Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.
A bad air filter on a carbureted or fuel-injected engine can do more damage to your engine than you may think.
These may be symptoms of a clogged air filter:
- hard-to-start engine
- reduced engine power
- poor acceleration
- increased fuel consumption (more frequent gas tank fill-ups)
- black smoke at the tailpipe
- increased emissions
A clogged air filter will lead to:
- buildup around internal engine components
- damage to internal components
- oil and compression leaks
A car air filter prevents dust, debris, contaminants, and abrasives from reaching the intake manifold, cylinders and valve train. Thus, a clean air filter helps provide a good supply of clean, fresh air to the engine for an efficient combustion process. But as vehicle mileage goes up, trapped particles build up around your air filter. Gradually, the air filter becomes more of a barrier to the passage of air. Then, your engine works harder and consumes more fuel to get the air it needs. Dust and abrasive particles are forced through the filter, accelerating the wear on internal parts, and causing engine performance and service life to drop.
According to the US Department of Energy, an obstructed air filter reduces engine power and fuel economy by as much as 11 percent.
And that's not all. Once the air filter wears out, airborne contaminants find their way into the engine. Contaminants can not only damage an air flow (MAF) sensor, but act like sandpaper inside the engine, where they become lodged in tight clearances, scratching pistons, cylinder walls, piston rings, bearings, and other main components. Next thing you know, your engine is leaking oil and compression. By then, you have an expensive repair that could've been avoided by spending a few dollars at the right moment.
So replace your car air filter at the recommended intervals, or sooner if you drive on dusty roads frequently.
This guide tells you how to check and replace the air filter on your vehicle. In most vehicles, replacing the air filter only takes a few minutes; on some models it may take a little longer when the filter is hard to reach. You may need a screwdriver.
I. Check the Air Filter
II. How Do I Change the Air Filter?
III. How to Change the Cabin Air Filter
IV. Preventive Maintenance
I. How Do I Check the Air Filter?
Checking the air filter is a simple process. But you need to be careful when removing components. The air filter is part of the air induction system. Ductwork and other parts are easy to misalign or damage when not properly moved or replaced. When removing the air filter from its housing or air cleaner assembly, learn how the different parts fit together so that you replace them in the proper way.
1. Locate the Filter Housing
Open the hood and locate the filter housing or air cleaner assembly.
- On older vehicle models with a carburetor or Throttle Body Injection (TBI) system, look for a round- or oval-shaped metal case towards the top and back of the engine compartment. This is the air filter housing. The lid has one or two mounting wing nuts.
- On newer vehicles that use some type of multiport fuel injection system, look for a black plastic ductwork assembly around the top of the engine compartment. That's where you'll find the filter housing, a rectangular box (cold air collector box) attached to the air duct that connects to the throttle body.
2. Uncover the Air Filter
Remove the lid off the air filter housing by unscrewing the one or two wing nuts, or flipping the spring clips at the side of the assembly, depending on your particular model. Then, lift off the cover.
On some vehicle models you may need to use a standard or Phillips screwdriver, open-end wrench, or pliers to gain access to the air filter. Also, you may need to unplug one or two electrical connectors. Keep track of any fasteners and electrical connectors you may need to deal with so that you replace them in their proper place when finished.
Watch out for screws, dirt, or small parts that may fall through the carburetor, TBI plate, or air inlet. If necessary, block the throttle valve or duct opening with a clean rag.
3. Take Out the Filter
Most filters come in round, panel or conical shapes. The filter has a paper element as the filter media held by an orange or red plastic frame. Remove the filter from the housing. If your car uses a flat, pleated air filter, note in which direction the filter sits so that you install a new one correctly.
4. Check and Clean the Area
Carefully check the housing and connecting duct or hoses for damage like cracks and burns. Fix or replace components as needed.
Remove dust and debris from the cover and inside the filter housing using a damp rag and a vacuum cleaner, if necessary. On models with a plastic housing, handle the lid and casing with care during your cleaning procedure. It's easy to damage plastic components and end up with an air leak that could let dust and dirt into the engine.
5. Evaluate the Filter
If your filter is due for replacement, according to your car manufacturer, replace the filter. Look up the service schedule for your filter in your car owner's manual or vehicle repair manual. If you don't have the repair manual, you can buy an inexpensive, aftermarket repair manual at Amazon, like this Haynes manual. Haynes manuals come with step-by-step procedures, photos and illustrations for many projects like maintenance, troubleshooting and repairs for your particular vehicle make and model.
Examine the filter element. It's okay if the filter has lost some of its original color. However, if you see tears, or signs of water or oil, replace the filter.
Hold up the filter against a strong light. Or position a bright flashlight behind the filter. The light should shine through the filter. If the light can't go through the filter and the element looks dark, you need to replace it.
If the filter is dirty, don't try to knock off dirt or dust by banging the filter on the floor. It's hard to free enough fine trapped particles to make the filter reusable. And reusing a clogged filter will only lead to poor air flow and engine performance.
II. How Do I Change the Air Filter?
Choose a New Filter
After removing the old filter, match the old filter to the new one. They should have the same physical size and configuration. Use quality or premium air filters for better engine protection. Most air filters are inexpensive and do a good job.
If you live in an area with high humidity, you may want to try a filter with a high percentage of synthetic fiber or one treated with resin, which makes it more resistant to moisture.
On the other hand, if you frequently drive on dirt roads, dusty areas, or within the city, consider using a foam-type air filter. These filters are treated with oil and have a higher dust absorption rate than regular paper filters. A drawback of oil-treated filters is that if some oil reaches the mass air flow sensor or MAF (if your vehicle has one), it may interfere with the proper operation of the sensor. Pay special attention to this if you use washable filters that you can re-oil.
Install the New Filter
After cleaning the inside of the filter housing, and it dries completely, install the new filter. Look for any marks on the filter that may indicate the position the filter should be installed. For example, if one side of the filter is marked TOP, this side should face up.
Put Everything Back
Replace the housing lid and make sure that it seals properly. Otherwise, you'll have an air leak and dust particles will find their way into the engine where they'll cause much damage. Secure the lid and other components with the wing nuts, clips or screws. Replace the ductwork and any other parts you had to remove.
III. How Do I Change the Cabin Air Filter?
All internal combustion engines use an air filter, but only some vehicle models come equipped with one or more cabin air filters. This filter removes allergens, dust, debris and other pollutants from the air going into the cabin when you turn on the air conditioner or heater. Consult your car owner's manual for the location of this filter, if necessary, and the recommended service schedule.
To replace the cabin air filter:
- Locate the cabin air filter housing. It's usually located under the dashboard (around the glove compartment), or next to the firewall (inside the engine compartment). Consult your car owner's manual or repair manual.
- You may need to remove a few bolts to gain access to the filter.
- After removing the filter, clean the filter housing from dust and debris using a damp rag or vacuum cleaner.
- Install the new filter in the housing.
- Replace the lid.
On some models, the cabin filter can be washed and reuse, mostly carbon- and cloth-type filters. Consult your car owner’s manual for the instructions on how to wash the filter.
IV. Preventive Maintenance
If you replace the air filter on schedule, you will improve engine performance and power, fuel economy and service life. Thus, you'll have fewer repairs to deal with later. An air filter doesn't cost that much and takes just a few minutes to replace, so you're getting a lot in return when you check and service this component. So take a moment to check the air filter at each oil change, whenever you are performing routine maintenance on your vehicle, or need to open the hood for inspection.
In the owner's manual, car manufacturers recommend replacing the air filter about once a year, or every 30,000 miles, depending on your particular model. This schedule is designed to give you time to install a clean air filter before the old one starts to have an adverse effect on your engine. So replace the filter at your manufacturer's recommended interval, or sooner if you usually drive in a dusty environment.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.