GM: Electra/Park Avenue/Ninety-Eight 1990-1993

Positive Crankcase Ventilation System

Print



Click image to see an enlarged view

Fig. Fig. 1 The pcv valve doubles as a check valve



Click image to see an enlarged view

Fig. Fig. 2 pcv system schematic-Vin C engine



Click image to see an enlarged view

Fig. Fig. 3 pcv valve location-Vin C engine



Click image to see an enlarged view

Fig. Fig. 4 pcv system schematic-Vin L engine



Click image to see an enlarged view

Fig. Fig. 5 pcv valve location-Vin L engine



Click image to see an enlarged view

Fig. Fig. 6 pcv system schematic-Vin 1 engine



Click image to see an enlarged view

Fig. Fig. 7 pcv valve location-Vin 1 engine

OPERATION



The Positive Crankcase Ventilation (pcv) system is used on all vehicles to consume the crankcase vapors in the combustion process rather than allowing them to vent to the atmosphere. Fresh air from the throttle body is supplied to the crankcase, mixed with blow-by gases and then passed through a Positive Crankcase Ventilation valve into the intake manifold.

When manifold vacuum is high, such as at idle, the valve restricts the flow of blow-by gases allowed into the manifold. If abnormal operating conditions occur, the system will allow excessive blow-by gases to back flow through the hose into the crankcase vent tube and into the throttle body to be consumed by normal combustion.

A plugged pcv valve or hose may cause rough idle, stalling or slow idle speed, oil leaks, or sludge in the engine. A leaking valve could cause rough idle, stalling or high idle speed. The condition of the grommets in the intake manifold will also affect system and engine performance.

Proper operation of this system is dependent upon a well sealed engine. With this system, any blow-by in excess of the system's capacity is exhausted into the intake manifold and is drawn into the engine. If oil sludging or dilution is noticed (but the pcv system is functioning properly) check the engine for mechanical wear-related problems. A malfunctioning or non functioning pcv system can damage your engine-be sure to maintain it properly.

FUNCTIONAL CHECK



1990 Engine (VIN C)
  1. Remove the pcv valve from the intake manifold.
  2.  
  3. Run the engine at idle.
  4.  
  5. Place your thumb over the end of the pcv valve. If there is no vacuum, check for a plugged valve, hose, or manifold port. Replace all questionable parts.
  6.  
  7. Turn the engine off and remove pcv valve.
  8.  
  9. Shake the valve and listen for a rattling noise. If the valve does not rattle, replace the valve.
  10.  

1991-93 Engines (VINS L & 1)
  1. Turn the engine off and remove pcv valve.
  2.  
  3. Shake the valve and listen for a rattling noise.
  4.  
  5. If the valve does not rattle, replace the valve.
  6.  

 
label.common.footer.alt.autozoneLogo