Cylinder Compression Test

Conducting a Cylinder Compression Test. Before conducting a compression test, disable the ignition and the fuel injection system if the engine is so equipped. Prop the throttle plate into a wide open position to allow an unrestricted amount of air to enter the cylinders during the test. Remove all of the engine's spark plugs.

Connect a remote starter button to the starter system. There are may types of compression gauges available. The screw in type tends to be the most accurate and easiest to use. Carefully install the gauge into the spark hole of the first cylinder.

Connect a battery charger to the car to allow the engine to crank at consistent and normal speeds needed for accurate test result. Depress the remote starter button and observe the gauge's reading after the first engine revolution. Allow the engine to turn through four revolutions and observe the reading after the fourth. he pressure from The reading should increase with each revolution. Readings observed should be recorded. Before removing the gauge from the cylinder, you can release the pressure from it using the valve on the gauge.

After testing all the cylinders. If one or more cylinders is much lower than the other, continue nder with testing those cylinder with the test. Squirt a small amount of oilring sealing into weak cylinder. Reinstall the compression gauge into that cylinder and conduct the test. If the reading increases with the presence of oil in the cylinder, the most likely cause of the original low readings was poor piston sealing. Using oil during a compression test is normally referred to as a wet test.

Four Stroke Cycle

Four Stroke Cycle has the following parts air and fuel, intake valve, spark plug, exhaust valve, combustion chamber, piston and crankshaft.

Four Stroke Cycle has four stroke mainly intake stroke, compression stroke, power stroke and exhaust stroke.

Intake stroke is when piston move downward from top dead center to bottom dead center producing a suction force to draw air and fuel mixer to inter in cylinder from carburetor. The intake  valve is open allowing mixture of fuel get into cylinder. The exhaust valve is close to let only mixture get in.

Compression stroke is when the piston moves upward from bottom dead center to top dead center pushing the air and fuel mixture to get into a small space to prepare for combustion. The intake and exhaust valves are both close to ensure that no mixture of fuel escape from cylinder. At the end of this stroke, the spark plug delivers spark to ignite the fuel mixture until compression ends. In diesel engine, purely air is compressed to raise temperature and diesel fuel is injected at end of the stroke.

Power stroke is when the piston moves downward from top dead center to bottom dead center cause by the pressure produce by combustion or burning of fuel mixture. This is the source of power of an engine. The intake and exhaust valve are both close that no power can escape from the cylinder. Leakage of power during this stroke result to a low performance engine or lack of power.

Exhaust stroke when the piston moves upward from bottom dead center to top dead center pushing the burned gasses to get out of the cylinder. The intake valve is close and exhaust valve is open making a away for the exhaust gas to get out. At exactly end of this stroke, exhaust valve closes.