engine

PCV Valve

for 1970 AMC Rebel Machine 390ci V8 · RWD

Editorial review:Chris Hackleman — Master Technician · 20+ years · Jeff Moore — Master Lexus & Toyota Mechanic · 20+ years

Difficulty

Easy

Time

18 min

Tools

Steps

✓Expert-verified. Personally reviewed and approved by OLP's master technicians (Chris Hackleman & Jeff Moore — 20+ years each). Always follow the vehicle's factory service information and torque specs.

Replacement of the positive crankcase ventilation (PCV) valve to maintain proper crankcase pressure and prevent oil contamination in the intake system.

Warnings

⚠Engine should be cool to the touch before beginning work to avoid burns from hot components

ℹ️A stuck or deteriorated PCV valve may require careful extraction to avoid breaking off in the valve cover grommet

Tools required

Needle nose pliersEssential

Shop towelsEssential

Flathead screwdriver

Parts

PCV valve × 1 — Use OEM specification for 390ci V8
PCV valve grommet × 1 — Replace if cracked or damaged

Preparation

Allow engine to cool completely
Open hood and secure with prop rod
Locate the PCV valve on the driver side valve cover, connected to the intake manifold via a rubber hose

Procedure

1
Disconnect PCV hose from valve
Grasp the rubber hose where it connects to the PCV valve at the valve cover. Twist gently while pulling to disconnect the hose from the PCV valve. If the hose is stuck, use needle nose pliers to carefully work it free without tearing the rubber.
2
Remove old PCV valve
Grip the PCV valve firmly and pull straight up out of the valve cover grommet. Use a twisting motion if resistance is encountered. The valve should pull free from the rubber grommet in the valve cover. If the valve is severely stuck, use needle nose pliers to grasp the base of the valve and work it out carefully.
3
Inspect grommet condition
Examine the rubber grommet remaining in the valve cover for cracks, hardening, or deterioration. The grommet should be pliable and free of splits. If damaged, carefully pry out the old grommet with a flathead screwdriver and press a new grommet into the valve cover opening by hand until it seats fully.
4
Test new PCV valve operation
Before installation, shake the new PCV valve and listen for a rattling sound from the internal check valve. This confirms the valve is functional. Cover one end with your thumb and blow through the opposite end - air should flow in one direction only.
5
Install new PCV valve
Push the new PCV valve straight down into the valve cover grommet until it seats firmly. The valve should be snug but not require excessive force. Ensure the valve is oriented with the connection nipple pointing toward the intake manifold hose.
6
Reconnect PCV hose
Push the rubber hose onto the PCV valve connection nipple until it seats completely. The hose should cover the ribbed section of the valve nipple fully. Ensure the opposite end of the hose is properly connected to the intake manifold fitting.

Reassembly

Verify all hose connections are secure and fully seated
Ensure no tools or parts are left in the engine bay

Verification

Start the engine and allow it to idle
Listen for any vacuum leaks or hissing sounds around the PCV valve area
Remove the oil filler cap while engine idles - there should be slight suction felt but not strong vacuum indicating the PCV system is functioning properly
Check for proper idle quality - rough idle may indicate incorrect PCV valve installation or vacuum leak

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