Engine Compression Test
WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.
Perform the following steps in order to conduct a compression test for VIN 4:
- Conduct the following steps in order to check cylinder compression:
- 1.1. Engine should be at room temperature.
- 1.2. Disconnect wiring from the ignition module.
- 1.3. Remove the spark plugs.
- 1.4. Throttle body valve should be wide open.
- 1.5. 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 689 kPa (100psi).
Important: 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 low on first stroke. Tends to build up on following strokes but does not reach normal. Improves considerably with addition of oil.
- Valves - Compression low on first stroke. Does not tend to build up on the following strokes. Does not improve much with addition of oil. Use approximately three squirts from a plunger-type oiler.