What is it with DEF?

[Gonzo42]

Just what is the Diesel Exhaust Fluid (DEF) ? What does it do and why do I need it? This is my first diesel and I never heard of it.

[Gonzo42]

I have a question in to Winnebago and hope to hear from them shortly.

I have heard back from Eric at Winnebago and he confirmed my unit does not use DEF. I was sure is didn't but now have confirmation.

[Dufus]

As to how it works: Diesel exhaust fluid (from a separate DEF tank) is injected into the exhaust pipeline, the aqueous urea vaporizes and decomposes to form ammonia and carbon dioxide. Within the SCR catalyst, the NOx are catalytically reduced by the ammonia (NH3) into water (H2O) and nitrogen (N2), which are both harmless; and these are then released through the exhaust.

[broark01]

In essence, SCR technology allows manufacturers to reduce NOx emissions after they are created by means of converting them into safer compounds. While it is seemingly inconvenient and costly to keep the DEF tank filled, SCR technology has many benefits.
 
• Increased fuel economy when compared to non-SCR equipped trucks with diesel particulate filters. SCR equipped trucks are able to operate under leaner conditions and take advantage of a diesel's ability to operate within a broad spectrum of air-to-fuel ratios. Under light load conditions, and SCR equipped truck can run much leaner while adhering to emissions regulations. This ability had been previously shrouded, as NOx emissions are greatest when an engine is operated on the leaner side of the acceptable air-to-fuel ratio spectrum.
• Reduced strain on the EGR system, since the EGR system is no longer the sole combatant against NOx emissions. This promotes a more reliable, problem free EGR system.
• Reduced strain on DPF, since the engine's are able to run leaner and an engine produces less particulate matter at such operating conditions.
• Cleaner emissions. Nitrous oxides can cause or increase the effects of a number of respiratory problems, as well as contribute to the formation of acid rain.

[wny_pat1]

It appears you have a 2007 model year Mercedes Benz Sprinter engine. I don't think MB used DEF in your engine in 2007. Best to be asking a Mercedes Benz dealer. The big thing is using the specified, required, lube, i.e. synthetic motor oil. MB, like most european diesels, are very fussy about that!!!

I think you will get much better information on your Sprinter MB diesel at the Sprinter Forum.

[Old-Biscuit]

Gonzo42 wrote:
Added to our profile:

MOTHER SHIP
Winneago View 24H (2007 Chassis, 2008 Body)3.0 L Diesel V6 bought used with 24K miles.

Has a DPF (Diesel Particulate Filter) System
Most common type have a regeneration cycle.
Vehicle needs to be driven at highway speeds to accomplish regeneration.

Your owners manual will address the DPF, use and regeneration

Download manual.........HERE

[Deb_and_Ed_M]

As someone who always hated diesels due to the stink and noise - I LOVE our 2011 F-350. Runs quietly, doesn't stink at all - and gets 12-13 mpg towing the 5er and 22 mpg or so when cruising without the trailer. Has GOBS of power. On ours, the DEF tank opening is next to the fuel opening - our fuel door is just wider. We found it's easiest to simply pump it at a commercial fuel island when we need it - the price has been around $2.69/gal. We wait until we get the dashboard notice that it needs to be refilled ("in 800 miles") - then we top it off. We tried simply adding a gallon that we bought, but for some reason, that didn't register with the trucks "brain" - and the owner's manual implied it needs to be "filled up".

Minimal hassle for a much "nicer" truck, IMO!

[F105]

F105 wrote:

Me Again wrote:

F105 wrote:


Depends on your definition of "new big rigs."

Our 2012 3/4 ton Ram with the Cummins 6.7L diesel doesn't require DEF. But I understand the 2013's and newer do require it.

We were lucky to get it in December 2012.

You were not lucky. The 6.7 from 2007.5 up to 2013 when they added the DEF feature are much more likely to have engine/turbo problems and get what is generally considered lousy fuel mileage! I would not own a Dodge/RAM/Cummins from that era! They also suffer from diesel get into the engine oil and require more frequent oil changes, as they "make oil"!

No problems so far - 16k miles.

No problems so far - 16k miles.

So no talks!

Chris

[F105]

Me Again wrote:

F105 wrote:


Depends on your definition of "new big rigs."

Our 2012 3/4 ton Ram with the Cummins 6.7L diesel doesn't require DEF. But I understand the 2013's and newer do require it.

We were lucky to get it in December 2012.

You were not lucky. The 6.7 from 2007.5 up to 2013 when they added the DEF feature are much more likely to have engine/turbo problems and get what is generally considered lousy fuel mileage! I would not own a Dodge/RAM/Cummins from that era! They also suffer from diesel get into the engine oil and require more frequent oil changes, as they "make oil"!

No problems so far - 16k miles.

So no talks!

Chris

[Me_Again]

F105 wrote:


Depends on your definition of "new big rigs."

Our 2012 3/4 ton Ram with the Cummins 6.7L diesel doesn't require DEF. But I understand the 2013's and newer do require it.

We were lucky to get it in December 2012.

You were not lucky. The 6.7 from 2007.5 up to 2013 when they added the DEF feature are much more likely to have engine/turbo problems and get what is generally considered lousy fuel mileage! I would not own a Dodge/RAM/Cummins from that era! They also suffer from diesel get into the engine oil and require more frequent oil changes, as they "make oil"!

So no talks!

Chris

[DianneOK]

We get our UREA right from Ford

[nevadanick]

The def tank has a heater. When below a certain temp the ecu knows the def is frozen and it alllows the truck to run without it for a certain amount of time so as for it to thaw.

[ddschuman]

aruba5er wrote:
I would not buy some to keep on hand. It's too avaiable and it has a made on date (code) but they want you to keep it fresh. My 2011 dura max has been back 3 times for trouble. Last time I bought some from a pump and shortly thereafter message said poor quality See instruction book. You can not drain the tank, it must be pumped out. GM dealer did all the things the co. required and they reset the computer and in a couple weeks it happened again. This time with fresh GM DEF. so far no more trouble. BUT how does it work when the stuff is FROZEN SOLID?

We had a 2011 prior to our current truck. There were lots of bugs with the 2011. Our truck was in he shop more than it was out. They finally replaced the entire tank and assembly and the problems went away. DH had to be towed twice before they took this action. We have had no problems with the our 2012 and have had it going on 2 years. We do keep DEF on hand but not like it may sound. The closest SAMs store is about 50 miles from home. We only go about every other month. Owning a HVAC business in a very rural area, DH does a lot of driving. He may replace the DEF one month and go to SAMs the next. It doesn't sit more than about a month maybe slightly longer before being used. We've had no issues thus far.

[rr2254545]

rtz549 wrote:
Get it at the pump for ~$2.79

http://www.pilotflyingj.com/def-at-the-pump

Much written on here about the subject - problem at buying at the pump is that most of us have the fill on the passenger side of the MH and pumps are on the driver side - including all Flying J that I have seen

[aruba5er]

I would not buy some to keep on hand. It's too avaiable and it has a made on date (code) but they want you to keep it fresh. My 2011 dura max has been back 3 times for trouble. Last time I bought some from a pump and shortly thereafter message said poor quality See instruction book. You can not drain the tank, it must be pumped out. GM dealer did all the things the co. required and they reset the computer and in a couple weeks it happened again. This time with fresh GM DEF. so far no more trouble. BUT how does it work when the stuff is FROZEN SOLID?