Disassembly & Inspection

Disassemble pump. Measure O.D. of inner rotor shaft portion and outer rotor O.D. Measure clearance between outer rotor and cylinder block housing.
Measure case projection height "H1" plus inner and outer rotors "H2". See Fig 1 . Measure housing bore depth "L" of cylinder block. To determine side clearance "C", use the following formula: "C" = "L"- ("H1" + "H2").

Fig 1: Measuring Oil Pump Clearances
Courtesy of SUBARU OF AMERICA, INC.
Side clearance must be within specification. See OIL PUMP SPECIFICATIONS table. If side clearance is not within specification, replace inner and outer rotors with proper rotors. See ROTOR SPECIFICATIONS table.
Check relief valve spring free length. Replace components if not within specification. See OIL PUMP SPECIFICATIONS table.

OIL PUMP SPECIFICATIONS

Application

In. (mm)

Case Projection Height "H1"

.3138-.3150 (7.971-8.001)

Outer Rotor-to-Cylinder Block

⁽¹⁾ .0039-.0071 (.099-.180)

Relief Valve Spring Free Length

1.854 (47.092)

Rotor Housing Depth "L"

.8646-.8677 (21.961-22.039)

Rotor O.D

Inner

1.4035-1.4055 (35.649-35.699)

Outer

1.9665-1.9685 (44.949-49.999)

Side Clearance "C"

⁽²⁾ .0020-.0063 (.051-.160)

⁽¹⁾	Wear limit is .0087" (.221 mm).

⁽²⁾	Wear limit is .0071" (.180 mm).

ROTOR SPECIFICATIONS