Chrysler Full-Size Trucks 1989-1996 Repair Guide

Oil Pump

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REMOVAL & INSTALLATION



2.5L Engine

See Figures 1 and 2

  1. Crank the engine around so that the No. 1 piston is at TDC. Disconnect the negative battery cable.
  2.  
  3. Matchmark the rotor to the block and remove the distributor to confirm that the slot in the oil pump shaft is parallel to the centerline of the crankshaft. Matchmark the slot to the distributor bore, if desired.
  4.  
  5. Remove the dipstick. Raise the vehicle and support safely. Drain the engine oil and remove the pan.
  6.  
  7. Remove the oil pickup.
  8.  



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Fig. Fig. 1: Exploded view of the oil pickup tube mounting-2.5L engine

  1. Remove the two mounting bolts and remove the oil pump from the engine.
  2.  



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Fig. Fig. 2: Align the oil pump shaft as shown-2.5L engine

To install:
  1. Prime the pump by pouring fresh oil into the pump intake and turning the driveshaft until oil comes out the pressure port. Repeat a few times until no air bubbles are present.
  2.  
  3. Apply sealer (Loctite® 515, or equivalent) to the pump body to block machined surface interface. Lubricate the oil pump and distributor driveshaft.
  4.  
  5. Align the slot so it will be in the same position as when it was removed. If it is not, the distributor will not be timed correctly. Install the pump fully and rotate back and forth to ensure proper positioning between the pump mounting surface and the machined surface of the block.
  6.  
  7. Install the mounting bolts finger-tight and lower the vehicle to confirm proper slot positioning. If the slot is not properly positioned, raise the vehicle and move the gear as required. If the slot is correct, hold the pump firmly against the block and tighten the mounting bolts to 17 ft. lbs. (23 Nm).
  8.  
  9. Clean out the oil pickup or replace as required. Replace the oil pickup O-ring and install the pickup to the pump.
  10.  
  11. Install the oil pan using new gaskets. Lower the vehicle.
  12.  
  13. Install the distributor.
  14.  
  15. Install the dipstick. Fill the engine with the proper amount of oil.
  16.  
  17. Connect the negative battery cable, check the timing and check the oil pressure.
  18.  

3.9L Engine

See Figure 3

  1. Disconnect the negative battery cable.
  2.  
  3. Raise the vehicle and support safely. Drain the oil and remove the oil pan.
  4.  
  5. Remove the screen.
  6.  



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Fig. Fig. 3: Remove the screen, then unbolt the oil pump and remove it from the engine

  1. Unbolt the oil pump from the rear main bearing cap and remove it from the vehicle.
  2.  

To install:
  1. Prime the pump by pouring fresh oil into the pump intake and turning the driveshaft until oil comes out the pressure port. Repeat a few times until no air bubbles are present. Install the oil pump with a rotating motion to ensure proper pump driveshaft engagement.
  2.  
  3. Hold the pump flush against the main cap and finger-tighten the attaching bolts.
  4.  
  5. Tighten the bolts to 130 ft. lbs. (176 Nm).
  6.  
  7. Install the screen.
  8.  
  9. Install the oil pan with a new gasket.
  10.  
  11. Connect the negative battery cable and check the oil pressure.
  12.  

5.2L and 5.9L Engines

It is necessary to remove the oil pan, and to remove the oil pump from the rear main bearing cap to service the oil pump.

  1. Drain the engine oil and remove the oil pan.
  2.  
  3. Remove the oil pump mounting bolts and remove the oil pump from the rear main bearing cap.
  4.  

To install:
  1. Install the pump and tighten the cover bolts to 95 inch lbs. (11 Nm).
  2.  
  3. Prime the oil pump before installation by filling the rotor cavity with engine oil. Install the oil pump on the engine and tighten attaching bolts to 30 ft. lbs. (41 Nm).
  4.  
  5. Install the oil pan.
  6.  
  7. Fill the engine with the proper grade motor oil. Start the engine and check for leaks.
  8.  

8.0L Engine

See Figure 4

  1. Remove the timing chain cover.
  2.  
  3. Remove the relief valve plug, gasket, spring and the valve. Discard the gasket.
  4.  
  5. Remove the oil pump cover.
  6.  
  7. Remove the pump rotors.
  8.  

To install:
  1. Install the oil pump and lubricate the pump rotors with petroleum jelly or Lubriplate®.
  2.  
  3. Install the timing chain cover.
  4.  
  5. Position the oil pump cover onto the timing chain cover and tighten the cover bolts to 125 inch lbs. (14 Nm).
  6.  



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Fig. Fig. 4: Lubricate the rotors as a means of priming the oil pump so it is not dry on start-up-V10 engine

  1. After the cover is installed, make sure that the inner ring can still move freely and does not bind in any way.
  2.  
  3. Install the timing chain cover. Squirt oil into the relief valve hole until oil runs out.
  4.  
  5. Using a new pressure relief valve gasket, install the relief valve plug, tightening it to 15 ft. lbs. (20 Nm).
  6.  
  7. Fill the oil filter with oil and install it on the engine.
  8.  

Diesel Engine

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the drive belt.
  4.  
  5. Remove the radiator.
  6.  
  7. Remove the fan assembly.
  8.  
  9. Remove the oil fill tube and adaptor.
  10.  
  11. Remove the crankshaft pulley.
  12.  
  13. Remove the front cover.
  14.  
  15. Remove the four pump mounting bolts and remove the pump from the block.
  16.  

To install:
  1. Prime the pump by pouring fresh oil into the pump intake and turning the driveshaft until oil comes out the pressure port. Repeat a few times until no air bubbles are present.
  2.  
  3. Align the idler gear pin with the locating bore in the block and install the pump.
  4.  
  5. Tighten the mounting bolts in the proper sequence to 44 inch lbs. (5 Nm), then repeat the torquing sequence to 18 ft. lbs. (24 Nm).
  6.  

When the pump is correctly installed, the flange on the pump should not touch the block; the back plate on the pump seats against the bottom of the bore.

  1. Measure the backlash of the idler to pump drive gears. The specification is 0.003-0.013 in. (0.08-0.33mm).
  2.  
  3. Measure the backlash of the idler to crankshaft gears. The specification is 0.003-0.013 in. (0.08-0.33mm).
  4.  
  5. Install the front covert and crankshaft pulley.
  6.  
  7. Install the oil fill tube and adaptor.
  8.  
  9. Install the fan assembly, radiator and drive belt.
  10.  
  11. Connect the negative battery cable and check the oil pressure.
  12.  

INSPECTION & OVERHAUL



2.5L Engine

See Figures 5, 6, 7, 8, 9, 10 and 11

  1. Remove the cover from the oil pump.
  2.  
  3. Check end-play of the inner rotor using a feeler gauge and a straightedge placed across the pump body. The specification is 0.001-0.004 in. (0.03-0.09mm).
  4.  
  5. Measure the clearance between the inner and outer rotors. The maximum clearance is 0.008 in. (0.20mm).
  6.  



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Fig. Fig. 5: Use a caliper to measure the outer rotor thickness

  1. Measure the clearance between the outer rotor and the pump body. The maximum clearance is 0.014 in. (0.35mm).
  2.  



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Fig. Fig. 6: Measure the inner rotor thickness and compare to specifications



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Fig. Fig. 7: Check the oil pump cover for warpage as shown



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Fig. Fig. 8: Use a feeler gauge to check the outer rotor clearance in the housing

  1. The minimum thickness of the outer rotor is 0.944 in. (23.96mm). The minimum diameter of the outer rotor is 2.77 in. (62.70mm). The minimum thickness of the inner rotor is 0.943 in. (23.98mm).
  2.  



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Fig. Fig. 9: Use a feeler gauge to check rotor clearance



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Fig. Fig. 10: Check the rotor-to-cover clearance as shown

  1. Check the cover for warpage. The maximum allowable is 0.003 in. (0.076mm).
  2.  
  3. Check the pressure relief valve for damage. The spring's free-length specification is 1.95 in. (49.50mm).
  4.  



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Fig. Fig. 11: Exploded view of the oil pressure relief valve-2.5L engine

  1. Assemble the outer rotor with the larger chamfered edge in the pump body. Tighten the cover screws to 10 ft. lbs. (12 Nm).
  2.  

3.9L Engine

See Figures 5, 6, 7, 8, 9, 10, 12, 13 and 14

  1. Disassemble the pump.
  2.  
  3. Replace the pump assembly if the cover is scratched or grooved or if the cover is warped more than 0.0015 in. (0.038mm).
  4.  
  5. The minimum thickness of the outer rotor is 0.825 in. (20.96mm). The minimum diameter of the outer rotor is 2.469 in. (62.70mm). The minimum thickness of the inner rotor is 0.825 in. (20.96mm). If any of the above measurements are not within specifications, replace the shaft and both rotors.
  6.  



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Fig. Fig. 12: Exploded view of the V6 engine oil pump

  1. The maximum clearance between the outer rotor and the pump body is 0.014 in (0.356mm). Replace the pump assembly if not within specifications.
  2.  
  3. Install the inner rotor and place a straightedge across the bolt holes. If a feeler gauge of 0.004 in. (0.101mm) or more fits, replace the pump assembly.
  4.  
  5. The maximum clearance between the rotors is 0.010 in. (0.254mm). Replace the shaft and both rotors if not within specifications.
  6.  



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Fig. Fig. 13: Exploded view of the oil pressure relief valve-V6 and V8 engines



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Fig. Fig. 14: Retainer cap installation-V6 and V8 engines

  1. Inspect the relief valve plunger for scoring. Small marks may be removed with 400 grit wet or dry sandpaper.
  2.  
  3. The relief valve spring should have a free length of about 2 in. (50mm). Replace the spring if it fails to meet specifications.
  4.  
  5. Assemble the pump using new parts where necessary.
  6.  

5.2L and 5.9L Engine

See Figures 5, 6, 7, 8, 9, 10, 13 and 14

  1. Remove the relief valve by drilling a 1/8 in. (3mm) hole into the relief valve retainer cap and insert a self-threading sheet metal screw into the cap. Clamp the screw into a vise and while supporting the oil pump, remove the cap by tapping the pump body with a soft hammer. Discard the retainer cap and remove the spring and the relief valve.
  2.  
  3. Remove the oil pump cover and lockwashers, and lift off the cover. Discard the oil ring seal. Remove the pump rotor and shaft, and lift out the outer rotor.
  4.  

Wash all parts in solvent and inspect for damage or wear. The mating surfaces of the oil pump cover should be smooth. Replace the pump assembly if this is not the case.

  1. Lay a straightedge across the pump cover surface and if a 0.0015 in. (0.038mm) feeler gauge can be inserted between the cover and the straightedge, the pump assembly should be replaced. Measure the thickness and the diameter of the outer rotor. If the outer rotor thickness measures 0.825 in. (21mm) or less on 5.2L engines, or 0.943 in (24mm) or less on 5.9L engines, or if the diameter is 2.469 in. (62.7mm) or less, replace the outer rotor. If the inner rotor measures 0.825 in. (21mm) or less on 5.2L engines, or 0.943 in (0.24mm) or less on 5.9L engines, then the inner rotor and shaft assembly must be replaced.
  2.  
  3. Slide the outer rotor into the pump body, do this by pressing it to one side with your fingers and measure the clearance between the rotor and the pump body. If the measurement is 0.014 in (0.355mm) or more, replace the oil pump assembly. Install the inner rotor and shaft into the pump body. If the clearance between the inner and outer rotors is 0.010 in. (0.25mm) or more, replace the soft and both rotors.
  4.  
  5. Place a straightedge across the face of he pump, between the bolt holes. If a feeler gauge of 0.004 in. (0.10mm) or more can be inserted between the rotors and the straightedge, replace the pump assembly.
  6.  
  7. Inspect the oil pressure relief valve plunger for scoring and free operation in its bore. Small marks may be removed with 400-grit wet or dry sandpaper.
  8.  
  9. The relief valve spring has a free length of 2 1 / 32 -2 3 / 64 in. (51.5-52.0mm) and should test between 16.2 and 17.2 lbs. (72-76 N) when compressed to 1 1 /1 32 in. (34mm). Replace the spring if it fails to meet this specification.
  10.  

8.0L Engine

See Figures 15, 16, 17, 18 and 19

Wash all parts in solvent and inspect for damage or wear. The mating surfaces of the oil pump cover should be smooth. Replace the pump assembly if this is not the case.



Click image to see an enlarged view

Fig. Fig. 15: Exploded view of the oil pressure relief valve-V10 engine

  1. Lay a straightedge across the pump cover surface and if a 0.003 in. (0.076mm) feeler gauge can be inserted between the cover and the straightedge, the pump assembly should be replaced. Measure the thickness and the diameter of the outer rotor. If the outer rotor thickness measures 0.744 in. (18.92mm) or less, or if the diameter is 3.246 in. (82.45mm) or less, replace the rotor set.
  2.  



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Fig. Fig. 16: Exploded view of the oil pump assembly-V10 engine

  1. Slide the outer rotor into the timing chain cover pump body, do this by pressing it to one side with your fingers and measure the clearance between the rotor and the pump body. If the measurement is 0.007 in. (0.19mm) or more, and the outer rotor is within specifications, replace the timing chain cover.
  2.  



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Fig. Fig. 17: Use a straightedge and the correct feeler gauge to inspect the oil pump cover for flatness-V10 engine

  1. Install the inner rotor and shaft into the timing chain cover. The inner rotor should have the chamfer up or towards the engine when the cover is installed to allow easy installation over the crankshaft. If the clearance between the inner and outer rotors is 0.006 in. (0.150mm) or more, replace both rotors.
  2.  



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Fig. Fig. 18: Use the specified feeler gauge to closely inspect the outer rotor clearance in the cover-V10 engine

  1. Place a straightedge across the face of the timing chain cover pump body, between the bolt holes. If a feeler gauge of 0.003 in. (0.077mm) or more can be inserted between the rotors and the straightedge, and the rotors are within specifications, replace the timing chain cover.
  2.  



Click image to see an enlarged view

Fig. Fig. 19: Measure the clearance over the rotors with a straightedge and feeler gauge

  1. Inspect the oil pressure relief valve plunger for scoring and free operation in its bore. Small marks may be removed with 400-grit wet or dry sandpaper.
  2.  
  3. The relief valve spring has a free length of approximately 1.95 in. (49.5mm) and should test between 22.5-24.5 lbs. (100-109 N) when compressed to 1 11 / 32 in. (34mm). Replace the spring if it fails to meet this specification.
  4.  

If engine pressure was low and the pump is within specifications, inspect for worn engine bearings or other reasons for oil pressure loss.

 
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