Mechanical Inspection: Compression

Check engine mechanical condition with compression gauge, vacuum gauge, or engine analyzer. See engine analyzer manual for specific instructions. For compression specifications, see SERVICE & ADJUSTMENT SPECIFICATIONS - TRUCKS article.

WARNING: Fuel injectors on many models are triggered by ignition switch during cranking mode. DO NOT use ignition switch during compression tests. Use remote starter to crank engine to prevent fire hazard or contamination of engine's oiling system.