How much oil can a bad PCV valve burn? Here is the answer

Is your car burning more fuel than normal? This can result from a myriad of factors, one being a defective positive crankcase ventilation valve.

If you have a bad PCV valve, the gaskets and seal will burst and result in oil leaks. The engine will consume more oil as it compensates for the leaking proportion. The lost oil might constitute around 10% of the total amount consumed.

To understand the complex nature of this system, we need to outline its working principles.

An engine runs on the energy generated from the fuel it consumes. The fuel is made to explode and the engine harvests the energy. The explosions however create vapors that sometimes escape into the crankcase. This is the lower part of the engine and the place the engine oil stays.

The vapors are usually made up of among other things, unburnt fuel. If they are left to stay in the crankcase with the engine oil, they will contaminate it. The oil will turn into sludge in no time.

Sludge is the last thing you want in your engine. It causes clogs and unexpected failures. The building pressure would also be too much for the system to bear, there needs to be a vent to release the excess gases. If not, the seals and gaskets could blow up.

Before PVC valves, engines used to let the extra fumes out through a hose directly from the system into the environment.

The dangerous emissions however caught the attention of the federal government which made it law for all gasoline engines to have special one-way valves to contain the harmful emissions. Diesel engines were not so much affected by this order.

The PVC valve collects and redirects the crankcase gases back into the air intake system. This is where the gasses are burned again to reduce their effects on the environment. More fresh air is fed to the system via a breather tube.

The tube is rarely talked about but its importance in the smooth running of the process cannot be ignored. As the air circulates, it rids the crankcase of moisture and combustion waste. This way there is no sludge build-up in the system. 

This process goes a long way in maintaining the engine’s condition and extending oil life. Like any other car part, the PVC valve is not immune to failure. It might get clogged and unable to pass the excess gas out.

If this happens, your car will experience oil leaks which will cause excessive oil consumption. The intake system might also get affected. If you experience surging and oil leaks, check the PVC valve first.

Manufacturers try to estimate a PVC valve’s lifespan but car aging is subjective. They might put the mark on 33000 km to 81000 km or 20500 miles to 50300 miles, but things can get messy way earlier than this. The user’s manuals do not offer any recommendations, no wonder car owners never take time to read them.

The good thing about PVC valve malfunctions is that they can be identified by mere visual inspection. You don’t need a mechanic to tell you when your PVC valve is clogged. You might not be able to do the repairs yourself but they are quick and pretty affordable.

To prolong your PVC valve’s lifespan you might want to consider changing your oil more often. Delayed oil changes result in gum build-ups which negate the valve’s efficiency.

Is The PVC valve Important?

It might not be obvious to new car owners but if a bad PVC valve is not replaced, it can result in more engine damage than you can imagine. You might have to replace the entire system if the damage is extensive.

The effects do not end with the common oil leaks and high fuel consumption issues, the engine might suffer the blunt as well. These problems are easy to detect but this does not mean the effects are in any way mitigated, dirty engine oil will not spare the engine even if detected.

Most car owners realize their PVC valves need replacement when it’s too late. This is because of the lack of awareness of the importance of regularly inspecting your PVC system. Some of the damages that can result from a faulty PVC valve are expensive.

Another class of car owners who ignore their mechanics calls for PVC valve replacement. Some car manufacturers recommend when a car’s PVC valve should be replaced but the car owners for some reason ignore these recommendations.

Signs That Your PVC Valve Needs Replacement

When the PVC valve clogs or malfunctions in any way, you will notice these signs.

  • Increased Internal Engine Pressure. The valve’s role is to release the extra pressure from the crankcase. If it clogs, you can expect the pressure to build up.
  • The Gaskets Or Seal Will Fail. This happens as a result of the pressure build-up. The excess pressure becomes too much for the seals to bear and they end up giving way.
  • Engine Oil Leaks. When the seals and gasket give in to the pressure, they create pathways for oil to leak. It can be noticed on your parking lot’s floor.

Check out this thorough article about a bad PCV valve

Can A Bad PVC Valve Cause High Oil Pressure?

When pressure builds up in the crankcase, the oil pressure might rise.

How Long Can I Drive With A Bad PVC Valve?

A bad PVC valve will not stop you from driving your car, you can drive but with full knowledge of all the critical facts. The more you retain the defective valve, the more oil you lose and the more you endanger your engine.

The distance you can get from your car with the bad PVC valve depends on its age and other factors. Experts say you can get anywhere around 550-55000 miles of distance, and engine damage of course.

Cost Of Replacing A Worn PVC Valve

The costs of replacing a PVC valve range from $60 to $83. This is inclusive of the part’s purchase price and labor costs but exclusive of taxes.

Bottom Line

The PVC valve is as much a critical part of the engine as any other part. It seldom develops problems and maybe that’s why they are most of the time ignored during regular inspections.

We have seen the adverse effects that can result from a faulty PVC valve, even the engine itself is not safe. The amount of oil lost through leaks can amount to a tangible figure if not contained. As you have other parts serviced, tell your mechanic to check the PVC system too.

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