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Different Precleaner


A precleaner is a better, more effective way to extend air filter life. There are three types currently available. These are the collector (dust) bowl, aspirated, and atmosphere discharge types. All operate on the principle of centrifugal force. The method of dirt removal for each type of precleaner will be reviewed in detail as follows:



This precleaner is a clear plastic, collection bowl type; it is sometimes referred to as a dust bowl precleaner. Air is drawn up through the bottom, over angled vanes, causing the air to spin. The dirt follows the inner wall up and over the edge into the collection bowl while the clean air enters the intake pipe.

Problems can include:

  • The need for frequent cleaning of the collection cup, especially when moisture turns the dirt into mud.
  • The collection bowl becomes cracked, scratched, and cloudy over time, making visual inspection nearly impossible.
  • The unit must only be mounted vertically.
  • Some of the dirt from the collection cup can be drawn down into the filter element when the engine is throttled down or shut off.
  • This precleaner is only efficient within a limited range of particle sizes.


The aspirated style precleaner consists of two major sections, the precleaner and venturi.

The precleaner section centrifugally separates contaminate which is directed to a low-pressure area. The venturi section located in or on the exhaust. This creates a vacuum to carry away contaminates which are then discharged into the atmosphere.

This is a fairly efficient type of precleaner when it is new, but in time some significant problems can be encountered, including:

  • Moisture mixing with the dirt clogs the ports or vacuum tubing.
  • Fresh air carried over into the exhaust stack via the vacuum tubing can cause re-ignition of unspent fuel, causing a rapid “burn out” situation in the muffler or exhaust stack.
  • Restriction caused by the venturi can create backpressure resulting in an engine running hotter and less efficiently.



Incoming air is drawn in past louvered openings, which rotate the internal, free spinning impeller. The centrifugal force caused by the spinning impeller separates the dirt, dust, moisture, and other particulate from the air. The cleaned air then enters the intake stack while the dirt is expelled, through a louver, back into the atmosphere.

Problems can include:

  • The need to vertically mount bottom discharge units to achieve efficient discharge of dirt and moisture.
  • Cracking or shattering of plastic units or components.
  • Rusting and corrosion of carbon steel constructed units.

Precleaners cannot completely eliminate air filters; they do however vastly extend filter life. Also precleaner use can help with lower fuel consumption, reduced maintenance and extended time between overhauls.

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