Compression Check: Testing and Inspection

AllData Editors Note - Ford does not provide a cranking pressure specification, only an acceptable range.

The following procedure is to be used when checking compression:

1. Make sure battery is fully charged. Operate the engine until normal operating.temperature is attained. Turn the ignition switch to OFF. Remove air cleaner and or intake opening cover using Intake Manifold Cover T83T-9424-A or equivalent. Disconnect injection pump solenoid leads from injection pump to prevent accidental engine starting. Remove all glow plugs.

2. Install Rotunda Compression Tester 014-00701 or equivalent in No.1 cylinder glow plug hole.

3. Crank the engine (with the ignition switch off) at least five pumping strokes. Record highest reading indicated. Note the approximate number of compression strokes required to obtain the highest reading.

4. Repeat the check on each cylinder, cranking the engine approximately the same number of compression strokes

Compression Test Pressures:

Test Conclusion

Compression pressures are considered normal if the lowest reading cylinder is within 75 percent of the highest. Variations exceeding 75 percent indicate an improperly seated valve or worn or broken piston rings.

CAUTION: Do not add oil to cylinder. This could cause hydrostatic lock.