What is Diesel Exhaust Fluid? Who needs it?

Here are a few quizzes:

When will emissions rules produce better trucks?

If you answered, “What about the 2008 Clean Air Act Standard or the Clean Air Act Standard”, you can stop reading. You probably already know everything in this post.

For the rest of you, the answer is, “When it becomes clear that diesel exhaust, or DEF, is an important part of the solution to emissions problems.

Everyone who’s ever driven behind an older bus or semi-belching smoke and diesel exhaust knows the problem: Diesel engines are dirty and smelly.

That’s the price we pay for power and torque that the gasoline engine can not be the same.

DEF brought the price down.

This is the reason.

Diesel Penalty …
The combustion takes place on the gasoline engine cylinder when the spark ignites a mixture of fuel and air.

A diesel does not use sparks. Instead, it greatly compresses the slimmer air fuel mixture.

This is a high level of compression that causes the fuel to ignite.

Unfortunately, the compression ignition process also produces higher emissions of harmful nitrogen (NO) and particulate oxides.

… And the solution
To meet air quality standards that call for lower NO levels, manufacturers adopt an approach called “selective catalytic reduction,” or SCR.

With SCR, a small amount of liquid is sprayed into the exhaust stream. The chemical reactions that occur convert NO emissions into nitrogen and harmless water.

Actually, coming out of a solar exhaust using an SCR may be cleaner than going into the machine in the first place.

That’s very helpful in 2010. It’s important in 2017 when regulations call for a 90% reduction in the allowable nitrous oxide from the muffler.

The magic responsible for the reduction is DEF: a 32.5% ammonia solution in ionized water. And it is a powerful (and somewhat misunderstood) solution to a serious problem.

What you need to know
DEF lives in a reservoir in your vehicle, which usually accommodates about five gallons.

In GM’s heavy duty truck, customers get about 1,000 miles per gallon of DEF. Heavy transport or towing can increase the level of DEF consumption as well as on fuel.

In consumer vehicles, DEF can be consumed at a speed of about 2.5 gallons per 800 miles of driving.

DEF tank must be kept at least partially full at any time. Many diesel engines will not operate more than 4-5 MPH if the tank dries. Other people will not run away at all.

Fortunately, it should not be a problem, as most manufacturers provide gauges, digital readings or “low-level liquid” warnings on IP.

And keep the tank terminated easily and relatively cheaply.

Manufacturers have built DEF services into their scheduled maintenance specifications. So the liquid can be terminated when the owner brings their vehicle to a scheduled service.

And DIY-ers can easily maintain their own DEF level, just like a washing machine fluid. The liquid is readily available at dealerships, truck stops and auto parts, usually around $ 5 / gallon.

Truck stops often have DEF pumps on their fuel island.

Perhaps the biggest misconception about DEF is that this is an obstacle to performance.

Actually, the opposite is happening. Manufacturers have tuned their diesel engines so that DEF really optimizes combustion.

That means better fuel efficiency, more power, less machine wear and high reliability.

And there is another myth:

DEF evaporates quickly. (Actually, it evaporates very slowly.)

This is a bottleneck on mileage. (In fact, it offers better mileage than most other emission reduction systems The manufacturer estimates a five percent mileage.)

It’s poisonous. (Actually, this is less toxic than many other liquids used in the vehicle, and has been used for many years in commercial trucks and ag industries.)

Some Warnings
While DEF is good for newer machines with DEF systems, there is no point in old diesel engines lacking such a system.

And DEF should not be added directly to fuel. It’s corrosive and can reduce your fuel system to a worthless piece.

That’s why some manufacturers give access beneath to the system. The others provide a separate filler neck next to the fuel cap.

Either way, if you suspect your fuel has been contaminated with DEF, do not ignite the ignition to the accessories, which can activate the fuel system.

Instead, take the withdrawn vehicle, without starting, to the workshop. Ask them to flush the fuel tank, then again enjoy the power of diesel, torque, and possible reliability