On modern vehicles, the PCV system (Positive Crankcase Ventilation System) is essential to ensuring your car or truck is ready to go when you are and remains a long-lasting, reliable vehicle. It’s much more than just emissions control - your PCV system serves multiple purposes and is quite interesting! How does it work, and what are those purposes? Here at Complete Car Care in Flagstaff, AZ, we have those answers for you!
What exactly does it do?
The PCV, or Positive Crankcase Ventilation system, serves quite a few purposes. Primarily, it was developed to reduce emissions - but it doubles as a mechanism to reduce crankcase pressure. The reduction of crankcase pressure was important long before emissions were ever a concern, and the PCV system was a simple way to address both problems efficiently. The PCV system allows for cleaner exhaust, prevents blowby at seals and gaskets, removes crankcase gasses generated by the combustion process that will sludge up and destroy the engine if left unchecked, and allows the engine to run more efficiently thus creating better fuel mileage!
Where does it come from?
The PCV system is not a new feature. When automobiles first became widespread a little over a century ago, when it was accepted that cars and trucks would leak oil. To stop these leaks seals and gaskets were put in place and they did greatly reduce the amount of oil that leaked past but weren’t expected to completely contain the engine oil. Eventually, it was discovered that by using a downdraft tube, case pressure could be ventilated utilizing the airflow generated by the moving vehicle. In order to prevent a vacuum from developing, a separate crankcase breather was also employed - essentially the breather is just an opening that allows fresh air to enter the engine as gasses and pressure are ventilated out. Thus a solution was created, the PCV System.
Interesting Fact:
In WWII, PCV systems were developed to allow engines to run underwater. Tanks couldn’t utilize a downdraft tube, because the engine would fill with water if it were ever submerged. The PCV allowed for a closed system that drew fresh air through the intake breather, into the crankcase breather, and allowed for crankcase pressure to be pulled into the intake, keeping the entire system closed.
In the early 1960s, this technology was applied to automobiles, since it had the added benefit of burning off the gas that would otherwise have been released into the atmosphere. Not only does the PCV system burn off those extra gasses, but it also increases fuel efficiency if the engine is tuned correctly and operating as it should.
Modern engines still utilize this technology, but it’s more important now than ever. Computer systems require correct input to operate correctly, and small oil passages that operate various systems are extremely susceptible to engine sludge.
How does it work?
The system is simple. The PCV valve regulates how much vacuum can pull through the crankcase. It’s hooked into the intake - when the vacuum is high at idle, the PCV valve stops most of that vacuum. As vacuum drops with an increase in RPM, The PCV valve opens, to allow a higher volume of gasses and pressure to be pulled into the intake. As a result, those gasses are recirculated back into the combustion cycle, and burnt off with the fresh fuel and air, preventing those gasses from condensing in the oil, preventing pressure from causing the seals to leak, and preventing pollution from escaping the crankcase.
The breather tube allows fresh air to be pulled into the engine, after the air filter, ensuring debris and moisture aren’t pulled into the engine.
What can go wrong?
Like all automotive systems, the PCV system must be monitored and maintained. If neglected, a faulty PCV system will cause condensation in the oil that leads to blocked passages and damaged bearings, excessive oil consumption, pressure buildup that leads to seal blowouts and oil leaks, and carbon buildup in the intake - any of which could destroy an engine.
How often should a PCV valve be changed?
Now there is no set length of time that you're required to have your car or truck's PCV maintained. It all depends on how you drive and what type of environment your vehicle is put in. Just like all other service schedules, it's ideal to have your valve changed with every major service usually hitting around 30,000 - 90,000 miles. Keeping your vehicle on scheduled maintenance, such as oil changes, fluid checks, and rotations will provide your car or truck with longer life.
Does a Bad PCV Valve Burn Oil?
If you have a bad PCV valve, you are putting your vehicle at risk. The bad valve can create a leak which will cause your car or truck to have excessive oil consumption. The oil consumption will cause the oil to burn which will cause it to smell and will leave a puddle beneath your vehicle. If you notice either of these symptoms, give us a call here at Complete Car Care to schedule service. Any oil leak is a bad leak that we want to check promptly to avoid high repair costs!
PCV components are typically inexpensive, and essential to keep your car, truck, or SUV on the road. They should be maintained regularly, and if any of these symptoms develop, the PCV valve is a good place to start when diagnosing the problem. No matter your repair or maintenance needs, our expert technicians have you covered. For the best auto repair shop in Flagstaff, AZ, call or stop by Complete Car Care today where we treat your car or truck like it is ours!
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