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 MANUALSCHEVROLET2006COBALT SS, 4D SEDAN, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 186 (ENGINE MECHANICAL - 3.5L (L66))DIAGNOSTIC INFORMATION AND PROCEDURESENGINE COMPRESSION TESTCOMPRESSION TEST
2006 Chevrolet Cobalt SS, 4D Sedan, Standard
Compression Test
2006 Chevrolet Cobalt SS, 4D Sedan, StandardSECTION Compression Test
WARNING: This page is about a different car, the 2005 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
- Warm up the engine to a normal operating temperature of 98°C (208° F).
- Turn the ignition switch OFF.
- Remove the ignition coils. Refer to Valve Rocker Arm Cover Removal - Left and Valve Rocker Arm Cover Removal - Right .
- Remove the spark plugs.
- Attach the adapter (1), hose (2) and compression gage (3) to a spark plug hole.
- Connect a tachometer.
- Connect the scan tool.
- Turn the ignition switch to the ON position.
- Using the scan tool, command the injectors all off.
- Depress the accelerator pedal to open the throttle fully.
- Crank the engine with the starter motor and measure the compression.
- Perform the measurement on each cylinder and compare the readings.
Specification:
- Compression pressure: minimum 990 kPa (145 psi) at 200 RPM
- Maximum compression variation: 200 kPa (28 psi)
- If the compression is not within specifications, inspect for the following conditions and measure the compression again.
- Improperly adjusted valves
- Improperly positioned timing belt and sprockets
- Damaged or worn valves or seats
- Damaged cylinder head gasket
- Damaged or worn piston rings
- Damaged or worn piston and cylinder bore
- Using the scan tool, perform the PCM Reset Procedure to return the fuel injectors to normal operation.
RENDER: 1.0x
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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.