Section 3.2
Oil Pump

The gear-type oil pump is mounted to the cylinder block and is gear driven from the front end of the crankshaft. See Figure "Oil Pump Mounting" .‪

Figure 1. Oil Pump Mounting

Effective with 1991 model year engines, the design of the oil pump has been changed. The current oil pump is smaller, and contains a relief valve. See Figure "Lubricating Oil Pump and Parts - 1991 & Later Engines" . On both current and former design oil pumps, the helical gears rotate inside a housing. see Figure "Lubricating Oil Pump Parts (Pre-1991 Engines)" for the former oil pump.‪

The drive gear is pressed on the drive shaft, which is supported inside the housing on two bushings. The driven gear is pressed on the driven gear shaft, which is supported inside the housing on two bushings.‪

Figure 2. Lubricating Oil Pump and Parts - 1991 & Later Engines

Figure 3. Lubricating Oil Pump Parts (Pre-1991 Engines)

An inlet pipe assembly, with screen, is attached to the inlet opening in the pump body. The screen end of the inlet pipe assembly is supported with brackets mounted to the cylinder block.‪

The inlet screen is located below the oil in the pan and serves to strain out any foreign material which might damage the pump.‪

Section 3.2.1
Repair or Replacement of Oil Pump

To determine if repair is possible or replacement is necessary, perform the following procedure. See Figure "Flowchart for Repair or Replacement of Oil Pump" .‪

Figure 4. Flowchart for Repair or Replacement of Oil Pump

Section 3.2.2
Removal of Oil Pump

Remove the oil pump as follows:‪

1. Remove the drain plug from the oil pan and drain the oil. Refer to "14.6.1 Lubricating Oil" .
2. Remove the oil pan bolts, isolators, sleeves and washers, and oil pan. Refer to "3.11.2 Removal of Oil Pan" .

   NOTICE:
   The thru-bolts must be loosened first to prevent twisting the oil pick-up tube. Failure to do this could cause eventual stress-crack damage at the pick-up tube to flange joints.‪

3. Loosen but do not remove the thru-bolts securing the oil pump bracket to the pick-up tube.
4. Remove the two bolts that secure the oil pump pick-up tube support bracket to the cylinder block.
5. Remove the two bolts securing the oil pump pick-up tube to the oil pump.
6. Tap the pick-up tube gently to loosen it from the gasket and remove the pipe.
7. Remove the two bolts securing the outlet pipe to the pump and cylinder block.
8. Tap the outlet pipe gently to loosen it from the gaskets and remove the pipe.

   NOTICE:
   If removing the oil pump from the vehicle, loosen the bolts; but leave them in place to prevent the pump from falling, before the mechanic removes the oil pump.‪

9. Remove the four bolts retaining the oil pump to the cylinder block.
10. If necessary, pry gently on the oil pump assembly to loosen it from the block.

    Note: Remove and save the shims, if used, between the oil pump mounting feet and the cylinder block. The shims are used to adjust the oil pump drive gear-to-crankshaft timing gear lash.

Section 3.2.3
Disassembly of Oil Pump

Observe the position of all parts including the oil pick-up tube and outlet pipe during disassembly to facilitate reassembly of the pump.‪

Disassemble the oil pump as follows:‪

1. Remove the two bolts securing the oil pressure relief valve to the oil pump housing.
2. Tap the relief valve lightly to loosen it from the gasket and the oil pump housing (pre-1991 engines only).
3. Use a two-jaw puller to remove the oil pump drive gear from its shaft.
4. Remove the four oil pump cover bolts.
5. Remove the oil pump cover.
6. Remove the drive gear and shaft assembly, and the driven gear shaft and assembly from the oil pump housing.

Section 3.2.3.1
Inspection of Oil Pump

Inspect the oil pump as follows: ‪

EYE INJURY ‪
To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.‪

1. Wash all parts in clean fuel oil and dry them with compressed air.
2. Remove any gasket material from the oil pump housing at relief valve, inlet pipe and outlet pipe mating surfaces.

   EYE INJURY ‪
   To avoid injury from flying debris when using compressed air, wear adequate eye protection (face shield or safety goggles) and do not exceed 276 kPa (40 psi) air pressure.‪

3. Clean the outlet and inlet pipe and screen assembly in clean fuel oil and blow dry with compressed air.
4. Measure the bushing clearance in the pump body and cover.
   1. If the shaft-to-pump cover bushing clearance exceeds 0.089 mm (0.0035 in.), replace bushing.
   2. If the shaft-to-pump cover bushing clearance is within 0.089 mm (0.0035 in.), reuse the bushing.

   NOTICE:
   The use of excessively worn gears will result in low engine oil pressure that, in turn, may lead to serious engine damage.‪

5. Visually inspect the oil pump gear. Check to see if the gear turns freely in the pump housing.
   1. If the gear binds, replace it with a new gear.
   2. If the gear does not bind, reuse the gear.
6. Visually inspect gear teeth on drive shaft bushing contact areas. Check for worn contact areas on gear teeth and drive shaft.
   1. If the area is worn, replace gear and drive shaft with new parts.
   2. If the area is not worn, reuse the parts.

Section 3.2.4
Assembly of Oil Pump (1991 and Later Engines)

Assemble the oil pump as follows:‪

1. Lubricate the drive shaft bushing with clean engine oil.
2. Insert the drive shaft and gear assembly into the pump body. See Figure "Lubricating Oil Pump and Parts - 1991 & Later Engines" .
3. Position the oil pump assembly on a press, pump body down, supporting the drive shaft. The pump body should be free of the press bed supported by the pump gear contacting the bottom of the pump cavity.
4. Coat the bore of the drive gear with a light film of Lubriplate (or equivalent).
5. Position drive gear squarely on the end of the shaft.
6. Press the drive gear onto the shaft until a clearance of 1.00 mm (0.039 in.) is obtained between the inner face of the gear and the pump body. See Figure "Oil Pump Drive Gear Installation" .
   

   Figure 5. Oil Pump Drive Gear Installation

   Note: A minimum press load of 6.7 kN (1,506 lb) must be obtained when pressing the gear onto the shaft. When completed, an end play of 0.84-1.12 mm (0.033-0.044 in.) must be obtained.

7. Lightly coat the driven gear bushing with clean engine oil.
8. Insert the drive shaft and gear assembly into the pump body. See Figure "Lubricating Oil Pump and Parts - 1991 & Later Engines" .
9. Lightly coat both bushings in the pump cover with clean engine oil.
10. Index them with the shafts.
11. Install the four cover bolts and hand-tighten.
12. Rotate the oil pump by hand. The oil pump must turn freely without binding.

    NOTICE:
    The cause of oil pump binding must be corrected before installation is complete or severe engine damage may result.‪

13. If binding occurs, stop assembly and disassemble until the cause can be detected and corrected. Refer to "3.2.3 Disassembly of Oil Pump" .
14. Torque the four cover bolts to 30-38 N·m (22-28 lb·ft).

Section 3.2.5
Assembly of Oil Pump (Pre-1991 Engines)

Assemble the oil pump as follows:‪

1. Lightly coat the drive shaft bushings with clean engine oil. See Figure "Oil Pump Drive Gear Installation" .
2. Insert the drive shaft and gear assembly into the pump body.
3. Position the oil pump assembly on a press, pump body down, supporting the drive shaft. The pump body should be free of the press bed supported by the pump gear contacting the bottom of the pump cavity.
4. Coat the bore of the drive gear with a light film of Lubriplate (or equivalent).
5. Position drive gear squarely on the end of the shaft.
6. Press the drive shaft until a clearance of 0.38 mm (0.015 in.) is obtained between the inner face of the gear and the pump body. See Figure "Oil Pump Drive Gear Installation (Pre-1991 Engines)" .

   Note: A minimum press load of 8.9 kN (2,000 lb) must be obtained when pressing the gear on the shaft. When completed, an end play of 0.25-0.51 mm (0.010-0.020 in.) must be obtained.

7. Lightly coat the driven gear shaft bushing with clean engine oil.
8. Insert the driven shaft and gear assembly into the pump body. See Figure "Lubricating Oil Pump Parts (Pre-1991 Engines)" .
   

   Figure 6. Oil Pump Drive Gear Installation (Pre-1991 Engines)

9. Lightly coat both bushings in the pump with clean engine oil.
10. Index them with the shafts.
11. Install the four cover bolts and hand-tighten.
12. Rotate the pump by hand. The oil pump must turn freely without binding.

    NOTICE:
    The cause of oil pump binding must be corrected before installation is complete or severe engine damage may result.‪

13. If binding occurs, stop assembly and disassemble until the cause can be detected and corrected. Refer to "3.2.3 Disassembly of Oil Pump" .
14. Torque the four cover bolts 30-38 N·m (22-28 lb·ft).

Section 3.2.5.1
Test Assembled Oil Pump

Test oil pump as follows:‪

1. Rotate the pump by hand. Check for binding.
   1. If binding occurs, disassemble oil pump again, refer to "3.2.3 Disassembly of Oil Pump" .
   2. If no binding occurs, reuse the pump.
2. With a dial indicator mounted on the pump mounting surface, rotate the gear and check the gear run-out. The run-out specification is 0.08 mm (0.003 in.).
   1. If run-out exceeds 0.08 mm (0.003 in.), disassemble oil pump. Refer to "3.2.3 Disassembly of Oil Pump" .
   2. If run-out is within specifications, reuse the pump.

Section 3.2.6
Installation of Oil Pump

Install the oil pump to the cylinder block as follows:‪

1. Position the oil pump on the cylinder block so that the drive gear of the oil pump meshes with the crankshaft drive gear. The two dowels in the oil pump mounting feet should be positioned in the mating holes in the cylinder block.
2. Install the four bolts through the mounting feet of the pump into the cylinder block. Torque the bolts to 58-66 N·m (43-49 lb·ft) using the torque sequence shown. See Figure "Oil Pump Bolt Torque Sequence" .
   

   Figure 7. Oil Pump Bolt Torque Sequence

3. Fasten a dial indicator and magnetic base to the cylinder block so that the indicator tip rests on a tooth of the oil pump drive gear. See Figure "Oil Pump Drive Gear-to-Crankshaft Gear Lash Measurement" .
   

   Figure 8. Oil Pump Drive Gear-to-Crankshaft Gear Lash Measurement

   1. Proper clearance between the crankshaft gear and the oil pump drive gear is 0.051-0.229 mm (0.002-0.009 in.).

   Note: This gear clearance measurement must be done with the engine in upright position. When adjusting for gear tooth clearance by installing or removing shims, the same number of shims must be changed under each foot so that the pump will always be level on the engine block.

   2. Remove or install shims as necessary to obtain proper gear lash. The insertion or removal of one 0.127 mm (0.005 in.) shim will change the gear tooth clearance by approximately 0.089 mm (0.0035 in.).
4. Install the oil pressure regulator valve to the block. Refer to "3.3.5 Installation of Oil Pressure Regulator Valve" .
5. When attaching the pump outlet pipe to the oil pump housing and the cylinder block, none of the bolts should be tightened until all of the bolts have been started.
6. Install new gaskets and seals between the oil pump housing and outlet pipe and between the outlet pipe and cylinder block.
7. Torque the elbow-to-block bolts first then the elbow-to-pump bolts to 30-38 N·m (22-28 lb·ft).
8. Install a new gasket between the oil pump housing and pick-up tube.
9. Install and torque the two bolts, with washers attached, to 30-38 N·m (22-28 lb·ft).

   NOTICE:
   The thru-bolts must remain loose until last, to prevent twisting the oil pick-up tube. Failure to do this could cause eventual stress-crack damage at the pick-up tube to flange joints.‪

10. Install and torque the two pick-up tube support bracket-to-engine block bolts to 58-73 N·m (43-54 lb·ft).
11. Torque the two thru-bolts at the inlet pipe to support bracket to 58-73 N·m (43-54 lb·ft).
12. Recheck all bolts for tightness to ensure there will be no leaks in the oil pump and pipe mounting connections.
13. Install the oil pan. Refer to "3.11.4 Installation of Oil Pan" .
14. Fill the crankcase to the proper level with the recommended oil. Refer to "5.2.1 Lubricant Requirement" .
15. Refer to "12.3 Running" for verification of proper oil pump installation.