Mechanical Inspection: Compression
WARNING: This page does not describe the selected car, but rather 15 other vehicles, including the 2000 Mercury Villager, 2000 Mercury Mountaineer, 2000 Lincoln Navigator, 2000 Ford Windstar, and 2000 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
Check engine compression with engine at normal operating temperature, all spark plugs removed (on dual plugs, remove exhaust side only), and throttle wide open. Ensure crankcase is full and oil is of correct viscosity. With compression gauge installed, use remote starter switch to crank engine. Crank engine at least 5 revolutions, and record highest reading. Repeat procedure for all cylinders, using approximately same number of revolutions. Lowest compression reading should not be less than 75 percent of highest compression reading. No cylinder compression reading should be less than 100 psi (7 kg/cm2 ).
WARNING:
Because fuel injectors on many models are triggered by the ignition switch, DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine to prevent fire hazard or engine oiling system contamination.