Compression Inspection

1. Install the SST (49 F018 901)  to the trailing or leading side plug hole of the rotor housing.
   Fig 1: Measuring Compression Pressure Using SST

   Courtesy of MAZDA MOTORS CORP.
2. Set the SST (49 F018 9A0B)  as shown in the figure.
   • When using the WDS or equivalent, set the WDS or equivalent to the SST (49 F018 901, 49 F018 904)  as shown in the figure.
3. Depress the accelerator pedal fully and crank for 5-10 s. 
4. Read the compression and engine speed.
   Fig 2: [Setting SST Equivalent]

   Courtesy of MAZDA MOTORS CORP.

   Compression pressure 

   • Standard: 830 kPa {8.5 kgf.cm ²  , 120 psi} [250 RPM] 
   • Minimum: 680 kPa {6.9 kgf.cm ²  , 98.6 psi} [250 RPM] 
   • Standard difference in chambers: 

     Within 150 kPa {1.5 kgf.cm ²  , 21.8psi} 

   • Standard difference in rotors: Within 100 kPa {1.0 kgf.cm ²  , 14.5 psi} 
5. Perform the same procedure for the other rotor housing.
6. If the compression is at the minimum or less, or the difference in the chambers and difference in the rotors exceed the specifications, replace or overhaul.

A: Standard compression pressure

B: Minimum compression pressure