The Importance of Your Motorhome’s Engine Air Filter


Mike Tiojanco

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When maintaining a motorhome’s engine, most people focus on oil changes and ensuring they’re done on schedule. But changing your engine air filter regularly is just as important. Here’s why.

What Does a Motorhome Engine Air Filter Do?

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Modern motorhome engines, just like automobile engines, are built with very specific tolerances. Even a minimal amount of dirt or dust introduced into the system will reduce the performance of your engine.

Your engine air filter is your engine’s best defense against dust and dirt.

Dirt in an engine is extremely abrasive. The tolerances referenced above mean each component of an engine is engineered and manufactured with precision accuracy so that each piece fits and moves perfectly within the system.

Engine air filters can only handle a limited amount of dirt and dust. As they get older and more clogged, airflow is restricted, leading to engine overheating and other issues. It can also cause dirt to pass around the filter, potentially impacting engine components’ seal and fit and decreasing the engine’s power and efficiency.

Engines on less developed roads require more filtration. 

Your engine air filter will pick up dust and dirt if you only drive on developed highways. But many RVers these days are seeking boondocking destinations that require navigating miles of undeveloped dirt roads. 

As you’d expect, off-roading will kick up more dirt and introduce more contaminants to your engine’s air intake. If you drive an RV built for off-road travel, you should check your engine air filter more frequently than RVers that stick to paved roads. 

Whether it’s a local campground with unpaved sites, boondocking on public lands, or trekking deep into state parks, be mindful of how your route and campground selections can impact your motorhome’s engine air filter. 

Without a clean air filter, that dirt and dust won’t just end up on your hiking boots. It’ll make its way into sensitive engine compartments.

How Does a Clogged Engine Air Filter Impact Your RV’s Performance?

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So what do we mean by “reduced performance?” This can manifest itself in several ways.

Lower Fuel Efficiency

Fuel is one of the top expenses for RVing, and in the most basic sense, fuel and air are what move your motorhome down the road. When a dirty air filter reduces airflow to the engine, there’s simply no way it’s running as efficiently as possible. When it needs to work harder, you’re just burning more fuel.

Slower Acceleration

While you’re not going 0 to 60 in 2.5 seconds, slower acceleration can still be frustrating and dangerous when driving an RV. A clogged air filter can cause an engine and motorhome to feel sluggish and slow to respond when you depress the gas pedal.

Anyone who’s driven an RV knows you need extra time and space when pulling into traffic. The worst-case scenario is that you start pulling out of a parking lot, and the motorhome doesn’t respond as quickly as you expect, disrupting cars and putting you in danger of a collision.

Reduced Towing Power

Many motorhome owners tow another vehicle, or “toad,” so they can leave their RV at the campground and get around easily. Some tow boats, 4x4s, or equipment for other outdoor activities.

As we know by this point, a clogged air filter means a less efficient engine — something you’ll feel when you need more torque to pull a second vehicle. This only worsens if you’re traveling in the mountains with lots of uphill pulls to get to your destination.

How Often To Change Your RV’s Engine Air Filter

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Make it a habit to check your RV’s engine air filter every time you get an oil change. You may not need to replace it then, but it’s healthy to take a look. Checking and replacing your air filter regularly is one of the cheapest and easiest RV maintenance tasks you can do yourself

When you check your engine air filter, look inside the pleats for excessive accumulation of dirt and debris. Shining a flashlight through the filter can show how dirty it truly is. You can also hold the filter over a trash can and tap the side. 

Most air filters can be cleaned with compressed air to extend their service life. Some manufacturers recommend doing this with each oil change. But if your filter is especially dirty, it has served its lifetime, and you should replace it. 

At the very least, you should replace your engine air filter annually or every 12,000 miles. Doing so will also save you time and money by keeping dust and dirt away from more sensitive engine parts that are much more costly to repair or replace. 

RV Engine Air Filter Types

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First of all, you’ll need to consult your owner’s manual or an RV service center to acquire a compatible engine air filter replacement. RV engine air filters are not universal, so you’ll need to find a product that matches your RV’s year, make, and model.

That said, you will have some freedom to choose different types of filters, depending on your preferences. Here’s a little more about the most common RV engine air filter types: 

Cellulose Filters

These filters are made of plant-based fibers treated with resin to hold their shape and extend their life. They’re generally efficient, easy to manufacture, and affordable. Some cellulose filters are treated with a sticky substance called ‘tackifier’, which enhances their ability to attract dirt. 

Because dirt gets collected on these filters’ exterior surfaces, they become clogged more rapidly than synthetic filters. And even though they’re inexpensive, cellulose doesn’t promote airflow as well as synthetic filter materials. 

Synthetic Filters

Synthetic filters are generally comprised of various types of man-made fibers. That allows manufacturers to control fiber size to find a great balance of filtration and airflow. These synthetics are generally considered ‘depth media’, meaning they collect dirt on the exterior surface and inside the fibers themselves. 

This allows synthetic filters to collect more dirt than cellulose filters while allowing ample air to flow through the filter. While the exact design and engineering used to create synthetic filters will dictate their price, they are largely more expensive than cellulose filters. 

Open-Cell Foam Filters

These filters are made of polyurethane material with pores that are large enough to allow air to pass through but small enough to capture airborne particulates. The pore size and density are controlled in the manufacturing process, and several layers of foam of varying densities can be layered together. 

Foam filters are also typically made with a sticky tackifier to increase efficiency. While they’re fairly easy to clean, it can be hard to find foam filters that strike a good balance between airflow and filtration efficiency at a reasonable cost.  

Oiled Cotton Gauze Filters

Gauze filters can be a nice upgrade for your RV. They are made with sheets of pleated, fibrous cotton between layers of wire mesh. When an oil tackifier is applied, these filters provide slightly better fuel efficiency and performance while helping you save money over the long haul because they don’t need to be replaced as often. 

These filters can carry a high dirt load and are easily cleanable. Their only downsides are cost and the fact that you’ll need to be careful when cleaning them so as not to damage the fibers.

How to Replace Your Engine Air Filter

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Once you have a replacement air filter in hand, here are your basic steps for removing the old filter and installing the new one: 

  1. Pop the hood or lower the front panel to access your RV’s engine compartment. 
  2. Locate your engine air filter housing. Usually looks like a black plastic box on the top or side of the engine. 
  3. Clean the outside of the filter housing before opening to prevent dust and dirt from falling inside. 
  4. Open the housing and remove the old filter. Depending on the make and model of your RV, you may need a Phillips head screwdriver or a ratchet with a 10-millimeter socket to remove the housing fasteners. 
  5. Remove dirt or debris inside the housing once the filter is removed. Vacuum out as needed. 
  6. Install the new engine air filter with the rubber rim facing up. Make sure it is seated correctly. 
  7. Replace the housing and secure fasteners. 

That’s it! You should be good to go for another year or 12,000 miles, whichever comes first. 

Your motorhome’s engine air filter is an often-overlooked component that must be replaced regularly. Keep it clean, and you’ll have no problem getting your RV anywhere you want.

If you’re still learning the ins and outs of RV maintenance, check out our downloadable RV ownership and maintenance booklet!

When is the last time you checked your motorhome’s engine air filter? Tell us in the comments below.

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