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 MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 139 (ENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURES - 2.2L)PRELIMINARY INSPECTION & ADJUSTMENTSMECHANICAL INSPECTIONCOMPRESSION
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8
Mechanical Inspection: Compression
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Compression
WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
The results of a compression test will fall into the following categories:
- Normal Compression builds up quickly and evenly to specified compression on each cylinder.
- Piston Rings Compression is low on the first stroke, tends to build up on following strokes, but does not reach normal. Compression improves considerably with the addition of oil.
- Valves Compression is low on the first stroke, does not tend to build up on the following strokes, and does not improve much with the addition of oil. Use approximately three squirts from a plunger-type oiler.
- Conduct the following steps in order to check cylinder compression:
- Engine should be at room temperature.
- Disconnect wiring from the ignition module.
- Remove the spark plugs.
- Throttle body valve should be wide open.
- Battery should be at or near full charge.
- For each cylinder, crank engine through four compression strokes.
- The lowest reading cylinder should not be less than 70 percent of the highest.
- No cylinder reading should be less than 100 psi (689 kPa).
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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.