Compression Test

Note
The compression tester for conventional piston engines reads only the highest pressure of the three combustion chamber in the rotor housing. Use compression tester (49 H075 280) to measure the compression of the three combustion chambers.

Compression Check
1. Check that the battery is fully charged. Recharge it if necessary.
2. Warm up the engine to the normal operating temperature, then stop it.
3. Allow about 10 minutes for the exhaust manifold to cool.
4. Remove the front and rear trailing-side spark plugs.





5. Disconnect the crank angle sensor connector.








6. Connect the SST to the front rotor housing and the battery.





7. Fully depress the accelerator pedal and crank the engine for 5 to 10 seconds.
8. Record the compression of the three combustion chambers and cranking speed.

Compression:
589 kPa (6.0 kgf/cm2, 85 psi)-250 rpm.
Differential limit between chambers:
147 kPa (1.5 kgf/cm2, 21 psi)-250 rpm.

9. Check the rear chambers by using the same procedure.
10. Compensate the compression values if they are measured at cranking speeds other than standard or if they are measured at high altitude.





Cranking speed compensation
Compensate the compression according to the cranking speed.





Altitude compensation
Compensate the compression according to the altitude.