Toyota Pick-ups/Land Cruiser/4Runner 1970-1988

PCV Valve

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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.

The PCV system will not function properly unless the oil filler cap is tightly sealed. Check the gasket on the cap and be certain it is not leaking. Replace the cap or gasket or both if necessary to ensure proper sealing.

REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5 and 6

  1. Check the ventilation hoses and lines for leaks or clogging. Clean or replace as necessary.
  2.  
  3. Locate the PCV valve in the cylinder head cover and remove it by pulling it upward.
  4.  
  5. Blow into the crankcase end of the valve. There should be free passage of air through the valve.
  6.  
  7. Blow into the intake manifold end of the valve. There should be little or no passage of air through the valve.
  8.  
  9. If the PCV valve failed either of the preceding two checks, it will require replacement.
  10.  
  11. To install, simply slip the hose back onto the proper end of the PCV valve and then press it into the retaining grommet in the cylinder head cover.
  12.  
  13. For further information on the PCV system, please refer to Emission Controls .
  14.  

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 visible damage. Blow through the orifices to make sure they are not blocked. Replace any components as necessary.



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Fig. Fig. 1: Air should pass through the PCV valve when blowing into the crankcase side



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Fig. Fig. 2: Air should not pass through the PCV valve when blowing through the intake manifold side



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Fig. Fig. 3: PCV valves are located in the cylinder head cover



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Fig. Fig. 4: Check all PCV valve hoses, connections and cracks for cracks and brittleness



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Fig. Fig. 5: Removing the PCV valve hose



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Fig. Fig. 6: Removing the PCV valve

 
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