine runs great to start with. Both Mercedes shops in my area were very amused when I brought it with what I thought was excessive smoke).

I typically run B70+ which has zero visible smoke, but whenever the cars been on diesel I found myself getting annoyed. So, so far so good!