Toyota Corolla 1970-1987 Repair Guide

PCV Valve

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See Figure 1

Most gasoline engines covered by this manual are equipped with a Positive Crankcase Ventilation (PCV) valve. The PCV valve regulates crankcase ventilation during various engine operating conditions. At high vacuum (idle speed and partial load range) it will open slightly and at low vacuum (full throttle) it will open fully. This causes vapor to be removed from the crankcase by the engine vacuum and then sucked into the combustion chamber where it is dissipated.



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Fig. Fig. 1: Common PCV valve installation-the valve is usually mounted to a rubber grommet in the cylinder head (valve/camshaft) cover

On models with fuel injection there is no PCV valve. Vapor passage in the ventilation lines is controlled by two orifices. To check the PCV system on these models, inspect the hoses for cracks, leaks or other damage. Blow through the orifices to make sure they are not blocked. Replace all components as necessary

REMOVAL, INSTALLATION & INSPECTION

See Figures 2, 3, 4 and 5

  1. Check the ventilation hoses for leaks or clogging. Clean or replace as necessary.
  2.  
  3. Locate the PCV valve in the cylinder head cover or in the manifold-to-crankcase line. Carefully separate the hose(s), then remove the valve from the grommet (if mounted in the cylinder head cover).
  4.  
  5. Blow into the crankcase end of the valve. There should be a free passage of air through the valve.
  6.  



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Fig. Fig. 2: Disconnect the hose from the PCV valve



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Fig. Fig. 3: Remove the valve from the grommet in the cylinder head (camshaft/valve) cover

  1. Blow into the intake manifold end of the valve. There should be little or no passage of air through the valve.
  2.  
  3. If the PCV valve failed either of the preceding two checks, it will require replacement.
  4.  
  5. When installing the valve, make sure the hose(s), valve and grommet (if used) are all properly seated.
  6.  



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Fig. Fig. 4: Air should pass through the PCV valve when blowing in from the crankcase side



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Fig. Fig. 5: No air should pass the the valve when blowing from the intake manifold side

 
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