Breathing – Air Intake and Exhaust


Why Clean the Air Filter?

Even in a “clean” marine environment, dust, sand, hair, belt dust and insulation debris can be drawn into an engine’s air intake – and, hopefully, trapped in the air filter. Keeping the air filter clean and in good repair is important to : 1)  prevent contaminants getting inside the engine where they can stick with oil and cause abrasive damage; 2) allow air to flow as easily as possible into the engine with minimal drop in pressure.

5 Types Air Intakes from Marine Diesel Basics

From page 77 Marine Diesel Basics 1

5 Types of Air Intake & Filter


Diesel engines consume huge volumes of air which must flow through the air intake and out through the exhaust. A typical naturally-aspirated 40hp engine draws approximately 136 cubic metres of air per hour (80 cfm) more than twice the volume of a regular shipping container. A turbocharged engine may draw twice this volume of air.

Five designs of air intake/air cleaner are in common use:

  • replaceable paper filter elements (similar to fuel filters)
  • reusable, cleanable rigid filter element
  • washable foam filter around a rigid air intake
  • intake “silencer” – contains no air filter, but dampens air intake noise
  • air intake with no filter or housing – common on older diesel engines (e. g. 1970s)
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