Compression Test

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

COMPRESSION GAUGE CHECK
1. Make sure oil in crankcase is of the correct viscosity and at proper level, and battery is properly charged. Operate vehicle until engine is at normal operating temperature. Turn ignition switch to the OFF position, and remove all spark plugs.
2. Install a compression gauge such as Rotunda Compression Tester 303-F011 or equivalent in No.1 cylinder.
3. Install an auxiliary starter switch in starting circuit. With ignition switch in OFF and using auxiliary starter switch, crank engine a minimum of five compression strokes and record highest reading. Note the approximate number of compression strokes required to obtain the highest reading.
4. Repeat test on each cylinder, cranking the engine approximately the same number of compression strokes.





TEST RESULTS
The indicated compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading. Refer to the Compression Pressure Limit Chart.