Test Results

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

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.

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If one or more cylinders reads low, squirt approximately one tablespoon of clean engine oil Super Premium Motor Oil SAE 1OW30 XO-1OW30-QSP meeting Ford specification WSS-M2C153-G on top of the piston(s) in the low-reading cylinder(s). Repeat the compression pressure check on these cylinders.

Interpreting Compression Readings
1. If compression improves considerably, piston rings require service.
2. If compression does not improve, valves are sticking or seating improperly.
3. If two adjacent cylinders indicate low compression pressures and squirting oil on piston does not increase compression, the head gasket may be leaking between cylinders. Engine oil and/or coolant in the cylinders could result from this condition. Use the Compression Pressure Limit Chart when comparing cylinder compression readings to determine if the lowest reading is within 75 percent of the highest reading.