What are the clearance values for the intake valve and exhaust valve?
2 Answers
The clearance values for the intake valve and exhaust valve are: within the range of 0.20mm to 0.25mm, and between 0.29mm to 0.35mm. If the valve clearance is too small, after the engine operates, the components expand due to heat, pushing the valve open and causing incomplete valve closure, resulting in air leakage, reduced power, severe carbon buildup, or burning of the valve sealing surface. Excessive clearance will accelerate component wear and affect the intake and exhaust conditions of the cylinder. It is essential to adjust according to standard data. The functions of the intake valve and exhaust valve: 1. The intake valve's role is to draw air into the engine to mix with fuel for combustion; 2. The exhaust valve's role is to expel the burned exhaust gases and dissipate heat.
I remember last time there was a rattling noise when driving the car, and after checking at the shop, it turned out the valve clearance was incorrect. The intake valve clearance is usually smaller than the exhaust valve, typically between 0.15 to 0.20 mm for the intake and around 0.20 to 0.25 mm for the exhaust, depending on the vehicle's manual. My old car's exhaust valve clearance was set at 0.23 mm because the exhaust pipe temperature is high, causing greater material expansion, so a larger gap is needed to prevent sticking. When adjusting, a feeler gauge must be used for measurement, and it's best to do it when the engine is cold. Don't attempt to adjust it yourself—I tried DIY once and didn't get it right, resulting in louder noise and increased fuel consumption. In the end, I had to go to the 4S shop to fix it. Regularly checking this clearance is crucial—it prevents premature valve wear and extends engine life, especially after tens of thousands of kilometers when issues are more likely to arise. Developing a habit of checking it once a year can save a lot of money.
