How to tell if a PCV valve is bad on a Subaru?
If you own a Subaru, it's important to know how to identify a faulty PCV (Positive Crankcase Ventilation) valve. A bad PCV valve can cause various issues with your vehicle's performance and fuel efficiency. In this article, we'll provide a detailed guide on how to tell if your Subaru's PCV valve needs to be replaced.
What is a PCV Valve?
The PCV valve is a crucial component in your Subaru's engine that helps regulate the flow of crankcase vapors. It's responsible for recirculating these vapors back into the engine's intake system, where they can be burned off during the combustion process. A properly functioning PCV valve helps maintain the correct air-fuel ratio and prevents the buildup of harmful emissions.
Signs of a Bad PCV Valve
There are several common symptoms that may indicate a faulty PCV valve in your Subaru:
- Rough Idling: A bad PCV valve can cause your Subaru's engine to idle roughly or unevenly, as the incorrect airflow can disrupt the engine's normal operation.
- Decreased Fuel Efficiency: A malfunctioning PCV valve can lead to increased fuel consumption, as the engine may not be operating at its optimal efficiency.
- Oil Leaks: If the PCV valve is stuck open, it can allow engine oil to be drawn into the intake system, leading to oil leaks and potential engine damage.
- Excessive Oil Consumption: A faulty PCV valve can cause the engine to consume more oil than normal, as the crankcase vapors are not being properly recirculated.
- Check Engine Light: In some cases, a bad PCV valve may trigger the check engine light on your Subaru's dashboard, indicating a problem with the engine's emissions control system.
If you notice any of these symptoms, it's important to have your Subaru's PCV valve inspected and replaced if necessary.
How to Test a PCV Valve
To determine if your Subaru's PCV valve is faulty, you can perform a simple test:
- Locate the PCV valve, which is typically located on the valve cover or near the engine's intake system.
- With the engine running, gently pull on the PCV valve. If it moves freely and makes a clicking sound, it's likely functioning properly.
- If the PCV valve is stuck or doesn't move, it may be clogged or faulty and should be replaced.
It's also a good idea to visually inspect the PCV valve for any signs of damage, such as cracks or excessive wear. If the valve appears damaged, it's best to replace it to ensure proper engine operation.
Replacing the PCV Valve
Replacing a Subaru's PCV valve is a relatively straightforward process that can be done by most DIY mechanics. Be sure to consult your Subaru's service manual for specific instructions on how to access and replace the PCV valve. It's also important to use the correct replacement part, as using an incompatible valve can lead to further issues.
By understanding the signs of a bad PCV valve and how to properly test and replace it, you can help ensure your Subaru's engine continues to run smoothly and efficiently for years to come.
What is the lifespan of a PCV valve?
How often should you replace your PCV valve? There isn't a specific lifespan for a PCV valve, but you can usually plan to replace it anywhere between 20,000 and 50,000 of driving.
Will a new PCV valve make my car run better?
Whether you replace the valve yourself or have it taken care of by a professional during your next maintenance appointment, a clean, new valve will help your vehicle run smoother.
What is the diagnostic code for a bad PCV valve?
For instance, a PCV valve that sticks open may cause a check engine light. The diagnostic trouble codes or DTC will normally not mention the PCV valve. Instead, the diagnostic trouble code P0171 and P0174 are common.
Can a PCV valve be bad even if it rattles?
However, the fact is that if a PCV valve “rattles” when one shakes it, the moveable part that keeps the valve closed is no longer held in position under spring tension, which means that the valve is actually defective and useless.
How do I know if my Subaru PCV valve is bad?
If it the PCV valve is stuck open, the presence of smoke would correlate with high manifold vacuum such as when idling or engine braking. If your PCV rattles when you shake it, and there's no oil in your PCV hose (both signs of good PCV valve) that could mean bad valve seals and/or guides.
What are the symptoms of a oil breather pipe?
A breather pipe allows an internal combustion engine to vent crankcase pressure out of the engine. When an engine suffers from a clogged breather pipe, it can lead to several performance issues. The engine may overheat and begin to misfire. Oil consumption increases, and the engine seems to have less power.
Is it OK to drive with a bad PCV valve?
It's not advisable to drive with a bad PCV valve because it can cause the gaskets to blow.
What are the symptoms of a faulty PCV valve?
Faulty PCV Valve Symptoms
- Discolored exhaust gas that is white, black, or blue.
- A check engine light warning.
- Rough idling and acceleration.
- Whistling or hissing noises from the engine.
- Increased fuel consumption.
- Misfiring.
- Engine oil leaks.
What is the best way to test a PCV valve?
Once the engine is warm, disconnect the valve from the valve cover and use your finger to block the end of the valve. If you can feel the suction, and the idling drops slightly, the air flow is normal, the blockage has been cleared and the valve is operating as it should.
How often should a Subaru PCV valve be replaced?
The PCV valve is scheduled for cleaning/replacement every 30000 miles. At 120000 miles the hose will be rock hard so replacing both would be a good idea.
