Diesel oxidation catalyst

[RobertBolinger]

Does anybody know if any special maintenance will be required for the diesel oxidation catalyst (catalytic converter) on the 325/600? I'm wondering if the trapped soot will have to be flushed out somehow??

 

[Joseph Donnelly]

The soot loading from the new engine will be extremely low, especially compared to the 1994-97 models that used an earlier style cat. I did not see any trap door, etc. at the introduction event. However, I admit I didn't inspect it very closely. I consider it unlikely that a soot trap and removal/maintenance schedule would be present.

 

[nickleinonen]

Originally posted by Joseph Donnelly

The soot loading from the new engine will be extremely low, especially compared to the 1994-97 models that used an earlier style cat. I did not see any trap door, etc. at the introduction event. However, I admit I didn't inspect it very closely. I consider it unlikely that a soot trap and removal/maintenance schedule would be present.

i wonder if fueling box's will be no go for people with stock exhaust w/cat still there??? more smoke will come from the fueling box and that will plug up the cat quicker...

 

[fbaurley]

A DOC or diesel oxidation catalyst, uses aq platinum coated ( and other precious metals)ceramic subtrate much like a conventional catalytic converter in a gasoline engine. The way a Doc works is that the paltinum oxidizes the gases and soot that are going through it, therefore Co becomes Co2 , No, becomes No2, and Hydrocarbons & soot are burnt. The major problem with a DOC is that they require a fairly high exhaust gas temp to make the reaction work. Therefore if you are driving under extremely cold temperatures and say just short in town driving the Doc never heats up enough to cause the reaction to work. Therefore you can soot the filter of the DOC. What can happen is when you then get out on the highway and the Doc gets up to operating temp. the reaction can overun, due to the large amount of fuel( which is the soot thats trapped) My experience (from working at an exhaust/ emissions company), is that the Doc sometimes destroy itself, buy burning out the ceramic insides. Theses things can get extremely hot . One thing that will be interesting is to see how close they put the DOc to the turbo. I wouldnt be surprised if it is with 3 to 4 ft. From my experience Id be a littel leery of putting on a Box that would make a lot of smoke from the fear of having a doc melt down, but usually it justs burns the core out , and renders it useless. Doc's have been aroound, and tried on urban buses for a few years, if you can keep them up to temp, they are effective.

 

[Doubleclutch]

This forum never fails to amaze me! You guys would be NO fun to play "stump the dummy" with.

It sounds like the DOC is going to be the weak link in the 50 states legal banner. I hope it will be covered by the emission blanket. Thanks for the input, fbaurley.

Greg

 

[RobertBolinger]

Great info

Thanks for all the info-my 2 cents is that if it does burn out it doesn't matter unless:

1. It puts codes in the ECM that cause the CE light to come on-is there even a sensor that could do this?

2. It clogs up and causes poor engine performance/mileage

3. You live in a state that has a sniffer test for diesels

Here (NC) the newer OBDII stuff does not get a sniffer test unless it was located in the original 10 emissions counties-I don't think diesels even get tested at all...

 

[Joseph Donnelly]

The earlier cat was covered by emissions warranty; as a major component of emissions system, the new one will have to be covered. It is located in line with the tail housing of the transfer case.

 

[RobertBolinger]

Joe, could you respond to the "unrelated question" I just posted in this forum? I meant to post it under this thread...

 

[Vaughn MacKenzie]

My 2003 stock makes as much smoke/soot under load as my 2001 HO stock, but of course my new truck makes more power. After a road trip to central California and back towing a small trailer my quarter panel & bumper end has a decent layer of soot.



Vaughn

 

[JHayward]

DOCs don't do anything for NOx, check the Fleetguard website. NOx is probably going to be reduced, in part, by retarded timing.

 

[raychem]

Kill the kitty, thats all I have to say!

 

[fbaurley]

Actually a DOC will increase the NOX, because it changes the Nitrogen N to No or No2. so therefore theyve got the engine down pretty low on Nox, but it has probably increased the particulate matter and Co, which the DOC takes care of. Its all kind of a balancing act to meet the emission level, when you decrease one you increase the other.

 

[JHayward]

fbaurley,



That's what I was refering to. There is a NOx / PM tradeoff, so it seems like they are reducing NOx in the combustion chamber via timing retard, at the expense of PM, then the higher PM is treated in the DOC. This will have a negative impact on BSFC...

There's hope, though...

http://www.anl.gov/OPA/news03/news031128.htm

If this works and is commercially viable it could be very cool... good milage, low NOx, low PM, high power!



Happy New Year!