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 MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 143 (ENGINE CONTROLS - SYSTEM & COMPONENT TESTING)EMISSION SYSTEMS & SUB-SYSTEMS (DIESEL)POSITIVE CRANKCASE VENTILATION (6.6L)
2003 Chevrolet TrailBlazer 4.2 S, 4WD
Positive Crankcase Ventilation (6.6L)
2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Positive Crankcase Ventilation (6.6L)
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During normal operation, crankcase gases can be seen exiting from hose at oil separator. Maximum crankcase pressure is 16 in. H2 O (4 kPa) at 3100 RPM measured at oil level indicator tube.
- Oil Leak (External)
Check the following:- Plugged or kinked crankcase ventilation system hoses.
- Damaged or loose crankcase ventilation system hoses.
- Valve rocker arm diaphragm covers loose.
- Oil separator oil drain hose damaged or loose.
- Too much crankcase pressure.
- PVC Check Valve Stuck Closed
Check The following:- Valve closes when 0.213 psi (1.47 kPa) of crankcase pressure is applied from crankcase side (bottom) of valve.
- Valve should allow oil to drain from separator during idle and engine off conditions.
- Inspect for proper operation by stopping engine and waiting 5 minutes to allow oil to drain back into crankcase. Remove drain hose from check valve. If more than residual oil (several drops) drains from separator, replace valve.
- Odors
Normal situation. - Noise
Cracked hoses. - Smoke
Internal engine failure.
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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.