Positive Crankcase Ventilation: Testing and Inspection

DIAGNOSIS AND TESTING - PCV VALVE - 4.7L V-8




1. Disconnect PCV line/hose (5) by disconnecting rubber connecting hose at PCV valve fitting.

2. Remove PCV valve (6) at oil filler tube by rotating PCV valve downward until locating tabs (2) have been freed at cam lock. After tabs have cleared, pull valve straight out from filler tube. To prevent damage to PCV valve locating tabs, valve must be pointed downward for removal. Do not force valve from oil filler tube.

3. After valve is removed, check condition of valve O-ring (1). Also, PCV valve should rattle when shaken.

4. Reconnect PCV valve to its connecting line/hose.

5. Start engine and bring to idle speed.

6. If valve is not plugged, a hissing noise will be heard as air passes through valve. Also, a strong vacuum should be felt with a finger placed at valve inlet.

7. If vacuum is not felt at valve inlet, check line/hose for kinks or for obstruction. If necessary, clean out intake manifold fitting at rear of manifold. Do this by turning a 1/4 inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with shop air. If necessary, use a smaller drill to avoid removing any metal from the fitting.

8. Do not attempt to clean the old PCV valve.

9. Return PCV valve back to oil filler tube by placing valve locating tabs into cam lock. Press PCV valve in and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed towards rear of vehicle.

10. Connect PCV line/hose and connecting rubber hose to PCV valve.

11. Disconnect rubber hose from fresh air fitting at air cleaner resonator box. Start engine and bring to idle speed. Hold a piece of stiff paper (such as a parts tag) loosely over the opening of the disconnected rubber hose.

12. The paper should be drawn against the hose opening with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce.




13. If vacuum is not present, disconnect each PCV system hose at top of each crankcase breather (1). Check for obstructions or restrictions.

14. If vacuum is still not present, remove each PCV system crankcase breather from each cylinder head. Check for obstructions or restrictions. If plugged, replace breather. Tighten breather to 12 Nm (106 in. lbs.) torque. Do not attempt to clean breather.




15. If vacuum is still not present, disconnect each PCV system hose at each fitting, and at each check valve. Check for obstructions or restrictions.