How To

Look for More than Dirt!

By Larry Hammer
Technical Services

Filter Replacement Intervals

If you look at the air filter replacement intervals recommended by the vehicle manufacturers, you will be amazed by the variations in vehicle mileage. Some recommend a filter replacement at 10K miles and others may vary from 30K to 50K miles. Personally, I am more concerned about the environment the vehicle has been operated in rather than mileage. Some turbo-diesel applications require an air filter replacement every 3K miles, especially those vehicles operated on construction sites or heavy farm use.

A Sealed System

Many technicians only focus on the condition of the filter. They are looking for contamination and the accumulation of debris that can restrict air flow into the engine. A close examination of the air filter housing and its ability to seal is imperative. Thoroughly examine for any evidence of dust bypassing the filter, such as dust trails across the filter seal or dust accumulating inside the air filter housing on the clean air side of the filter. Make certain all clamping devices are intact and the plastic latches are secure. A sealed system is especially important on vehicles equipped with a mass air-flow (MAF) sensor. The MAF sensor measures the amount of air passing through the sensor and provides data to the powertrain control module (PCM). Any air entering the system without passing through the MAF sensor is false air, which results in a deteriorated engine performance. Contamination of the sensor can affect the grams per second reading. Do not touch the MAF sensing element or allow cleaners, solvents or lubricants to come in contact with the sensing element, as they can render the sensor inaccurate or inoperative. When making a filter installation, make certain all debris is removed from the filter housing. Examine the filter housing for deformity or damage from intense heat, which will allow unfiltered air to enter the system. Police cars and taxis have a history of distorted air filter housings due to the intense heat encountered during long periods of idling.

Diesel Applications

On diesel applications, a restricted air filter may result in a power loss, the air filter collapsing or coming apart and being pulled into the turbocharger. Sometimes the filter will lose its seal with the housing, or it gets pulled into the housing, allowing contaminates to be drawn into the engine, resulting in major turbocharger or engine damage.