Holset Air Compressors – 012-019   Air Leaks, Compressed Air System

Table of Contents

Initial Check

Initial Check



Wear appropriate eye and face protection when using compressed air. Fly debris and dirt can cause personal injury.

NOTE: The illustrations shown will be of the single-cylinder air compressor. Differences in procedures for SS, QE, and ST model Holset® air compressors will be shown where necessary.

Shut off the engine.

Open the drain cock on the wet tank to release air from the system. Close the drain cock after the pressure is released.


Operate the engine to activate the air compressor.

With the air compressor pumping between 550 to 690 kPa [80 to 100 psi], use a solution of soapy water to check for air leaks in the following areas:

  • Air compressor cover gasket
  • Unloader body o-ring
  • Air compressor head gasket
  • Air compressor valve plate gasket (QE models only)
  • Hose and fitting leaks.

If air leaks are found, replace the leaking gasket or o-ring. Refer to Procedure 012-101, 012-103, 012-104, or 012-106.

Last Modified:  13-Jun-2005