As the engine mileage increases, the compression in its cylinders decreases. If the wear limit is reached, the engine must be replaced or repaired. The permissible pressure difference in the individual cylinders must not exceed 2.0 bar (2.0 atm). A large pressure difference indicates a valve defect, cylinder or piston wear.
Engine | Compression | |
New engine | wear limit | |
1200 cc/34 hp | 7.0-9.0 bar (atm) | 6.0 bar (atm) |
1300 cc/44 hp | 7.5-9.5 bar (atm) | 6.5 bar (atm) |
1600 cc/50 hp | 8.0-10.0 bar (atm) | 7.0 bar (atm) |
Adjust valve clearance before checking compression.
To perform the test, the engine must be warmed up to operating temperature. Unscrew all spark plugs, connect the compression tester according to its instruction manual.
Instruct an assistant to fully depress the accelerator pedal; it must be pressed during the entire test procedure.
Operate the starter for approximately 5 seconds. Determine the amount of compression in this cylinder.
Check all other cylinders one by one and compare the values obtained with the nominal values.
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