What Causes Valve Noise?
2 Answers
Valve noise is caused by: 1. Gap formation or severe wear in hydraulic lifters; 2. Too high or too low oil level in the crankcase; 3. Dirty lifters; 4. Worn valve spring seats with grooves, and wear between valve stems and guides; 5. Oil being too thin—replace with oil of appropriate viscosity; 6. Oil pressure being too low or too high. The methods to address valve noise are: 1. Remove the cylinder head; 2. Grind the valves, check the spring tension of the valve springs, and readjust the valve clearance. The function of valves is to specifically input air into the engine and expel exhaust gases after combustion. Based on engine structure, they are divided into: intake valves and exhaust valves.
Last time when I got my car repaired, the mechanic mentioned that valve noise is most commonly caused by improperly adjusted valve clearance. New cars are fine when they leave the factory, but after tens of thousands of kilometers, as metal parts wear out, that 'ticking' sound starts to appear. Additionally, many cars nowadays use hydraulic lifters, which are particularly delicate. If the oil quality is poor or the oil isn't changed regularly, sludge can clog the lifter oil passages, causing noise during operation. Also, if the valve stem and guide wear excessively and become loose, the knocking sound can resemble tapping on a wooden fish. The most troublesome issue is a broken valve spring, which produces a particularly sharp sound. If you encounter such metal knocking sounds, it's crucial to get it checked as soon as possible—the engine is the heart of the car.
