How Oil Bath Air Breather Works

An air breather, or better known as an air cleaner, is a device usually mounted to the top of an engine and is designed to provide clean, filtered air to the vehicle's intake system. The air cleaners in most modern vehicles use a dry paper cartridge that must be changed periodically. Oil bath air cleaners were used primarily on early trucks and cars, but for the most part were phased out in the 1960s. Today, oil bath air cleaners are used mainly in large farm tractors where extremely dusty conditions may exist.

The oil bath air cleaner consists of a reservoir (or cup) that holds the oil. The reservoir is located at the bottom of the air cleaner. The body of the air filter rests on the reservoir and is clamped or screwed down. The air filter can be mounted and attached directly to the top of the carburetor, or it can be mounted remotely and connected to the carburetor via hoses or tubing.

Air coming into the oil bath air cleaner's inlet is forced vertically down toward the oil reservoir. Once the air reaches the oil reservoir at the bottom, it changes direction rapidly and is then forced back up to the engine's intake system. It is the rapid change of direction in the air mass that cleans the air--while the air has no problem making such an abrupt change in direction, the sluggish dirt particles carried in it cannot change direction as quickly and end up being trapped in the oil reservoir.

Accumulation of dirt, condensation and water from driving through rainy conditions will cause the oil level in the reservoir to rise. This necessitates regular servicing of the air cleaner to keep your engine running efficiently. In normal driving conditions the service interval may be 2,000 to 3,000 miles. But in extremely dusty conditions, an oil bath air cleaner may require servicing as regularly as once a day.

The air cleaner will need to be disassembled for servicing by removing it from the engine. Dirt and sludge is normally cleaned out of the cup with a solvent such as kerosene. To complete the servicing, the cup is replenished with fresh oil and then the air cleaner is reassembled.