Chrysler Colt/Vista 1990-1993 Repair Information

PCV Valve and Crankcase Vent Filter


See Figures 1 and 2

Click image to see an enlarged view

Fig. Fig. 1: Removing the PCV valve hose

Click image to see an enlarged view

Fig. Fig. 2: Removing the PCV valve

A closed crankcase ventilation system is used on your car. The purpose of the closed system is to prevent blow-by gases, created by the engine, from escaping into the air.

Some models do not use a PCV Valve; blow-by gases are passed through a hose from the front of the valve cover to the air cleaner, and through another hose from the rear of the valve cover into the intake manifold. At part throttle, the blow-by gases are drawn from the rear of the valve cover into the intake manifold. At wide opened throttle, the blow-by gases are drawn through both the front and rear hose and returned to the engine.

Servicing the closed crankcase ventilation system on models without a PCV valve amounts to a periodic check of the hoses (cracked or hard hoses should be replaced) and the cleaning of the wire mesh in the air cleaner and the fixed orifice on the intake manifold. The wire mesh (resembles steel wool) acts as a filter for the crankcase ventilation system

On models equipped with a PCV valve, the PCV system supplies fresh air to the crankcase through the air cleaner. Inside the crankcase, the fresh air mixes with the blow-by gases. The mixture of fresh air and blow-by gases is then passed through the PCV valve and into the intake manifold. The PCV valve (usually mounted on the end of the valve cover) is a metered orifice that reacts to intake manifold vacuum, and has an adequate capacity for all normal driving conditions. However, under heavy engine loads or high speed driving there is less intake manifold vacuum and the blow-by gases exceed the PCV valve's capacity. When this happens, the blow-by gases back up into the air cleaner through the front hose, mix with fresh air and are reburned in the engine.


  1. Test the operation of the PCV valve, apply the parking brake, start the engine and allow it to operate at a normal idle speed.
  3. Remove the PCV valve from the valve cover mounting. A hissing noise should be heard as air passes through the valve and a strong vacuum should be felt if you place a finger over the opened end of the valve.
  5. To check the PCV valve with the engine not running, remove the PCV valve from the valve cover mounting. Shake the valve, if a rattling sound is heard, the valve is usually in operating condition.
  7. If a rattling sound is not heard, or, suction is not felt when the engine is running, the valve is clogged.
  9. Clean the valve and hose in solvent, check for air flow or rattle. Replace the valve and/or hose if necessary.