Engine/Transmission (1998.5 - 2002) Urea?

[Makensmoke]

I have been "out of the loop" with all the changes to our engines for the last... 5 years? I'm more than happy with my 2nd gen and don't have time to stay on top of all the politics constantly choking our industry.



I was asked today if new Dodge's need DEF like the competition. I see they use Urea, can someone take a second or two to catch me up in a brief summary?



Thank you in advance.

 

[rMetzger]

Diesel Emissions Fluid is a solution that contains urea. It's for NOx reduction, and, therefore, acid rain reduction.

Since air is 80% nitrogen, and 20%oxygen, you can't keep nitrogen out of your combustion chamber. Since a Diesel runs with minimal fuel, and an excess of air, there will be a huge number of oxygen molecules in the combustion chamber with no hydrocarbons to react with. But, they will, at temps of 700*F or higher, react with nitrogen molecules.

This is how NOx emissions exist in the first place. Super-hot air causes the two components of air to react, even when you have no "fuel".

Urea-fogging into the exhaust stream reverse the NOx reaction, restoring O2 and N2.
the truck's computer monitors conditions, and expends DEF as needed.

Trivia point: a mechanic I know has received several DuraMax engines for non-warranteed rebuilds, due to operator error.

Apparently, the urea reservoir in a Chevy is under the hood, and people have been loading that tank with washer fluid. Methanol is not interchangeable with urea, so the proper reaction does not occur, and the truck's computer subsequently sends very wrong fueling instructions to the engine, which results in catastrophic failure.


Cruel though it may be, my first thought was, "always knew them chevy boys were dense"

 

[rMetzger]

I didn't answer your actual question. Yes. The newer Dodges require DEF. They just mark and locate the reservoir in a safer spot, where washer fluid is less likely to get there.

 

[Road Dog]

I thought the pickups DO NOT use DEF and the C&C DOES USE DEF. Different markets, different tuning and why not try out different emissions systems.

 

[n7gxz]

Road Dog is correct. The pickups do not use DEF but do have DPF (Diesel Particulate Filter). The C&C have DEF and the filler cap is behind the cab on the drivers side.



Kevin

 

[Makensmoke]

Good stuff, thanks again.



Doesn't the DEF "clean" the particulate filter? I'm guessing a particulate filter must manually be cleaned or changed if you have no regeneration feature like i've heard of to self clean?

 

[RustyJC]

The Duramaxes use DEF (urea) but still have regen for the DPFs. They use a 9th fuel injector in the exhaust system so that oil dilution isn't a problem for them during regeneration - something I wish Cummins would have done. Since they don't use as much EGR with the DEF to meet the NOx emissions, sooting isn't as much of a problem, and with less EGR and fewer regeneration cycles, they don't suffer as much of a fuel consumption penalty.



Rusty