Diagnosis and testing

Pcv valve test-3.9/5.2/5.9L engine

(1) With engine idling, remove the PCV valve from cylinder head (valve) cover. If the valve is not plugged, a hissing noise will be heard as air passes through the valve. Also, a strong vacuum should be felt at the valve inlet (Fig. 15).

Fig. 15 Vacuum Check at PCV Valve-Typical

1 - PCV VALVE GROMMET

2 - PCV HOSE

3 - PCV VALVE

4 - VACUUM MUST BE FELT AGAINST FINGER

5 - ENGINE VALVE COVER

(2) Return the PCV valve into the valve cover.

Remove the fitting and air hose at the opposite valve cover. Loosely hold a piece of stiff paper, such as a parts tag, over the opening (rubber grommet) at the valve cover (Fig. 16).

(3) The paper should be drawn against the opening in the valve cover with noticeable force. This will be after allowing approximately one minute for crankcase pressure to reduce.

(4) Turn engine off and remove PCV valve from valve cover. The valve should rattle when shaken (Fig. 17).

Fig. 16 Vacuum Check at Valve Cover Opening

1 - STIFF PAPER PLACED OVER RUBBER GROMMET

2 - RUBBER GROMMET

3 - VALVE COVER

4 - FITTING REMOVED FROM VALVE COVER

5 - AIR TUBE

Fig. 17 Shake PCV Valve-Typical

1 - PCV VALVE GROMMET

2 - PCV VALVE

3 - PCV VALVE MUST RATTLE WHEN SHAKEN

(5) Replace the PCV valve and retest the system if it does not operate as described in the preceding tests. Do not attempt to clean the old PCV valve.

(6) If the paper is not held against the opening in valve cover after new valve is installed, the PCV valve hose may be restricted and must be replaced.

The passage in the intake manifold must also be checked and cleaned.

(7) To clean the intake manifold fitting, turn 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.

Pcv valve/pcv system test-4.7L v-8 engine

(1) Disconnect PCV line/hose (Fig. 18) by disconnecting rubber connecting hose at PCV valve fitting.

(2) Remove PCV valve at oil filler tube by rotating PCV valve downward until locating tabs have been freed at cam lock (Fig. 18). 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 (Fig. 18). 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 (Fig. 18) 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 left side of air cleaner resonator box (Fig. 19).

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 breather (Fig. 19). Check for obstructions or restrictions.

(14) If vacuum is still not present, remove each PCV system breather (Fig. 19) from each cylinder head. Check for obstructions or restrictions. If plugged, replace breather. Tighten breather to 12 N*m (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 check for obstructions or restrictions.

Fig. 18 PCV Valve/Oil Filler Tube-4.7L V-8 Engine

1 - O-RING

2 - LOCATING TABS

3 - CAM LOCK

4 - OIL FILLER TUBE

5 - PCV LINE/HOSE

6 - PCV VALVE

VACUUM SCHEMATICS

A vacuum schematic for emission related items can be found on the Vehicle Emission Control Information (VECI) label. For label location, refer to Vehicle Emission Control Information (VECI) Label.

Leak detection pump (ldp)

Refer to the appropriate Powertrain Diagnostic Procedures service manual for LDP testing procedures.

Fig. 19 PCV Breathers/Tubes/Hoses-4.7L V-8 Engine

1 - FRESH AIR FITTING

2 - CONNECTING TUBES/HOSES

3 - CRANKCASE BREATHERS (2)

4 - RUBBER HOSE

5 - AIR CLEANER RESONATOR