Engine Compression Test: A Step-by-Step Guide > 자유게시판

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Performing a basic engine compression test is a straightforward way to determine the integrity of your engine’s critical moving parts. This test helps you verify if the piston rings, valves, and head gasket are in good condition. Low compression in one or more cylinders can point to mechanical failure that might lead to reduced power, erratic idle, or catastrophic breakdown.

In the initial phase, make sure the engine is slightly heated. A preheated engine gives consistent data because all parts are in their standard running state. Kill the engine and disconnect the key and disable the fuel delivery system to eliminate fuel supply while testing. You should also disable the spark delivery to stop the engine from starting accidentally.

Begin by removing all spark plug units. Note the position of each plug relative to its cylinder so you can reinsert them accurately. Use a specialized spark plug tool and ratchet to carefully take them out. Be careful not to drop any tools into the cylinders.

Insert the gauge into the initial spark plug port. Make sure it is properly seated to obtain reliable data. Have a helper fully depress the accelerator pedal and turn the starter for 5–7 seconds. Track the pressure reading as it peaks. Capture the top pressure number. Apply the procedure to each individual cylinder, making sure to return the dial to zero after each measurement.

When all data is gathered, compare them. A well-maintained engine typically has compression between 120 and 170 psi. The readings should be very similar from one to the next. A discrepancy greater than one-eighth between the highest and lowest readings may indicate a problem. For example, if a single cylinder shows significantly reduced pressure, it could mean a worn piston ring, a leaking valve, or a blown head gasket.

If a cylinder’s reading is abnormally low, you can do a wet compression test to help diagnose the issue. Add a small amount of engine oil—about a teaspoon into the problematic cylinder’s spark plug port. Then repeat the compression test. If the gauge climbs markedly, the problem is likely excessive ring wear. Should the value remain unchanged, the issue is probably with the valve mechanism or head gasket.

Following the evaluation, put the plugs back in, reattach the fuel and spark systems, اتوسرویس داوود and start the engine to make sure everything is working normally. A engine health diagnostic doesn’t require advanced machinery; only a gauge and basic hand tools, but it gives you deep understanding of internal engine status. Periodic testing prevents major failures and lowers maintenance costs.