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 MANUALSCHEVROLET2012CHEVY EXPRESS G2500, VAN PASSENGER, 4.8L ENG VIN AREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1854 (ENGINE MECHANICAL - 6.6L (LMM) - DIAGNOSTIC INFORMATION AND PROCEDURES)DIAGNOSTIC INFORMATION AND PROCEDURESENGINE COMPRESSION TESTTEST PROCEDURE
2012 Chevrolet Chevy Express G2500, Van Passenger, 4.8L Eng VIN A
Test Procedure
2012 Chevrolet Chevy Express G2500, Van Passenger, 4.8L Eng VIN ASECTION Test Procedure
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2010 GMC Savana Special, 2010 GMC Savana Camper Special, 2010 GMC Savana, 2010 Chevrolet RV Cutaway, and 2010 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
- Ensure that the vehicle's batteries are in good condition, and fully charged.
- Operate the vehicle until the engine is at normal operating temperature.
- Shut off engine.
- Disconnect glow plug nut; remove all 8 glow plugs. All 8 glow plugs must be removed from the engine during each cylinder test to obtain valid test results.
- Prior to taking a compression reading, verify the cranking speed is greater than 140 RPM. If the cranking speed is below 140 RPM, repair the slow cranking speed condition before continuing with the compression test. Refer to Engine Cranks Slowly .
- Install the EN-47603: adapter in the glow plug hole for the cylinder that is being checked.
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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.