Whether The Filter Element Needs Replacement & Differences Between Filter Elements of Different Prices, Plus Identification Methods

Is it acceptable to take down a dirty filter element, blow it with a high-pressure air gun, and reinstall it if we don’t replace it?Many repair shops claim this works for dirty filter elements, but it’s actually not feasible. Here are two reasons:

First, the filter cartridges used in family cars are generally made of paper. The 5-micron gaps are fiber grids formed by interweaving wood pulp fibers—note that it’s wood pulp fiber. Blowing with a high-pressure air gun can indeed remove most surface particulate dust, but it also has a high probability of breaking the grids of wood pulp fibers, reducing the filtering capacity. The 5-micron gaps may be expanded to 50 microns; this damage isn’t visible on the surface, but the internal grids are severely damaged, causing the element to lose its ability to filter air.

Second, the internal gaps of these grids are already filled with many tiny particles, which are invisible to the naked eye. While surface dust is blown away, the particles embedded inside the grids can’t be removed and will remain there, blocking the engine’s air intake.

These two reasons explain why paper cartridge filters can only be replaced, not cleaned by blowing.

What Are the Differences Between Air Filter Elements of Different Prices, and How to Identify Them?

Although common dry paper air filter elements are all paper-based, their materials and manufacturing processes vary. High-quality air filter elements are made of wood pulp mixed with synthetic fibers, bonded with glue. They are relatively rigid and won’t deform easily when damp.

In contrast, low-quality air filter cartridges use recycled pulp mixed with starch and talcum powder, also bonded with glue. They are soft in texture. These aren’t counterfeit products—they meet basic testing standards at low costs and can initially satisfy the engine’s filtering needs. However, they have a critical flaw: they can’t withstand moisture. Once damp, the starch and talcum powder inside will become sticky, destroying the original uniform 5-micron gaps. Some gaps may widen to 50 microns, while others may be completely blocked. Additionally, the filter elements are prone to deformation and collapse, which not only obstructs air intake but also renders them ineffective for filtration. Worse still, the starch and talcum powder can be sucked into the engine, causing more carbon deposits. These issues don’t occur with high-quality air filter elementsmade of wood pulp and synthetic fibers.

Identification Method for Air Filter Cartridges of Different Prices

Apply iodine tincture (which is yellow) to the filter element. Iodine doesn’t react with wood pulp or fibers—if the applied area remains yellow, it’s a high-quality air filter element. If the area turns black, it indicates the presence of starch, meaning it’s a low-quality one.

Besides this dry paper type, there are also non-woven filter elements, foam filter elements, cotton fiber filter elements, etc.