How Do You Test Engine Block Compression?
When the gasoline explodes in a cylinder and moves the piston, worn rings or valves or a bad head gasket allows part of the energy of the explosion to escape, causing a loss of power and poor fuel economy. This means bad compression. You can check the compression of an engine yourself with a compression gauge. Ask a friend to help you, because you must engage the starter while working under the hood. Remove all the spark plug wires and then remove all the spark plugs form the engine. Be careful not to allow dirt to fall into the spark plug holes. Disable the ignition by pulling the main coil wire from the distributor or the fuse or main ground wire from an electronic ignition. Insert the input hose from the compression gauge into one of the spark plug holes and tighten it with the wrench. Have your friend engage the starter and crank the engine for about five seconds. Note the reading on the compression gauge and write it down. Typically the reading should be about 140 to 160 psi (poun
