What is the troubleshooting method for low cylinder pressure?
2 Answers
The troubleshooting method is as follows: if the pressure in all cylinders is generally lower than the specified value, it may be due to valve leakage in all cylinders, cylinder wear, excessive piston-to-cylinder clearance, piston ring wear, or other sealing issues; if the pressure in an individual cylinder is too low, it may be caused by valve erosion in that cylinder or cylinder gasket erosion damage leading to leakage. The main reasons for low cylinder pressure are the following three points: 1. Excessive piston ring side clearance and end gap: Excessive piston ring side clearance and end gap, shortened gas passage, or wear of the first sealing surface of the piston ring, resulting in poor sealing; 2. Excessive wear between the piston and cylinder: Excessive wear between the piston and cylinder increases the piston-to-cylinder clearance, causing the piston to wobble during movement in the cylinder, affecting the proper sealing between the piston ring and the cylinder; 3. Piston ring sticking or carbon buildup: Piston rings stuck in the ring groove due to sticking or carbon buildup prevent the ring's natural elasticity from functioning, losing the first sealing surface between the compression ring and the cylinder wall.
I've always enjoyed tinkering with cars and have encountered low cylinder pressure several times. Simply put, first buy a compression tester and measure the pressure of each cylinder one by one. If it's below the standard, you need to investigate the cause. Common issues include worn piston rings causing air leakage—you can remove the spark plug and inject a bit of engine oil to test. If the pressure rises, it indicates a piston ring problem. Another common issue is valve leakage—start the engine and listen for a hissing sound, or remove the cylinder head to check the valve seats. Cylinder wall wear is also possible—feel the inner wall for scratches. Additionally, don’t forget to check if the cylinder gasket is leaking or if there are gaps in the intake manifold. For regular maintenance, remember to change the engine oil and air filter periodically to reduce wear. After troubleshooting, restoring normal pressure can improve engine efficiency and fuel economy. In short, take it step by step, safety first. If you can’t handle it yourself, seek help from a professional mechanic.
