Five-dollar part on top of the valve cover. Shake test - rattles when good, mute when failed. Replace every 30k.
The Positive Crankcase Ventilation valve on the 4.0L sits in a rubber grommet on the valve cover and connects via a short hose to the intake manifold. It vents crankcase blow-by gases back into the intake. A failed PCV produces rough idle, oil consumption, blown gaskets (especially the rear main and valve cover), and a wet driver-side foot-well from oil-misted blow-by reaching the throttle body. Pull the valve out, shake it - a healthy PCV rattles loosely. A failed one is silent (stuck open or closed). Replace with Mopar 33002973 or Fram FV191. Five minute job, no special tools. Verify the small breather hose from the cap to the air intake tube is intact too - cracked hoses cause unmetered air leaks.
| Part | Vendor | Est. price |
|---|---|---|
| PCV valve Mopar | Mopar | ~$8 |
Written and maintained by an AZ wheeler and driveway wrencher. Always cross-reference your factory service manual — modifications affect vehicle safety and warranty. Work at your own risk.