Checking the compression in the cylinders (Mondeo 2)

Compression testing is one of the most important diagnostic operations. The compression value and its change after several strokes, as well as the difference in values for individual cylinders, can be used to determine the technical condition of the engine cylinder-piston group and its valve mechanism with a high degree of accuracy without disassembling. Pre-warm the engine to operating temperature.

To check the compression, you need to do the following:

- unscrew the spark plugs with a spark plug wrench (subsequent work must be carried out taking into account the model of the installed engine);

- open the throttle valve fully;

- install the compression pressure sensor into the first spark plug hole;

- ask an assistant to turn on the starter;

- turn the engine crankshaft until the arrow shows maximum pressure;

- check the remaining cylinders in turn in the same way.

A decrease in pressure (about 20%) in one of the cylinders, accompanied by engine vibration at idle, may be due to increased wear of the camshaft cams. Low and uneven compression may be caused by wear of the piston rings, which can also be detected by excessive oil consumption by the engine. See the appendix for normal compression values for a new engine.