Cylinder compression test

GENERAL INFORMATION
If a cylinder is suspected of low compression, check the compression of the individual cylinders with a compression gauge. On a diesel engine this is more difficult, as an adapter that screws in place of the glow plugs is required. This determines which pistons, valves or piston rings do not hold pressure. If the engine is still relatively new, compression should be approximately 32.0 bar. The wear limit is 20.0 bar. If compression is below this value, decide whether to replace or repair the engine. It is also important whether one or all cylinders have poor compression. If, for example, the difference between individual cylinders is 5.0 atm, the "bad" cylinder may have stuck valves, and only cylinder head repair, i.e. valve repair, may be required. It is also possible that the piston rings have seized in their grooves, causing pressure to leak past the piston into the crankcase. If compression loss is the same in all cylinders, in most cases cylinder wear can be assumed. To check compression, warm the engine to operating temperature and remove the glow plugs. Disconnect the wire from the fuel shut-off solenoid valve. Connect the compression tester in accordance with the manufacturer's operating instructions. An assistant should sit in the vehicle and crank the engine for approximately 5 seconds while fully depressing the accelerator pedal. Check the compression in each cylinder in turn and compare with the specified value. If compression is low in one cylinder, a temporary sealing product can be poured into the spark plug hole as first aid. Information on these products is available from auto parts dealers.