Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Compression Test
2021 Ford Edge SE, 4WDSECTION Compression Test
WARNING: This page is about a different car, the 2020 Ford F-150. 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.
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NOTE: Failure to remove all fuel injectors may result in inconsistent test results.
Remove the fuel injectors. REFER to: Fuel Injectors LH . and the REFER to: Fuel Injectors RH .
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.NOTE: Use a fuel injector hold down from a fuel injector that has been removed for the Compression Test Adapter.
- Install the Compression Tester Adapter (303-1682) 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, and using the auxiliary starter switch, crank the engine a minimum of 5 compression strokes and record the highest reading.
- Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
- There must not 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 Tester Adapter (303-1682) and the commercially available diesel compression tester.
- Disconnect the battery charger from the battery.
- Install the fuel injectors. REFER to: Fuel Injectors LH . and the REFER to: Fuel Injectors RH .
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.