Symptoms of a Bad PCV Valve (and its Replacement Cost)

(Updated on August 25, 2021)

The PCV, or positive crankcase ventilation, valve allows gas from the engine’s crankcase to get released into the combustion chambers. This helps improve the functionality of the vehicle and increases the efficiency of its engine. But if you have a PCV valve that is bad then you will notice the performance of your car will start to diminish.

Bad PCV Valve Symptoms

The most common symptom of a bad PCV is the overconsumption of oil or a possible oil leak. The reason this happens is because there is more pressure in the crankcase if the PCV valve goes bad. This forces the oil out of the gaskets and seals since there is no other place for the oil to go through. As a result, you’ll see leaky oil underneath your vehicle which means you’ll have to keep putting new oil in your car until you replace the PCV valve.

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Another symptom is a contaminated crankcase vent filter. Oil and hydrocarbons will build up in this filter once the PCV valve goes bad. The water vapor that gets pushed through will end up mixing with the gas. Once that happens, the water buildup will cause you to consume more fuel than normal which will lower your gas mileage. If you know what the crankcase vent filter looks like then you can physically inspect it yourself to see if there is a buildup of contaminants.

Overall, your vehicle’s performance will be very poor as your PCV valve goes bad. All of the pressure built up inside of the engine will eventually cause it to stall on you. Plus, if the PCV valve isn’t closing completely like it should then oxygen will flow into the combustion chamber. This will compromise the normal air and fuel mixture that is necessary to run your vehicle smoothly. Instead, your vehicle will run poorly until it eventually conks out entirely.

PCV Valve Replacement Cost

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Fortunately, replacing a bad PCV valve won’t be too costly for you. The part itself costs about $10 while the labor costs to replace the valve will be about $80 on average. So you should expect to spend about $90 to $100 for a new replacement to your PCV valve. This really isn’t a lot of money when you consider the fact that it will sustain the functionality of your car. If you notice the symptoms of a bad PCV valve and you continue to do nothing about it, then it will ruin the components of your engine which will be even more costly to fix.


2 thoughts on “Symptoms of a Bad PCV Valve (and its Replacement Cost)”

    • Does it sound like marbles in a can? I wonder if the sound you’re describing could be engine knock?

      If you only hear the sound at a specific engine speed even at light engine load, I am inclined to think it is a rattling heat shield though.


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