Nissan Z - ZX 1970-1988 Repair Guide

PCV System

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

Every 12 months or 12,000 miles (19,000 km), whichever comes first, perform the following checks on the operation of the PCV system:

  1. Check the ventilation hoses for leaks or clogging and clean or replace as necessary.
  2.  
  3. Remove the ventilator hose from the PCV valve with the engine idling and place a finger over the valve inlet. If a strong vacuum is felt and a hissing noise is evident, the valve is functional; otherwise, replace it.
  4.  



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Fig. Fig. 1: PCV system-1970-74 models

On 1970-74 models, the PCV valve must be replaced every 12 months or 12,000 miles (19,000 km), whichever comes first. To replace the valve, unscrew it from it's fitting on the intake manifold with the proper size wrench and screw the replacement valve into the manifold. Replace any brittle or cracked hoses at the same time.



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Fig. Fig. 2: PCV system -1975-88 models



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Fig. Fig. 3: Remove the hose clamps attaching the breather hose to the PCV valve and rocker arm cover



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Fig. Fig. 4: With the clamps removed, slip the hose off the rocker arm cover and PCV valve connections



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Fig. Fig. 5: Remove the PCV valve from the intake manifold



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Fig. Fig. 6: If reinstalling the valve, check for clogged or distorted threads and clean/repair as necessary

On 1975-79 models, the valve must be replaced every 24 months or 24,000 miles (38,000 km). To replace the valve, simply disconnect it from its hose fittings and install a new valve into the hoses. Replace any brittle or cracked hoses at the same time.

On the 1980 and later models, no regularly scheduled replacement of the valve is called for. The valve must be replaced whenever it is clogged, as determined by the test given in Step 2. The valve is of the same type used on the 1975-79 models.

 
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