Pushing an air filter past its useful service life is a bad business decision. A dirty or plugged air filter restricts the flow of air to your engine, upsetting the air to fuel ratio. Diesel fuel cannot burn completely, resulting in a loss of engine performance and fuel economy.
Unburned fuel also contaminates the lube oil, reducing its effectiveness and service life.
Even worse trouble can occur through carelessness while replacing a filter element. If the filter does not seal completely or the media is punctured, dirt can get into the engine. There, it mixes with oil and causes damage to cylinder walls, rings, valves and other internal engine parts. The engine will lose power, burn oil, and, eventually, need a complete overhaul. According to Baldwin Filters, a leading manufacturer of heavy-duty filters, an engine can be ruined in as few as 500 miles without proper air filtration.
High-efficiency, dry-type air filters made with pleated, cellulose (paper) filter media, are standard on today’s engines. They require less service and are much more efficient than the old oil-bath filters, says Baldwin, which offers more than 1,200 different heavy-duty air filters. Different cellulose formulations, resins and chemical additives produce filter elements for specific applications. Air filters become more efficient at filtering out contaminants after a layer of dirt has built up on the outer surface of the filter media.
Filter manufacturers use various methods to restrict the movement of the pleated media for improved performance, extended element life and increased dust-holding capacity. Baldwin uses a proprietary PermaPleat construction to maintain the pleat spacing and to prevent bunching of the pleats. Air filters manufactured by Luber-finer feature dimples or “pleat-locks” along the edge of the filter media to stabilize the pleats.
Air filters for diesel engines are available in several styles. A radial seal design features molded polyurethane or rubber ends that function like o-rings to make a positive seal in the filter housing. Radial seal filters make installation easy because they do not involve changing gaskets. Conventional types using heavy-duty primary and secondary filter elements typically have metal ends and gaskets for sealing. Conventional housings can be adapted to use radial seal filters.
Since the amount of dirt suspended in the air varies from place to place and season to season, service intervals for air filters also vary. Driving in extremely dusty conditions or taking in excessive exhaust soot can quickly plug up a filter. Symptoms that an air filter is clogged include:
Engine starts losing power
Fuel consumption goes up
Black exhaust smoke seen
Filter manufacturers and engine makers recommend using a restriction gauge that monitors the condition of the air filter and indicates when to change it. These gauges show how much life a filter element has left by measuring the amount of vacuum created when air is drawn through the filter. When all of the filter’s capacity has been used, the indicator shows a complete vacuum. The gauges can be mounted directly on the air intake system, on the firewall of the engine compartment or in the dash. The Filter Minder restriction gauge from Engineered Products is available with a dash warning light.
Adding a turbocharger to a naturally aspirated engine may require changes to the intake ducting, Baldwin observes, since more free-flowing clean air is needed by turbocharged engines. The induction system should provide enough intake capacity to meet engine requirements for airflow, avoiding sharp bends and constrictive ducting. It should be installed in a clean location, away from exhaust flow, road grime and water splash.
Servicing Air Filters
Baldwin recommends that you follow these procedures when replacing the air filter element on your truck:
Turn off engine before removing filter
Wipe off top cover, then remove and inspect gasket. The gasket is an important seal and should be replaced annually.
Lift out element carefully to avoid dropping dirt into the engine’s air intake.
Use a clean, moist cloth to wipe up any dirt in the housing.
Inspect housing sealing surfaces for irregularities caused by dents or corrosion.
Install new filter element and reassemble in reverse order.
Warped housing lids should be replaced to ensure a complete seal. Check air duct joints to make sure they are tight because dirt can find its way into the engine through leaky ducts.
Old air filters reveal a lot, and they should be inspected carefully before disposal, notes Baldwin. Black, oily soot indicates that the air intake is located too close to the exhaust and should be moved. Rust on the filter’s metal parts indicates that water is being drawn in with air. Check the location of the intake and make sure the water-venting ports in the air induction system are clean and free of obstruction, says Baldwin.
Luber-finer, another leading filter manufacturer, advises against pulling the air filter element out of the housing to inspect it, then replacing it if it appears to be clean. Dirt can be dislodged and spill into the air intake throat of the engine. Plus, a visual inspection of the element can be misleading. A dirty-looking filter may still have considerable service life remaining, and a clean-looking filter might be completely clogged with dirt.
Other filter service tips from Luber-finer include:
Check the old element for uneven dirt patterns. That signals a leak or gasket-sealing problem. Identify and correct before replacing element.
Make sure the gaskets seat properly. If you can’t “feel” the seal, recheck sealing surfaces as well as the product number of the filter. It may be too short for the housing.
Don’t ignore a worn or damaged cover gasket. If your filter model calls for a new gasket every time, use one. Otherwise, replace as necessary.
Don’t substitute filter elements. Elements that look identical can vary in length by fractions of an inch, making a positive seal impossible.
Don’t rap an element to clean it. You can’t shake out embedded dirt; you’ll damage the element trying. Replace it with a new element.
Generally, manufacturers advise against cleaning and reusing air filter elements since it is impossible to remove all of the built-up contaminants. The cleaning process can also damage the filter and lead to engine damage.
Extended Service Filters
Fleetguard offers a standard line of heavy-duty air filters and a Magnum line that has a reference with the extension M. Magnum filters with the same dimensions as standard filters contain more square inches of media for expanded dust-holding capacity and longer life.
Racor air filters from Parker Filtration use water-repelling synthetic media that the company claims
can trap up to eight times more contaminants than pleated-paper filers, eliminating soot plating, salt and water ingestion, and surface loading. The filters also eliminate moisture-related problems, such as icing and corrosion, and they will not prematurely clog from the oily carbon soot in exhaust fumes, says the manufacturer.
Donaldson Company manufactures extended-service Endurance air filters in 35 different sizes to fit the company’s air cleaner housings. The filters are made with proprietary EOM fine fiber media technology, which provides extended maintenance intervals for on-highway trucks. According to Donaldson, EON fibers have submicron diameters and small interfiber spaces, resulting in more contaminants being captured on the surface of the media and lower restriction than filters with larger cellulose fibers.
Endurance air filters hold up to five times more dirt than cellulose air filters, the company says. Operators who change air filters at 150,000 miles can go 300,000 or more miles before replacing them, says Donaldson. He notes that Endurance filters have reached over 400,000 miles with their restriction still within acceptable limits in field tests with large fleets.
Air filter life can also be extended with the addition of a precleaner, a component designed to remove 80 percent to 90 percent of airborne contaminants before they reach the air filter. Precleaners can provide significantly more air filter life in certain applications, especially in environments with high amounts of airborne debris. All heavier-than-air contaminants, including dust, insects, leaves, wood chips, snow and sand, are expelled.
The Power Ram precleaner, which sells for about $300, has also produced a 5 percent increase in fuel economy in one test fleet. It has also produced an extended air filter life of up to six times more than filters in trucks without precleaners, says Maradyne Corp., the manufacturer. Self-powered and requiring virtually no maintenance, the Power Ram can be installed in less than half an hour. A rotating blade inside the metal housing causes incoming air to spin. Centrifugal force isolates the contaminants, which are expelled through discharge ports by a high-velocity, air-powered rotor.