What does the DEF metering valve do?
The metering valve holds back fluid to the front brakes until enough pressure is created to overcome the return springs inside the rear drums. It is also known as a “metering block.” The metering valve is plumbed into the system immediately after the Master Cylinder.
Where is the DEF metering valve located?
The DEF metering unit is mounted on the back side of the exhaust emissions box. The arrow indicates the location of the filter on the DEF pump.
Where is the DEF pressure sensor located?
A DEF quality sensor is mounted on the side of the DEF tank. This sensor detects the Urea concentration in the DEF to confirm it is acceptable for effective dosing (approximately 32.5% Urea).
What should DEF injector pressure be?
Once the “SCR Fore Exhaust Gas Temperature” gets above 300 deg F, “DEF Dosing Device Control Mode” changes to “Urea Dosing Enabled State” and the pump kicks on. Pressure goes to around 130 PSI (I was told 120-140 PSI is normal).
What is the purpose of a combination valve?
The valve restricts how much pressure is applied to the rear brakes, without this feature the rear system would lock up and cause the car to go out of control. If the car is equipped with a disc and drum combination, then a metering valve is also needed to regulate how much pressure is applied to the front wheels.
What happens when a proportioning valve goes bad?
Since the proportioning valve decreases the pressure sent to the rear brakes, the main symptom the valve is going bad is the rear wheels locking up when the brakes are applied. Furthermore, the wheels will lock up more easily on wet surfaces. The rear brakes may feel touchy when applied even gently.
What is a DEF dosing unit?
Dosing Unit. The dosing unit, or injector, is a robust component that delivers an atomized urea and air mixture upstream of the SCR catalyst. The design allows injection in the center of the exhaust gas flow, which minimizes the risk of deposits and improves reliability.
How does a DEF sending unit work?
The DEF sending unit mounts to the DEF tank. It integrates liquid level and temperature measurement functions, and it also regulates DEF temperature via a heating function that utilizes the engine’s coolant. A urea quality sensor is integrated into the DEF sender to measure DEF concentration.
What is the purpose of DEF?
Diesel Exhaust Fluid (DEF) is a solution of urea and water that’s injected into the exhaust stream of diesel vehicles to turn NOx gases (harmful emissions) into nitrogen and water. This system is called a Selective Catalytic Reduction (SCR) implemented by vehicle manufacturers to meet EPA emissions standards in 2010.
What are metering valves are used on?
The metering valves are the fine flow adjustments. Metering valves are used for fine flow control of the fluid . It improves the braking systems of the cars. Since the metering valves are attached to the braking systems, therefore it is an important part of a car’s braking system which controls the brakes easily.
What is the meaning of valve?
Definition of valve. 1a : any of numerous mechanical devices by which the flow of liquid, gas, or loose material in bulk may be started, stopped, or regulated by a movable part that opens, shuts, or partially obstructs one or more ports or passageways also : the movable part of such a device.
What does flow control valve mean?
A flow control valve is a mechanical device used to regulate and control the flow of a liquid or gas. Typically, these control valves are non-mechanical, usually relying on the undesirable conditions of the regulated substance to open or close the valve. Occasionally, flow control valves will be regulated…