Mechanical Inspection: Compression
WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 1999 Mercury Tracer, 1999 Mercury Sable, 1999 Mercury Mystique, 1999 Mercury Grand Marquis, and 1999 Mercury Cougar. However, it is still accessible from the selected car via links, so may be relevant.
Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. Compression pressures are considered within specification if the lowest reading cylinder is within 75 percent of the highest reading cylinder.
WARNING:
DO NOT use ignition switch to crank engine during compression tests. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system.