Mechanical Inspection: Compression
Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. Release fuel system pressure before checking engine compression. See FUEL SYSTEM .
COMPRESSION SPECIFICATIONS
| Application | Specification | ||||
|---|---|---|---|---|---|
| Compression Ratio | |||||
| 4.0L | |||||
| Base Engine | 10.0:1 | ||||
| Supercharged Engine | 8.5:1 | ||||
| 6.0L | 11.0:1 | ||||
| Compression Pressure (1) | |||||
| 4.0L | 157-167 psi (11.0-11.7 kg/cm2 ) | ||||
| 6.0L | 194-232 psi (13.6-16.3 kg/cm2 ) | ||||
| Maximum Variation Between Cylinders | |||||
| 4.0L | 10 psi (.70 kg/cm2 ) | ||||
| 6.0L | 20 psi (1.40 kg/cm2 ) | ||||
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