Engine Compression

Check engine compression with engine at normal operating temperature at specified cranking speed, all spark plugs removed and throttle wide open.

CAUTION: Release fuel system pressure before checking engine compression.

COMPRESSION SPECIFICATIONS

Application

Specification

Compression Ratio

4.0L

9.5:1

6.0L

11.0:1

Compression Pressure ⁽¹⁾

4.0L

160-170 psi (11.2-12.0 kg/cm² )

6.0L

200-240 psi (14.1-16.9 kg/cm² )

Maximum Variation Between Cylinders

10 psi (.70 kg/cm² )

⁽¹⁾	Minimum cranking speed is 300 RPM with all spark plugs removed and throttle held wide open.