For 1990-2009 cars

A closed crankcase ventilation system is used to provide a more complete scavenging of crankcase vapors. Fresh air from the air cleaner is supplied to the crankcase, mixed with blow-by gases and then passed through a crankcase ventilation valve into the intake manifold.

### Typical Crankcase Ventilation Valve Flow

(1) | To Intake Manifold
(2) | Crankcase Ventilation Valve Hose
(3) | Postive Crankcase Ventilation Valve (PCV)
(4) | Crankcase Vent Hose
(5) | To Throttle Body

The primary control is through the crankcase ventilation valve which meters the flow at a rate depending on manifold vacuum. To maintain idle quality, the crankcase ventilation valve restricts the flow when intake manifold vacuum is high. If abnormal operating conditions arise, the system is designed to allow excessive amounts of blow-by gases to back flow through the crankcase vent tube into the engine air inlet to be consumed by normal combustion.

### PCV Cutaway

(1) | Check Valve

### Results of Incorrect Operation

A plugged PCV valve or hose may cause:

• | Rough idle

• | Stalling or slow idle speed

• | Oil leaks

• | Sludge in engine

A leaking valve or hose would cause:

• | Rough idle

• | Stalling

• | High idle speed