Whether it’s in the engine oil, air, transmission, fuel line or passenger compartment, filtration is all about trapping contaminants.
The engine’s oil filter traps wear particles and dirt that might otherwise damage the bearings, rings and other wear surfaces inside the engine. The air filter keeps out dirt that could damage the piston rings and cylinders, or clog air passages in the throttle body idle air control circuit. The transmission filter prevents debris from jamming control valves and causing wear inside the transmission. The fuel filter stops sediment and rust particles that could plug the fuel injectors. And finally, the cabin air filter prevents dust, pollen and odors from entering the passenger compartment.
By stopping unwanted contaminants before they can cause trouble, filters prolong the life of the engine, transmission and fuel system. The more contaminants a filter traps, the more efficient it becomes up to a point. If not replaced, the filter will eventually clog and create a restriction. This, in turn, may cause additional problems.
A clogged oil filter may restrict oil flow to the bearings, camshaft and upper valvetrain components. This may force open a “bypass” valve that allows unfiltered oil to flow around the clogged filter. If the oil is dirty, the contaminants will be carried directly to the parts that the oil filter is supposed to protect. This will increase oil wear and may even result in premature engine failure.
A clogged air filter will restrict air flow into the engine. The choking effect can upset the air/fuel mixture causing the engine to run rich, pollute and use more fuel. A dirty air filter can increase carbon monoxide emissions and reduce high speed power.
A clogged transmission filter will reduce oil flow inside the transmission. This may cause engagement and shifting problems, or cause the transmission to slip. Slipping accelerates wear in the clutch packs and can lead to premature transmission failure.
A clogged fuel filter will restrict fuel flow to the engine and may cause a loss of fuel pressure. This can make the engine run lean, misfire and lack power when accelerating. If the filter becomes totally plugged, it may stop the flow of fuel altogether causing the engine to stall or prevent it from starting. Or, it may cause a bypass valve inside the filter to open allowing unfiltered fuel to flow to the injectors. The injectors have tiny screens in their fuel inlets, which may become clogged if the fuel is dirty.
An old, clogged cabin air filter will restrict airflow into the passenger compartment. This may cause a loss of cooling when the air conditioner is running, or reduce heater output during cold weather. Reduced air flow may also hamper the windshield defrosters from clearing the glass during cold weather or wet weather. A clogged cabin air filter can be a particularly common problem since most motorists are not even aware that their vehicles are equipped with them. In order to sell them, you’ll need to be armed with application and installation information. Not all vehicles have them, so you’ll need to know which vehicles do and which ones don’t. Additionally, cabin air filter installation can be an easy, straightforward process, or it can be a little more involved. You’ll most likely need to know how these filters are installed in order to make the sale.
Generally, cabin air filters are located under the dashboard (usually between the blower and the rest of the HVAC case), behind the glovebox or under the hood, usually near the air intake. Among these filter locations, those under the dashboard are typically the most difficult to change. Those behind the glovebox are the easiest.