Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
PCV System: Operation
At part throttle, blow-by gas from the crankcase is drawn into the intake manifold through the rocker arm cover connecting hose of cylinders 2 and 4 and the PCV valve. At the same time, fresh air is drawn into the crankcase through the air cleaner and rocker arm cover connecting hose of cylinders 1 and 3, and routed to the intake manifold along with the blow-by gas.
At wide open throttle, when intake manifold vacuum is low, blow-by gas flows into the air cleaner through rocker arm cover connecting hose of cylinders 1 and 3, and is drawn into the carburetor.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.