AMC Coupes/Sedans/Wagons 1975-1988 Repair Information

PCV System


PCV means Positive Crankcase Ventilation. This is a simple emission control system which routes crankcase fumes into the intake manifold or carburetor to be burned. A clogged PCV system will cause poor idle and rough running. There are two points of maintenance in this system: A valve and a filter. Maintenance intervals are shown in the `Service Intervals' chart, but remember that this system can clog pretty quickly on an older engine that is using a little oil.


See Figures 1, 2 and 3

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Fig. Fig. 1: Typical PCV system components4 Cyl 121 engine

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Fig. Fig. 2: PCV system assembly6 Cyl 232 and 258 engines (4 Cyl 151 system is similar); 1980-82 models do not have the purge hose

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Fig. Fig. 3: Common V8 engine PCV system

On a six, the PCV valve is at the cover end of a hose leading from just below the carburetor to the valve cover. On a 4-151 or V8, it is at the intake manifold end of a hose leading from the carburetor to the intake manifold.

  1. Pull the valve from its grommet in the intake manifold (V8) or valve cover (six).
  3. Loosen the hose clamp and pull the valve from the hose. The valve can be washed in kerosene, but the best plan is to replace it. If the valve seems really sludged up, check the hose, too.
  5. Push the new or cleaned valve into its hose. Push the valve into its grommet. The condition of this grommet is important. If it leaks air, the engine will idle too fast because of a lean fuel/air mixture.


To clean the system filter:

  1. On a six, remove the top of the air cleaner as explained previously under `Air Cleaner.' Turn the top upside down and pull the filter out of the hose, inside the top. Don't pull the hose off first, or you'll damage it. Wash the filter in kerosene and replace it when dry. Replace the top of the air cleaner.
  3. On a 4-151 or V8, remove the oil filter cap and wash it with kerosene. The cap contains the filter element. Replace it when dry.