DIY Engine Compression Check: Essential Tips for Diagnosing Engine Health > 자유게시판

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Conducting a standard engine compression test is a straightforward way to evaluate the condition of your engine’s internal mechanics. This test helps you identify whether the piston rings, valves, and head gasket are in good condition. Inconsistent compression across cylinders can reveal underlying issues that might lead to diminished acceleration, vibration, or total engine seizure.

Before you begin, make sure the engine is thermally stabilized. A moderately heated engine gives more accurate results because all parts are thermally expanded to factory specs. Kill the engine and disconnect the key and disconnect the fuel pump relay or fuse to eliminate fuel supply while testing. You should also disable the spark delivery to eliminate risk of sudden startup.

Proceed by taking out each spark plug. Tag every plug to match its cylinder so you can reinstall them correctly later. Use a correctly sized socket and turning tool to safely unscrew them. Avoid letting tools or debris fall into the combustion chambers.

Now, screw the compression gauge into the first spark plug hole. Make sure it is securely fastened to avoid leakage. Have a someone hold the pedal to the floor and engage the ignition for a 6-second interval. Observe the needle rise as pressure increases. Note the highest reading. Repeat this process for each cylinder, making sure to return the dial to zero after each measurement.

After collecting all cylinder measurements, compare them. A well-maintained engine typically has compression between 120 and 170 psi. The readings should be nearly uniform throughout. A gap wider than 15% between the maximum and minimum pressures may indicate a problem. For example, if a particular cylinder lags behind the rest, it could mean a damaged rings, faulty valves, or compromised head gasket.

If you find a low reading, you can do a wet test to help determine the root cause. Insert a minimal quantity of engine oil—approximately 5ml into the affected cylinder via the plug opening. Then repeat the compression test. If the gauge climbs markedly, the problem is likely worn piston rings. Should the value remain unchanged, the issue is probably with the valve seals or cylinder head seal.

When all tests are finished, reinstall the spark plugs, reconnect the ignition and fuel delivery circuits, and run the engine and check for اتوسرویس داوود smooth performance. A compression test doesn’t require high-end gear—a simple gauge and common tools, but it gives you deep understanding of internal engine status. Frequent compression evaluations reduce long-term repair expenses.