Nobody wants their car to break down. To keep your vehicle running well, you need to provide it with regular service. Have the oil changed a few times per year, rotate the tires, and check and replace the brakes as needed. A good auto care service will take care of all these maintenance tasks for you. However, you may still want to know more about the processes they follow, when service is needed, and what other types of services may help your car last longer. We've build this website for people like you — responsible car owners who just want to learn more. Enjoy!
How much do you know about your car's positive crankcase ventilation (PCV) system? If you're staring at your screen blankly right now, then don't worry. It's likely that most drivers aren't familiar with this part. Your car's PCV system is a part of its emission control equipment, and it serves a crucial role in helping your engine run cleanly and efficiently.
The PCV system's primary purpose is to catch gas, oil, and air that escapes the combustion chamber. These rogue elements are known as blowby, and they can harm your car's operation if they make their way back into the air intake. Likewise, blowby gases can be harmful to the environment if allowed to escape into the air.
How a Bad PCV Valve Affects Your Engine
Although your PCV valve is technically a part of your car's emissions system, it still significantly affects your engine's operation. Modern engine design means that blowby gases no longer have an escape route without the PCV system, so a failed valve can push them back into the intake. This excess air and gas can result in an imbalance in your engine's fuel-to-air ratio.
Failed PCV valves can also push oil where it doesn't belong since small amounts of oil sometimes enter the blowby gases. Depending on the failure mode, this can cause relatively benign problems such as a build-up of oil around your air filter. Unfortunately, a valve that's stuck close can also cause an increase in crankcase pressure, which has the potential to result in more severe damage.
Recognizing the Signs of Failure
A failing PCV valve can cause driveability issues, but they are not always easy to pin down to this specific part. The blowby gases' composition will not necessarily be uniform, potentially causing a lean (too much air) or rich (too much fuel) condition. In either case, your car will eventually trigger a check engine code, and you may notice poor idling, rough acceleration, or reduced fuel economy.
In some cars, you may also notice a loss of oil without any apparent leak. When a clogged or stuck PCV increases crankcase pressure, it can force oil past seals elsewhere in the engine. You will rarely lose much oil this way, but it may be enough to require occasional top-ups between oil changes.
Unfortunately, most cars won't have a specific error code to indicate a PCV system problem. For this reason, it's usually best to have an experienced mechanic diagnose any codes that point towards fuel mixture issues or oil loss. Fortunately, PCV valves tend to be relatively cheap and easy to replace once a mechanic has identified the problem.
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22 October 2020