Ford Tempo/Topaz 1984-1994 Repair Guide

Crankcase Ventilation System



See Figure 1

The Positive Crankcase Ventilation (PCV) system incorporated into the gasoline and diesel engine cycles crankcase gases back through the engine where they are burned. The PCV valve regulates the amount of ventilating air and blow-by gas to the intake manifold and also prevents backfire from traveling into the crankcase. The PCV valve should always be mounted in a vertical position. On some engine applications, the PCV system is connected with the evaporative emission system.

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Fig. Fig. 1: A vapor flow through path in a typical PCV system


See Figure 2

Stuck PCV Valve Check
  1. With the engine OFF. Remove the PCV valve from the grommet and hose.
  3. Shake the PCV valve.
    1. Inspect the base of the valve for any obstructions.
    3. If the valve rattles when shaken, re-connect it.
    5. If it does not rattle, replace it.

  5. Start the engine and allow it to idle. Disconnect the hose from the air cleaner and check for vacuum at the hose. This can be accomplished by placing a finger over the hose, or using a vacuum gauge with the correct fitting to create an air-tight seal around the hose. If vacuum exists the system is functioning normally.
  7. If vacuum does not exist, the hose may be broken, the system may be plugged or the evaporative valve is leaking. Disconnect the evaporative hose, cap the tee and recheck the system. If the vacuum exists, the PCV system is functioning. Check the evaporative emission system.
  9. If vacuum still does not exist at the PCV, check for vacuum back through the system (filler cap, hoses). Also check the torque of the bolts securing the rocker cover. A loose rocker cover could cause a vacuum lose. Service the defective components as required.
  11. Reconnect the PCV valve into the hose and grommet, and check for proper operation.

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Fig. Fig. 2: A variety of PCV valves are used based upon the emissions equipment installed in the vehicle


See Figures 3 and 4

  1. Remove the valve, with the hose still attached from the rubber grommet using a rocking back and forth motion
  3. Loosen or remove the hose clamp securing the PCV valve to the hose. Use a twisting motion to remove the valve from the hose. Inspect the the hose and grommet, and replace if needed.

To install:
  1. Coat both ends of the PCV valve with oil, install the new valve into the hose, sliding the clamp into position, and finally install the valve into the rubber grommet.
  3. Start the car and check for any air leaks.

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Fig. Fig. 3: Remove the PCV valve from the retaining grommet with a back and forth motion ...

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Fig. Fig. 4: ... then remove any breather hose which is attached to the PCV valve