Compression Check: Testing and Inspection

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

1. Warm engine to normal operating temperature, then turn ignition off.
2. Remove air cleaner and/or intake opening cover.
3. Disconnect injection pump solenoid leads from injection pump.
4. Remove all glow plugs.
5. Install suitable compression gauge into cylinder No. 1 glow plug hole.
6. Crank engine at least five compression strokes with ignition switch off. Record highest reading indicated.
7. Repeat compression check on each cylinder.
8. Compression pressures are considered within specification if the lowest reading cylinder is within 25 percent of the highest.
9. Variations exceeding 25 percent indicate an improperly seated valve or worn/broken piston rings.

CAUTION: Do not add oil to cylinder as this may cause hydrostatic lock.