Technical Reference
Engine Components Need Protection Engine liquid circuits (lube, fuel and coolant) are designed in all shapes and sizes, both simple and complex in design, and they all need protection from damaging contamination. Abrasive particles enter the system and, if unfiltered; damage sensitive components like pumps, bearings and injectors. It is the job of the filter to remove these particles from the fluid flow to help prevent premature component wear and system failure. As the sophistication of engine systems increases, the need for reliable filtration protection becomes ever more critical.
Another wear area can be the fuel injector needle seat.The needle mates to a seat which is the sealing surface to control the flow of fuel to the combustion chamber. If a particle becomes trapped between the needle and seat it can hold the needle open. In addition, this particle can wear the surface – causing it to become irregular and disable the sealing function of the needle.This can impact the fuel delivery performance of the injector.
How Contamination Damages Precision Parts
This cutaway view of a simple oil valve illustrates how particles damage components. In normal operation, the spool slides
Close-up of worn fuel injector needle seat.
Types of Contaminant Many different types of contamination may be present in engine fluids, causing various problems. Some are: • Particulate (dust, dirt, sand, rust, fibers, elastomers, paint chips) • Wear metals, silicon, and excessive additives (aluminum, chromium copper, iron, lead, tin, silicon, sodium, zinc, barium, phosphorous) • Water • Sealant (Teflon®* tape, pastes) • Sludge, oxidation, and other corrosion products • Acids and other chemicals • Biological, microbes
back and forth in the valve body, diverting oil to one side of the valve or the other.This type of valve is typical in engine oil control circuits. If a particle lodges between the spool and valve body, it will erode small flakes from the metal surfaces. As these flakes are moved back and forth by the action of the spool, they can roll into a burr that jams the spool and disables the valve. In the pictures below, we see examples of how contamination can impact fuel injectors. Fuel injector nozzles are small passages that deliver an evenly distributed fine mist of fuel to the combustion chamber.These fine passages can become plugged with contamination.
Close up of new (left) and worn (right) fuel injector nozzles.
48 • Engine Liquid Filtration
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