How to Solve Engine Piston Slap?
2 Answers
Engine piston slap can be resolved by the following methods: 1. If knocking sounds occur in low-temperature environments after starting the car and disappear as the temperature rises, this type of piston slap can be temporarily ignored, and driving can continue; 2. If the knocking sounds persist or become more pronounced after the engine reaches normal operating temperature, the driver should avoid high-speed driving, stop to inspect promptly, and prevent potential traffic accidents; 3. If severe cylinder ovality, scoring, or excessive clearance between the piston and cylinder is found after removing the cylinder head and extracting the piston, replacement is necessary—replace the cylinder liner, piston, and piston rings; 4. If connecting rod deformation is detected, replacement is strongly recommended.
Engine knocking is no trivial matter and must be addressed promptly. I dread hearing that metallic tapping sound, which is usually caused by excessive clearance between the piston and cylinder wall. It's most noticeable during cold starts, right? Don't rush to dismantle the engine just yet—check these three things first: Has the engine oil been left unchanged for too long and become too thin? Low-quality oil can't form a proper oil film. Are the spark plugs the wrong model? Incorrect heat range can easily cause detonation. For older vehicles, check the wear on the crankshaft bearings—excessive clearance can lead to insufficient oil pressure. If the knocking persists even after the engine has warmed up, head to the repair shop immediately and use a borescope to inspect the cylinder walls for scratches. If the wear is severe, you'll need to bore the cylinders and replace the piston ring set.
