FAQ : How to Check Your PCV Valve

October 23, 2013

Some of the most common questions we receive here at Pro Street have to do with the positive crankcase ventiliation PCV Valve and how to troubleshoot it if your vehicle is smoking, or exhibiting a fluctuating idle.

What is the PCV Valve?

The valve is a one way check valve usually made of metal or plastic that controls the levels of gases that are created from the natural process of your vehicle running. While your engine is running, there is a certain amount of gases and fuel that can make their way past the rings and into the crankcase itself. These gases, if left unchecked will ruin your oil and could cause issues with how your vehicle runs.

The PCV releases these gases and reroutes them back into your intake tract so that the excess gas and fuel can be consumed by your combustion process. Your PCV helps with fuel economy, improves ring seal and keeps your vehicle environment friendly.

How do I find my PCV Valve?

Most fuel injected vehicles have the valve located on the intake manifold or mounted onto the valve cover(s), although the valve may be located in a vacuum line from the valve cover to the intake manifold itself.

For carbureted vehicles the PCV would be found that leads from the bottom are of the carburetor to the top of the valve cover or the oil filler hole.

How can I tell it’s my PCV Valve?

There should be a hose leading from this valve as fumes are pulled out of the crankcase and motor and into the intake manifold through your valve cover. It’a also a good idea to replace any hoses or clamps that may be associated with this part and the lines going to the intake manifold.

How do I check my valve? How do I know my PCV is bad?

Testing your PCV Valve is very easy and a straightforward affair.

1. Locate your valve in your engine bay, and turn on your vehicle. With the engine running at idle, pinch closed the vacuum line that leads from your PCV to your intake manifold. You should hear the RPM’s audibly dip as you pinch this line. If nothing is happening, replacing your PCV should resolve your issue.

2. Find your PCV, and remove it from the valve cover with the hose leading to the intake manifold still connected to it. You should feel suction from the inlet of the valve at idle.