Mechanical Inspection: Compression
Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer. See engine analyzer manual for specific instructions.
WARNING:
DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate engine oiling system.
COMPRESSION SPECIFICATIONS (1)
| Application | psi (kg/cm2 ) | |||
|---|---|---|---|---|
| G20 | ||||
| Standard | 178 (12.5) | |||
| Minimum | 149 (10.2) | |||
| Maximum Differential | 14 (1.0) | |||
| M30 | ||||
| Standard | 173 (12.2) | |||
| Minimum | 128 (9.0) | |||
| Maximum Differential | 14 (1.0) | |||
| Q45 | ||||
| Standard | 185 (13.0) | |||
| Minimum | 142 (10.0) | |||
| Maximum Differential | 14 (1.0) | |||
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