Mechanical Inspection: Compression

NOTE: Ensure battery is fully charged to obtain specified cranking speed.

NOTE: If cylinder compression in one or more cylinders is low, repeat inspection using a small amount of oil poured into each cylinder. If compression pressure increases, piston rings may be worn or damaged. If compression pressure does not increase, a valve may be sticking or seating improperly. If compression in any 2 adjacent cylinders is low and does not change after oil is added, cylinder head gasket may be leaking.

Start engine and warm to normal operating temperature. Turn ignition off. Release fuel pressure. See FUEL SYSTEM . Remove all ignition coils.
On all models, remove all spark plugs. Depress accelerator pedal fully to hold throttle valve wide open. Use Compression Gauge Adapter (J45402) or suitable rubber tipped adapter that is less than.79" (20.0 mm) in diameter.
On all models, attach compression tester to cylinder No. 1. Crank engine at specified speed and record highest gauge indication. See COMPRESSION SPECIFICATIONS table. Repeat measurement for each cylinder.

COMPRESSION SPECIFICATIONS ⁽¹⁾

Application

psi (kg/cm² )

FX35, FX45, M45 & Q45

Standard

191 (13.5)

Minimum

164 (11.5)

Maximum Variation Between Cylinders

14 (1.0)

G35

Standard

185 (13.0)

Minimum

156 (11.0)

Maximum Variation Between Cylinders

14 (1.0)

I35 & QX4

Standard

185 (13.0)

Minimum

142 (10.0)

Maximum Variation Between Cylinders

14 (1.0)

⁽¹⁾	With engine at 300 RPM.