What are the symptoms of a faulty crankcase ventilation valve?
3 Answers
Crankcase ventilation valve failure can lead to the following symptoms: 1. It can cause an increase in pressure within the crankcase and contaminate the engine oil inside. When the engine is running, the combustion of the air-fuel mixture pushes the piston downward, allowing some gases to enter the crankcase through the piston rings. When there is an excessive amount of gas in the crankcase, the pressure inside increases, making it more difficult for the piston to move downward. 2. When the crankcase one-way valve is damaged, severe oil leakage may occur from the oil pan gasket. The crankcase ventilation system includes a one-way valve; if this valve is damaged, it can cause excessive pressure inside the crankcase, potentially leading to oil seepage from some gaskets.
That time when I was speeding down the highway in my vintage car, the engine suddenly started jerking like it had hiccups. Even after stopping, the idle was unstable and the oil light on the dashboard came on. I thought it was an ignition system issue, but upon checking the oil, I found it was depleting rapidly with minor leaks. My mechanic friend diagnosed it as a failed crankcase ventilation valve. This component is supposed to vent crankcase gases to prevent pressure overload—once clogged or malfunctioning, it can cause oil to leak into the combustion chamber, increasing fuel consumption and emitting blue smoke. I ended up replacing the valve and cleaning the carbon buildup in the fuel system. Now the car runs as smooth as silk. A reminder to fellow car enthusiasts: regularly check the valve's functionality to avoid engine damage, especially in older models prone to this issue.
My new SUV has only been driven for half a year, but I already feel a significant increase in fuel consumption. For daily city commuting, it burns nearly one liter more fuel compared to my friend's identical model. The engine shakes noticeably, especially when decelerating. During my own troubleshooting, I noticed some blue smoke from the exhaust. After checking online, I suspected the crankcase ventilation valve might be the culprit—it's responsible for maintaining crankcase pressure balance. If it gets stuck or leaks, abnormal pressure can cause the engine oil to burn faster and increase emissions. I tried manually testing if the valve flap moved freely, and just by touching it, I knew something was wrong. I quickly replaced it with an aftermarket part, and the power returned to normal. I also learned a lesson to regularly maintain this small component—it saves both money and hassle.
