Compression Test
WARNING: This page is about a different car, the 2019 Ford F-550 Super Duty, 2019 Ford F-450 Super Duty, 2019 Ford F-350 Super Duty, and 2019 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
- Make sure the oil in the crankcase is of the correct viscosity and at the correct level.
- Operate the engine until it is at normal operating temperature. Turn the ignition switch to the OFF position.
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NOTE: Failure to remove all glow plugs may result in inconsistent test results.
Remove the glow plugs. REFER to: Glow Plugs .
NOTE: The battery charger must be left connected during the compression test and disconnected when the test is complete. - Connect a battery charger to the battery.
- Install the Compression Test Adapter (303-1515) and a commercially available diesel compression tester.NOTE: Note the approximate number of compression strokes necessary to obtain the highest reading.
- Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position, crank the engine a consistent number of strokes (minimum of 2 compression strokes to 12 compression strokes). Record the readings.
- Repeat the test on each cylinder, cranking the engine the same number of compression strokes, record the readings. Compare the readings of the 8 cylinders.
- There must be a minimum cylinder pressure of 2068.4 kpa (300 psi) and have no more than a 20% difference from the average on any given cylinder.
- Investigate and repair any cylinder(s) that are outside the 20% range.
- Remove the Compression Test Adapter (303-1515) and the commercially available diesel compression tester.
- Disconnect the battery charger from the battery.
- Install the glow plugs. REFER to: Glow Plugs .