Myth vs. Fact

The Filter Minder ® Graduated Air Filter Indicator makes it easy for you to tell when it's time to change filters.

The myth is that an automotive air filter should be changed about every 6,000 miles, or when it "looks dirty." The fact is, a certain amount of dirt in an air filter actually increases its filtering efficiency by reducing the size of the holes in the filter media which helps stop smaller dirt particles. This means that instead of a maximum life of 6,000 miles, the typical air filter may actually last anywhere from 60,000 to 100,000 miles! Filters do not plug based on time or mileage. They plug based on the operating environment of the vehicle.

The Filter Minder ® takes the guesswork out of when to change your air filter because it doesn't care how dirty the air filter looks or how long it's been installed. It only cares how well the filter is working. When the filter gets restricted, the Filter Minder ® will let you know.

Air Filter Service Indicator

The Filter Minder ® is installed on the air cleaner or air induction piping so that it has access to clean filtered air (between air filter and engine).

The air filter service indicator is a simple device that accurately measures the air induction system filter restriction. It measures and remembers the highest restriction at maximum air flow, which is called full load condition. This condition occurs during hard acceleration, or while pulling a trailer, etc.

The indicator is easy to read. As the air filter plugs, and restriction increases, the yellow position indicator moves in the clear window and locks at several points. When it reaches and locks in the red zone, the air filter should be changed and the indicator reset to zero. Reset the indicator by pushing the yellow reset at the end of the indicator.

Another type of air filter service indicator is the Filter Minder ® Single Position Service Indicator. The clear window turns red when maximum recommended restriction has been reached.

Every air induction filter system has a clean filter or initial restriction reading. Depending on air flow volume, filter media, and air filter size, there may not be enough restriction to show a reading on the gauge with a new filter, or the position indicator may move one or two positions. Do not be alarmed if there is some restriction with a new filter as this is not unusual.

Air filters usually show low restriction through most of their service life. As the air filter nears the end of available service life, filter restriction will increase more rapidly, and the yellow position indicator on the Filter Minder ® will move more rapidly towards the red zone. High humidity or rainy conditions may slightly increase air filter restriction.

The Filter Minder ® is calibrated in inches of water vacuum per the engine manufacturer's recommendations.

Use of the Filter Minder ® helps maximize filter service life, prevents excess fuel usage from overly restricted filters, and saves on operational costs.

How Filters Work

An air filter is made from paper or other media to trap dirt and other foreign particles as dirty air passes through the filter. There are tiny holes in the media that allow the air to pass through, and stop most particles.

Air filters are not 100 percent efficient at trapping dirt particles. Most new air filters are 97-99.9 percent efficient A small amount of dust or dirt can pass into the engine. As the air filter builds a dust film, the holes in the media become smaller, and the filter becomes more efficient at trapping dirt.

As the filter traps dirt, it is more difficult for the air to pass through the filter, and restriction increases in the air induction system.

The Filter Minder ® measures restriction or vacuum. The air filter service indicator is calibrated per engine or vehicle manufacturer’s recommendations.

The air filter should be serviced when the position indicator of the service indicator approaches or reaches the red zone.

Use of the Filter Minder ® helps maximize filter service life, prevents excess fuel usage from overly restricted filters, and saves on operational costs.

When To Reset The Filter Minder

The Filter Minder ® should be reset whenever the service indicator is checked to determine air filter restriction or when a new air filter is installed. Push the reset button at the end of the service indicator, and the position indicator will return to zero.

If the air filter has not been replaced, the position indicator will return to the same reading when the vehicle is driven under normal driving conditions.

High humidity and rainy conditions can make air filter restriction increase more than dry air conditions. The Filter Minder ® reading may show a slightly lower or higher reading after being reset and the vehicle operated depending on atmospheric conditions.

Troubleshooting

Air Filter and HVAC Service Indicators and Gauges:

To determine if the Filter Minder ® is working properly, if the window on a single position service indicator is showing red, or the position indicator on a graduated service indicator is showing in the window, reset the service indicator by pushing at the end of the indicator. If it resets to zero, the service indicator is operating properly.

If there is no position indicator showing in the clear window:

Remove the service indicator.

Pull a vacuum on the service indicator until the position indicator reaches red zone. If the position indicator does not lock in the red zone, replace the service indicator. Push the reset at the end of the service indicator to reset to zero. If it does not reset, replace the service indicator. Again, pull a vacuum on the service indicator until it locks in the red zone.

Re-install the service indicator.

Push the reset at the end of the service indicator. If it resets to zero, the service indicator and fitting assembly is working properly.

If the position indicator fails to reset fully to zero, check the air cleaner fitting, as the safety filter in the fitting may be plugged. If plugged, replace the fitting. Replacement fittings with safety filters are available from Filter Minder ®. Some fittings are welded to the air cleaner, and cannot be removed. In this case, it will be necessary to drill a hole through the fitting, and add a new adapter fitting with safety filter. Be sure to collect the metal shavings to prevent them from getting into the air induction system. Note: Some systems use rubber grommet mount service indicators, which do not utilize a fitting.

Air Filter Switch Service Indicators:

Check the mechanical operation of the Filter Minder ® by following the above instructions for service indicators and gauges.

To check the operation of the switch, pull a vacuum on the Filter Minder ® until the position indicator locks in the red zone. The warning light in the dash should illuminate.

If the warning light fails to illuminate, proceed in checking proper operation of the switch, wiring, and light bulb per normal electrical maintenance procedures.

Switch Indicators are available in normally open or normally closed switch designs. See label for switch details.

The Filter Minder ® is a durable product that may last the lifetime of the vehicle.

For severe applications, it is recommended that the Filter Minder ® be checked periodically to make sure it is working properly.

The Filter Minder ® air filter service indicator measures vacuum in the air induction system in 'inches of water vacuum'.

The Filter Minder ® is calibrated per engine or vehicle manufacturer's recommendations.

Most diesel engines operate at a maximum 20 to 25 inches water vacuum under full load.

Gasoline engine calibrations can vary depending on the engine size and air cleaner design. Small gas engines (2-5 HP) should usually limit restriction to 3 inches maximum, 6-25 HP should limit filter restriction to 8" maximum, and most gasoline engine powered automobiles 20 inches maximum. Some vehicles with the Filter Minder ® as standard equipment may use a higher calibration than the above guidelines. If in doubt, contact Engineered Products Company for recommendations.

Diesel suction fuel filters are usually monitored in inches of mercury. The maximum restriction is typically 10-12 inches of mercury.

Cleaning the Filter Minder ®

Use a mild soap solution to clean the Filter Minder ®. Do not use petroleum based solvents or other chemicals, as they may attack the polycarbonate clear housing causing it to crack and craze. Gauge contact with brake fluid and ethylene glycol should be avoided.

Typical Air Filter Restriction Readings

Air filter restriction usually remains low through most of the filter service life, then increases rapidly at the end.

FAQ

Frequently Asked Questions

1. Should an air filter be changed frequently?
An air filter that has built up a dust film is more efficient at stopping dirt and foreign particles, which will keep the engine cleaner. It is best to leave the air filter in place until restriction is noticed on the air filter service indicator, then change the filter.

2. What if the Filter Minder ® position indicator does not move for a long period of time?
The Filter Minder ® reads the restriction in the air induction system. Air filters usually have low restriction for most of their service life, and the position indicator will not move very much. Then, as the air filter reaches the end of available service life, filter restriction increases rapidly, and the position indicator of the service indicator will move faster towards the red zone.

3. Why doesn't the Filter Minder ® show restriction even though the air filter looks dirty enough to change?
Although an air filter may look dirty, it is impossible to tell the true condition by visual inspection. An air filter that looks dirty may have much of its service life remaining. Air filters have low restriction for most of their service life, then restrict rapidly at the end. It is best to leave the air filter in place until restriction is noticed on the air filter service indicator.

4. How long does an air filter last?
Air filter service life depends on operating conditions. An air filter may restrict in a few hours/miles, or last several hundred hours/100,000 miles or more. Monitoring the air filter with a Filter Minder ® service indicator takes the guesswork out of air filter maintenance.

5. Does horsepower decrease as air filter restriction increases?
Dynamometer testing of horsepower at various filter restrictions has shown that horsepower remains constant as air filter restriction increases up to the maximum level of filter restriction recommended by engine and vehicle manufacturers. Engine horsepower can decrease when air filter restriction exceeds the engine or vehicle manufacturer's recommendations.

6. Does fuel consumption increase as air filter restriction increases?
Fuel consumption remains constant as air filter restriction increases, until it reaches a certain point. Testing by independent companies suggests a slight increase of fuel consumption with a diesel engine when air filter restriction reaches 17-18 inches water vacuum. However, the fuel consumption may not be severe. The 17-18 inches restriction is only seen at full load conditions, which may be an infrequent condition. Full load condition includes hard throttling, pulling a trailer, passing another vehicle, etc. Air filter restriction reduces when these conditions end. The engine may be operating most of the time at lower restriction levels cruising at highway speeds, which would not affect fuel consumption. If there are concerns about excess fuel consumption, the air filter can be changed at lower restriction levels.