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.
Cylinder Leakage Test
2021 Ford Edge SE, 4WDSECTION Cylinder Leakage Test
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
- When a cylinder produces a low reading, use of a cylinder leakage tester will be helpful in pinpointing the exact cause.
- The leakage tester is inserted in the spark plug hole, the piston is brought up to TDC on the compression stroke, and compressed air is admitted.
- Once the combustion chamber is pressurized, the leakage tester gauge will read the percentage of leakage. Leakage exceeding 20% is excessive.
- While the air pressure is retained in the cylinder, listen for the hiss of escaping air. A leak at the intake valve will be heard in the TB (throttle body). A leak at the exhaust valve can be heard at the tailpipe. Leakage past the piston rings will be audible at the PCV connection. If air is passing through a blown head gasket to an adjacent cylinder, the noise will be evident at the spark plug hole of the cylinder into which the air is leaking. Cracks in the cylinder block or gasket leakage into the cooling system may be detected by a stream of bubbles in the radiator.
- Install the spark plugs.For additional information, refer to: 2.7L EcoBoost Spark Plugs . For additional information, refer to: 3.3L Duratec-V6 Spark Plugs . For additional information, refer to: 3.5L EcoBoost (BM) Spark Plugs . For additional information, refer to: 3.5L V6 PowerBoost (CN) Spark Plugs . For additional information, refer to: 5.0L 32V Ti-VCT Spark Plugs .
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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.