Mazda Trucks 1972-1986 Repair Guide

PCV Valve


See Figures 1 and 2

Click image to see an enlarged view

Fig. Fig. 1: Schematic of the PCV system used on 1986 carbureted trucks

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Fig. Fig. 2: To remove the PCV valve, simply pull it free of the grommet and then remove the hose attached to the other end

The Positive Crankcase Ventilation (PCV) valve should be inspected for blockage periodically. On trucks through 1984, it is located in a special fitting in the intake manifold, just below the carburetor. On 1986 trucks, it is located in the valve cover, connected to the intake manifold by a vacuum hose.


The simplest test for the PCV valve is to remove it from its fitting and shake it. A distinct rattle should be heard; if not, replace the valve.


Through 1984
  1. Remove the air cleaner.
  3. Disconnect the hose from the PCV valve.
  5. Remove the valve from the special fitting in the intake manifold.
  7. Install the valve in the intake manifold fitting and connect the hose to the valve.
  9. Connect the hose to the air cleaner and install the air filter.
  11. Check for loose clamps or cracks in the PCV lines and replace the hoses if cracked.

1986 Vehicles

Simply pull the PCV valve from the grommet in the valve cover and remove the hose clamp. Then, pull it from the hose. Install the new valve and install the clamp.

If your engine exhibits lower than normal gas mileage and poor idle characteristics for no apparent reason, suspect the PCV valve. It is probably blocked and should be replaced.