Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET2007HHR L4-2.2LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTEMISSION CONTROL SYSTEMSPOSITIVE CRANKCASE VENTILATIONDESCRIPTION AND OPERATION
2007 Chevrolet HHR L4-2.2L
Positive Crankcase Ventilation: Description and Operation
2007 Chevrolet HHR L4-2.2LSECTION Description and Operation
Crankcase Ventilation System Description
General Description
A crankcase ventilation system is used to consume crankcase vapors in the combustion process instead of venting them to atmosphere. Fresh air from the intake system is supplied to the crankcase, mixed with blow by gases and then passed through a calibrated orifice into the intake manifold.
Operation
The primary control is through the positive crankcase ventilation (PCV) orifice which meters the flow at a rate depending on inlet vacuum. The PCV orifice is an integral part of the camshaft cover. If abnormal operating conditions occur, the system is designed to allow excessive amounts of blow by gases to back flow through the crankcase vent into the intake system to be consumed by normal combustion.
Results of Incorrect Operation
A plugged orifice may cause the following conditions:
* Rough idle
* Stalling or slow idle speed
* Oil leaks
* Sludge in engine
A leaking orifice may cause the following conditions:
* Rough idle
* Stalling
* High idle speed
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.