What sound does a faulty exhaust valve make?
3 Answers
Exhaust valve failure will produce a whistling sound. When the exhaust valve is damaged, it cannot control the amount of exhaust gas recirculation. Excessive exhaust gas participating in recirculation will affect the concentration of the air-fuel mixture, and the car may experience difficulties in starting, engine shaking, unstable idle speed, and weak acceleration, affecting engine performance. The following is relevant information about the car exhaust valve: 1. Function: The car exhaust valve allows exhaust gas to re-enter the cylinder for combustion. This small amount of exhaust gas reduces the temperature in the cylinder during combustion. Since nitrogen oxides are generated under high-temperature and oxygen-rich conditions, this inhibits the formation of nitrogen oxides, thereby reducing the NOX content in the exhaust gas. 2. Causes of damage: Quality issues with the exhaust valve itself; improper maintenance; fuel quality problems; the exhaust valve operates at high engine temperatures, and over time, it will age like the valve cover gasket and rubber rings.
The most common sound of a faulty PCV valve is a hissing air leak noise, resembling a pressure cooker with a gap, most noticeable at idle. The sound may lessen when accelerating, but engine vibration worsens. Having run an auto repair shop for years, I've seen many such cases—stuck valves or aging seals often cause this issue, typically near the engine's intake. Beyond the annoying noise, it can lead to weak acceleration, surging fuel consumption, and emission light activation. Ignoring it long-term may clog the catalytic converter, costing more to fix. If you hear persistent hissing, don't push your luck—grab a flashlight to check for valve-area vibrations or heat. Replace valve seals promptly, and prevent buildup with regular carbon cleaning.
My car had a problem with the exhaust valve before. When starting, I could hear a hissing sound from the engine, like a tire slowly leaking air. The noise was especially loud when idling, and it became lighter when accelerating, but the car felt sluggish and jerky. The mechanic at the shop checked it and said the valve core was completely clogged and not sealing properly. After replacing it with a new one, the noise disappeared. This issue is common in older cars—carbon buildup can jam the valve, not only causing annoying noise but also leading to excessive emissions and even triggering the engine warning light. I recommend that car owners note when and under what conditions the noise appears, such as being more noticeable after a cold start or after highway driving, to help with diagnosis and avoid delaying until a major engine overhaul is needed.
