What Situations Will Occur When a Car's Exhaust Valve Fails?
2 Answers
When a car's exhaust valve fails, the following situations may occur: 1. Engine Idling: After the exhaust valve is damaged, it will be unable to control the amount of exhaust gas recirculation. Excessive exhaust gas participating in recirculation will affect the mixture concentration, leading to difficulties in starting, engine shaking, unstable idling, and weak acceleration, all of which can impact the engine's performance. 2. Burning Oil and Blue Smoke: A damaged exhaust valve can cause the car to burn oil, resulting in blue smoke from the exhaust pipe. The exhaust valve functions to separate oil and gas; when working properly, it only draws in exhaust gas and not oil. However, if the exhaust valve is damaged, it loses its oil-gas separation function. While drawing in air, it may also suck in oil, allowing oil to enter the combustion chamber, leading to oil burning and blue smoke emissions.
I've been driving this old car for several years. Last time when the PCV valve failed, the car shook like dancing at idle, obviously the engine was unstable. After parking and checking the engine oil, I saw oil stains on the ground - excessive crankcase pressure caused oil leakage. This situation is quite common, especially after long-distance driving. When the valve gets clogged or aged, pressure builds up easily leading to oil leaks and sudden increase in oil consumption. The mechanic said if not handled promptly, it might damage the seals, and repair costs would skyrocket. I remember once breaking down halfway during a vacation - turned out the PCV valve failed, with blue smoke from exhaust indicating severe pollution, had to call a tow truck. Since then, I always ask them to check the PCV valve during regular maintenance to ensure it's clean and unobstructed, avoiding future troubles and driving with more peace of mind.