been a well-known fact for many years that a major cause for
excessive engine wear and early failures is the direct result
of poor or no maintenance of intake air systems. The ingestion
of foreign materials in sufficient quantity through a faulty
filter system will in a matter of hours, destroy a 2-cycle or
4-cycle gasoline or diesel engine. To appreciate how this is
possible it must be understood that the air to fuel ratio is
thousands of gallons of air for every gallon of fuel consumed.
While wear is a major consideration,
of equal importance is the loss of fuel economy and horsepower
that can be directly attributed to restricted air filter systems.
There are two basic types of air filter
systems in use -wet and dry. Of the two the dry system, which
uses a replaceable element is most popular and efficient.
Efficiency levels at installation are in excess of 99% for
the dry type and about 96% for the wet type filter.
of the dry type is derived by the use of a specially treated
paper, pleated to increase the area of filtration. Contrary
to popular belief, the dry type filter does not lose its efficiency
when it gets dirty as the build-up of foreign material actually
helps to stop even smaller particles from entering the air flow.
There is, of course, a limit to what is allowable as previously
mentioned, when the air flow is restricted to excess, loss of
horsepower and fuel economy result. Time elements and efficiencies
can best be determined by close adherence to manufacturers recommendations.
The major problem with the
wet type or oil bath cleaners is their inability to stop the
very small particles from entering the air system. As the
air enters the system it travels across the oil bath where
the heavier particles are trapped in the oil. Regular service
intervals are imperative on the oil bath, as build-up of particles
in the bottom of the cleaner will cause a rise in the oil
level and a pullover of oil and contaminants into the air
flow to the engine.
Regardless of which type of unit is
used, the areas in back of the filter are as critical to good
performance as the filter itself. On trucks the location of
the air intake is very critical, that it is not located in
line with exhausts, heavy dust concentration or water spray.
Air leaks of any kind from defective mounting gaskets to cracks
in metal connecting pipes to holes in flexible tubing will
render all but useless the best maintained filter.