Mechanical Inspection: Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an 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 are triggered by the ignition switch during cranking mode, which can cause a fire hazard, or contaminate the engine's oiling system.

COMPRESSION SPECIFICATIONS

Application

Specification

Compression Ratio

XJS

11.5:1

XJ6

9.6:1

Compression Pressure

XJS ⁽¹⁾

200-220 psi (14.1-15.5 kg/cm² )

XJ6 ⁽²⁾

160-170 psi (11.2-12.0 kg/cm² )

⁽¹⁾	Information on maximum compression pressure variation between cylinders is not available.

⁽²⁾	Maximum variation between cylinders is 10 psi (.70 kg/cm² ).