What is the appropriate valve clearance?
2 Answers
Valve clearance is appropriate at 0.25mm to 0.35mm. When the engine is running, the valves will expand due to temperature increase. If there is no gap or too small a gap between the valve and its transmission components in the cold state, the thermal expansion of the valve and its transmission components in the hot state will inevitably cause the valve to close improperly, resulting in air leakage during the compression and power strokes of the engine, which reduces power output. In severe cases, it may even make the engine difficult to start. Valve clearance refers to the gap between the tail end of the valve stem and the components of the valve transmission group when the valve is completely closed. The valve clearance is determined by the manufacturer during design and testing, with each engine having its own standard. Simply adjust it according to the standard.
Having driven for so many years, I know valve clearance is quite crucial. The proper valve clearance typically ranges between 0.2 to 0.5 millimeters, depending on your engine type and vehicle model. For my old sedan, the manual specifies about 0.25 mm on the intake side and 0.35 mm on the exhaust side. Why adjust it properly? Too small a gap can cause the valves to seize when the engine heats up, leading to power loss; too large a gap results in annoying clicking noises, wasting fuel. I don’t dare to mess with it myself—every time I service the car, I take it to the repair shop where they use professional feeler gauges for accurate measurements. Regular checks help extend engine life, saving both hassle and money. Also, slight noise during cold starts is normal—don’t panic. In short, always refer to the manufacturer’s specs instead of guessing to avoid costly and time-consuming overhauls.
