GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Guide

Oil Pan

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Pan removal is possible with the engine in the vehicle on some of the powertrain combinations covered by this guide. If it is possible, it will often require the removal or repositioning of components including, the steering linkage assembly, the forward drive axle and crossmember (4WD) and/or the engine mounts. It is a difficult and tedious task to remove the oil pan with the engine in the vehicle. The chances of contaminating the bearing surfaces or damaging other internal engine components is great. Also, working under the vehicle with the engine jacked up in the frame puts you at great risk for great personal injury. Therefore, it is desirable in most cases to remove the engine in order to gain access to the oil pan.

REMOVAL & INSTALLATION



1.9L Engine

See Figures 1 and 2

  1. Remove the engine from the vehicle.
  2.  
  3. Remove the bolts and nuts attaching the oil pan to the cylinder block, then remove the oil pan.
  4.  
  5. Remove the oil level gage guide tube from the intake manifold and the oil pan.
  6.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that the sealing surfaces on the pan, cylinder block and front cover are clean and free of oil.
  2.  
  3. Apply a thin coat of Permatex® number 2 or equivalent sealer to the front and rear pan-to-block sealing areas (shown in the illustration).
  4.  
  5. Install the new oil pan gasket, aligning the holes, and then install the oil pan.
  6.  
  7. Install and tighten the bolts and nuts evenly to 4 ft. lbs. (5 Nm).
  8.  
  9. Check the edge of the gasket to make certain the gasket is set in position correctly. If the projection of the gasket edge is beyond the oil pan flange is uneven, remove and reinstall.
  10.  
  11. Install the engine into the vehicle. Refill the crankcase with fresh oil. Start the engine, establish normal operating temperatures and check for leaks.
  12.  



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Fig. Fig. 1: Oil pan sealer location-1.9L engine



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Fig. Fig. 2: Oil pan gasket projection

2.0L Engine
2-WHEEL DRIVE

See Figure 3

  1. Remove the engine from the vehicle.
  2.  
  3. Loosen the retainers, then remove the oil pan from the block.
  4.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  2.  
  3. Apply a thin coat of RTV sealant to both ends of a new rear oil pan seal. Sealant must not extend beyond the tabs of the seal. Then install the seal firmly into the rear main bearing cap.
  4.  
  5. Apply a continuous 1 / 8 in. bead of RTV sealant on the oil pan side rails. This bead must be in line with the bolt holes and circled inboard at each hole location.
  6.  

DO NOT apply sealant to the rear oil pan seal mating surface.

  1. Apply RTV sealant to the oil pan surface which fits to the engine front cover. Ensure the sealant meets both side rail beads.
  2.  
  3. Using care to avoid disturbing the RTV beads, install the oil pan onto the cylinder block. The sealant must be wet during oil pan bolt torquing.
  4.  
  5. Install and finger-tighten the oil pan retainers, then torque the attaching bolts to specification:

    Oil pan-to-cover: 6-9 ft. lbs. (8-12 Nm)
     
    Oil pan-to-side rail: 4-9 ft. lbs. (5-12 Nm)
     
    Oil pan-to-rear holes: 11-17 ft. lbs. (15-23 Nm)
     

  6.  
  7. Install the engine into the vehicle. Refill the crankcase with fresh oil. Start the engine, establish normal operating temperatures and check for leaks.
  8.  



Click image to see an enlarged view

Fig. Fig. 3: Oil pan mounting-2.0L engine

4-WHEEL DRIVE
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the starter front brace bolt.
  4.  
  5. Remove the motor mount through-bolts.
  6.  
  7. Raise and support the front of the vehicle safely using jackstands.
  8.  
  9. Remove the front splash shield, and the brake and fuel line clip retaining bolts.
  10.  
  11. Remove the crossmember bolts and crossmember. Rotate the crossmember around the lines.
  12.  
  13. Drain the engine oil.
  14.  
  15. Remove the starter bolts and support the starter aside using mechanic's wire.
  16.  
  17. Disconnect the steering damper at the frame.
  18.  
  19. Scribe the idler arm location and disconnect the idler arm and steering gear at the frame. Disconnect the front axle at the frame.
  20.  
  21. Disconnect the front driveshaft at the front differential, then slide the differential forward.
  22.  
  23. Remove the oil pan bolts.
  24.  
  25. Raise the engine slightly, as necessary, then remove the pan.
  26.  

Raising the engine too far could damage the EGR system. Watch for contact between the cowl and engine mounted components.

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  2.  
  3. Apply a thin coat of RTV sealant to both ends of a new rear oil pan seal. Sealant must not extend beyond the tabs of the seal. Then install the seal firmly into the rear main bearing cap.
  4.  
  5. Apply a continuous 1 / 8 in. bead of RTV sealant on the oil pan side rails. This bead must be in line with the bolt holes and circled inboard at each hole location.
  6.  

DO NOT apply sealant to the rear oil pan seal mating surface.

  1. Apply RTV sealant to the oil pan surface which fits to the engine front cover. Ensure the sealant meets both side rail beads.
  2.  
  3. Using care to avoid disturbing the RTV beads, install the oil pan onto the cylinder block. The sealant must be wet during oil pan bolt torquing.
  4.  
  5. Install and finger-tighten the oil pan retainers, then torque the attaching bolts to specification:

    Oil pan-to-cover: 6-9 ft. lbs. (8-12 Nm)
     
    Oil pan-to-side rail: 4-9 ft. lbs. (5-12 Nm)
     
    Oil pan-to-rear holes: 11-17 ft. lbs. (15-23 Nm)
     

  6.  
  7. Reposition the differential, then connect the front driveshaft and connect the front drive axle at the frame.
  8.  
  9. Align the matchmarks made earlier, then connect the idler arm and steering gear at the frame.
  10.  
  11. Connect the steering damper to the frame.
  12.  
  13. Install the starter and secure using the retaining bolts.
  14.  
  15. Install the crossmember. Be careful when rotating the crossmember around the lines.
  16.  
  17. Install the brake and fuel line clip retaining bolts, then install the front splash shield.
  18.  
  19. Remove the jackstands and carefully lower the front of the truck.
  20.  
  21. Install the motor mount through-bolts.
  22.  
  23. Install the starter front brace bolt.
  24.  
  25. Refill the crankcase with fresh oil, then connect the negative battery cable. Start the engine, establish normal operating temperatures and check for leaks.
  26.  

2.2L Diesel Engine

See Figure 4

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the front of the vehicle safely using jackstands.
  4.  
  5. Drain the engine oil.
  6.  
  7. Remove the oil pan bolts and remove the pan.
  8.  
  9. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  10.  
  11. Installation is the reverse of removal. Tighten bolts to 2-4 ft. lbs.(3-5 Nm).
  12.  
  13. Refill the crankcase with fresh oil. Start the engine, establish normal operating temperatures and check for leaks.
  14.  



Click image to see an enlarged view

Fig. Fig. 4: Oil pan mounting-2.2L diesel engine

2.5L Engine

See Figure 5

2-WHEEL DRIVE
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the power steering reservoir at the fan shroud.
  4.  
  5. Remove the radiator fan shroud.
  6.  
  7. Raise and support the front of the vehicle safely using jackstands.
  8.  
  9. Drain the engine oil.
  10.  
  11. Remove the strut rods.
  12.  
  13. Disconnect the exhaust pipes at the manifolds.
  14.  
  15. Remove the catalytic converter and exhaust pipe.
  16.  
  17. Remove the flywheel cover.
  18.  
  19. Remove the starter and brace.
  20.  
  21. Remove the brake line at the crossmember. Remove the engine mount through-bolts.
  22.  
  23. Carefully raise the engine, as necessary for clearance, then remove the oil pan bolts and pan.
  24.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  2.  
  3. Apply RTV sealant to the oil pan flange and block as shown in the illustration.
  4.  
  5. Using care to avoid disturbing the RTV beads, install the oil pan onto the cylinder block. The sealant must be wet during oil pan bolt torquing.
  6.  
  7. Tighten oil pan bolts to 90 inch lbs. (10 Nm).
  8.  
  9. Carefully lower the engine into position, then install and tighten the mount through-bolts.
  10.  
  11. Install the brake line to the crossmember.
  12.  
  13. Install the starter and brace.
  14.  
  15. Install the flywheel cover.
  16.  
  17. Install the converter and exhaust pipe, then connect the exhaust pipe to the manifolds.
  18.  
  19. Install the strut rods, then remove the jackstands and lower the vehicle.
  20.  
  21. Install the radiator/fan shroud, then install the power steering reservoir.
  22.  
  23. Refill the engine crankcase, then connect the negative battery cable.
  24.  
  25. Start the engine, establish normal operating temperatures and check for leaks.
  26.  



Click image to see an enlarged view

Fig. Fig. 5: Applying RTV sealant to the oil pan and block-2.5L gasoline engine

4-WHEEL DRIVE
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the power steering reservoir at the fan shroud.
  4.  
  5. Remove the radiator fan shroud.
  6.  
  7. Remove the engine oil dipstick.
  8.  
  9. Raise and support the front of the vehicle safely using jackstands.
  10.  
  11. Drain the engine oil.
  12.  
  13. Remove the brake line at the crossmember, then remove the crossmember.
  14.  
  15. If equipped, remove the transmission cooler lines.
  16.  
  17. Disconnect the exhaust pipes at the manifolds.
  18.  
  19. Remove the catalytic converter hanger.
  20.  
  21. Remove the flywheel cover.
  22.  
  23. Remove the driveshaft splash shield.
  24.  
  25. Matchmark and remove the idler arm assembly.
  26.  
  27. Remove the steering gear bolts. Pull the steering gear and linkage forward.
  28.  
  29. Remove the differential housing mounting bolts at the bracket on the right side and at the frame on the left side.
  30.  
  31. Remove the starter and brace.
  32.  
  33. Remove the engine mount through-bolts.
  34.  
  35. Remove the oil pan bolts and pan.
  36.  

To install:
  1. Apply RTV sealant to the oil pan flange and block as shown in the illustration.
  2.  
  3. Using care to avoid disturbing the RTV beads, install the oil pan onto the cylinder block. The sealant must be wet during oil pan bolt torquing.
  4.  
  5. Tighten oil pan bolts to 90 inch lbs. (10 Nm).
  6.  
  7. Install the engine mount through-bolts.
  8.  
  9. Install the starter and brace.
  10.  
  11. Install the differential housing mounting bolts at the bracket on the right side and at the frame on the left side.
  12.  
  13. Reposition the steering gear and linkage, then install the steering gear bolts.
  14.  
  15. Align and secure the idler arm assembly.
  16.  
  17. Install the driveshaft splash shield.
  18.  
  19. Install the flywheel cover.
  20.  
  21. Install the catalytic converter hanger.
  22.  
  23. Connect the exhaust pipes at the manifolds.
  24.  
  25. If equipped, connect the transmission cooler lines.
  26.  
  27. Install the crossmember, then secure the brake line at the crossmember.
  28.  
  29. Remove the jackstands and carefully lower the vehicle.
  30.  
  31. Install the engine oil dipstick.
  32.  
  33. Install the radiator fan shroud.
  34.  
  35. Install the power steering reservoir at the fan shroud.
  36.  
  37. Refill the engine crankcase, then connect the negative battery cable.
  38.  
  39. Start the engine, establish normal operating temperatures and check for leaks.
  40.  

2.8L and 4.3L Engine
2-WHEEL DRIVE
  1. Remove the engine from the vehicle.
  2.  
  3. Remove the oil pan retainers (nuts, studs and/or bolts) and rail reinforcements, if equipped. Remove the oil pan from the block.
  4.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  2.  
  3. Apply 1052080 (4.3L), 1052914 (2.8L) or an equivalent sealant to the oil pan rail where it contacts the timing cover-to-block joint (front) and the crankshaft rear seal retainer-to-block joint (rear). Continue the bead of sealant about 1 in. (25mm) in both directions from each of the four corners.
  4.  

For the 2.8L engine, be sure all RTV is removed from the blind attaching holes to ensure proper fastener tightening can take place.

  1. Using a new gasket, install the oil pan, reinforcements (if equipped) and retainers. Tighten the retainers to specification:
    1. For 2.8L engines:

      Two rear bolts (through 1992) and all bolts (1993): 18 ft. lbs. (25 Nm).
       
      All other bolts (through 1992), studs and nuts: 7 ft. lbs. (10 Nm)
       
      For 4.3L engine:
       
      Bolts: 100 inch lbs. (11 Nm).
       
      Nuts at corners: 17 ft. lbs. (23 Nm)
       

    2.  

  2.  
  3. Install the engine into the vehicle. Refill the crankcase with fresh oil. Start the engine, establish normal operating temperatures and check for leaks.
  4.  

4-WHEEL DRIVE VEHICLES THROUGH 1991

See Figures 6 through 22



Click image to see an enlarged view

Fig. Fig. 6: Loosen the brake line bracket-to-crossmember retaining bolts



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Fig. Fig. 7: Reposition the brake line away from the crossmember taking care not to damage the line



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Fig. Fig. 8: Loosen and remove the crossmember bolts



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Fig. Fig. 9: Begin lowering the crossmember from the vehicle, being careful not to snag the brake line



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Fig. Fig. 10: Once the crossmember is clear of the brake line, remove it from the vehicle



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Fig. Fig. 11: Loosen and remove the flywheel cover retaining bolts



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Fig. Fig. 12: With the bolts removed, carefully lower the flywheel cover from the vehicle



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Fig. Fig. 13: Disengage the steering shock (steering damper) from the frame bracket



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Fig. Fig. 14: Scribe the alignment of the idle arm bracket to the frame



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Fig. Fig. 15: Loosen the idler arm to to frame retainers (a backup wrench will be necessary for this)



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Fig. Fig. 16: Separate the idler arm bracket from the frame



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Fig. Fig. 17: Loosen and remove the steering gear retainers



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Fig. Fig. 18: Loosen and remove the front differential axle tube bracket retainers



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Fig. Fig. 19: Remove the remaining front differential bracket retainers and the motor mount through bolts



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Fig. Fig. 20: Loosen and remove the oil pan bolts



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Fig. Fig. 21: Carefully lower the oil pan from the engine block



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Fig. Fig. 22: BE CAREFUL, with the pan removed, the crank, oil pump and bearings are exposed to dirt or damage

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the dipstick.
  4.  
  5. Raise and support the front of the vehicle safely using jackstands.
  6.  
  7. Remove the drive belt splash pan, the front axle shield and the transfer case shield, as equipped.
  8.  
  9. If necessary on early carbureted vehicles, disconnect the fuel lines and plug the openings.
  10.  
  11. Remove the brake line clips from the crossmember and the 2nd crossmember from the vehicle.
  12.  
  13. If equipped with an A/T, remove the converter hanger bolt, then disconnect the exhaust pipes at manifold and clamp from the catalytic converter. Slide the exhaust rearward.
  14.  
  15. Remove the front driveshaft-to-drive pinion nuts/bolts.
  16.  
  17. If equipped, disconnect the engine braces at the flywheel cover and loosen the braces at the block.
  18.  
  19. Remove the flywheel cover.
  20.  
  21. Remove starter-to-engine bolts, then remove the starter or support the starter aside using mechanic's wire.
  22.  
  23. Remove the steering shock absorber from the frame bracket. Using a scribing tool, mark the position of the idler arm-to-chassis, then remove the steering gear-to-chassis bolts along with the idler arm-to-chassis bolts. Slide the steering gear and linkage forward for clearance.
  24.  

A deeply offset wrench may be necessary to hold the differential housing nut. If the wrench cannot be fit fully over the nut, use a prybar to hold the wrench in position while the bolt is broken loose.

  1. Remove the front differential-to-bracket bolts from the sides of the chassis, then pull the front differential housing forward for clearance.
  2.  
  3. Remove the motor mount through-bolts.
  4.  
  5. Drain the engine oil.
  6.  

Use extreme caution when blocking the engine in position. Get out from underneath the truck and rock the engine slightly once the blocks are in place to be sure the engine is properly supported.

  1. Raise the engine slightly and block in position for safety.
  2.  
  3. Remove the oil pan-to-engine bolts, then remove the oil pan from the engine.
  4.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  2.  

The oil pans on some early 2.8L engines may have been installed with no gasket, only RTV sealant. If a gasket is available during installation, it should be used. If not, use a3/8in. bead of RTV sealant around the entire oil pan sealing flange.

  1. If a gasket is available, apply 1052080 (4.3L), 1052914 (2.8L) or an equivalent sealant to the oil pan rail where it contacts the timing cover-to-block joint (front) and the crankshaft rear seal retainer-to-block joint (rear). Continue the bead of sealant about 1 in. (25mm) in both directions from each of the four corners.
  2.  

For the 2.8L engine, be sure all RTV is removed from the blind attaching holes to ensure proper fastener tightening can take place.

  1. Using a new gasket, install the oil pan, reinforcements (if equipped) and retainers. Tighten the retainers to specification:
    1. For 2.8L engines:

      Two rear bolts: 18 ft. lbs. (25 Nm).
       
      All other bolts, studs and nuts: 7 ft. lbs. (10 Nm)
       
      For 4.3L engine:
       
      Bolts: 100 inch lbs. (11 Nm).
       
      Nuts at corners: 17 ft. lbs. (23 Nm)
       

    2.  

  2.  
  3. Remove the blocks and carefully lower the engine into position, then install the motor mount through-bolts.
  4.  
  5. Reposition the differential housing, then install the retaining bolts.
  6.  
  7. Reposition the steering linkage and align the marks made earlier, then install and tighten the retainers.
  8.  
  9. Install the steering shock absorber to the frame bracket.
  10.  
  11. Reposition and secure the starter motor, then install the flywheel cover.
  12.  
  13. If equipped, connect the engine braces at the flywheel cover and secure the braces at the block.
  14.  
  15. Connect the front driveshaft to the drive pinion.
  16.  
  17. If applicable, connect the exhaust pipes to the manifold, then install the converter hanger bolts and the exhaust pipe clamp.
  18.  
  19. Install the second crossmember to the vehicle, then secure the brake line clips at the crossmember.
  20.  
  21. If disengage, remove the plugs then reconnect the fuel lines.
  22.  
  23. As applicable, install the transfer case shield, front axle shield and/or drive belt splash shield.
  24.  
  25. Install the dipstick, then remove the jackstands and carefully lower the vehicle.
  26.  
  27. Refill the crankcase with fresh oil, then connect the negative battery cable.
  28.  
  29. Start the engine, establish normal operating temperatures and check for leaks.
  30.  

4-WHEEL DRIVE VEHICLES 1992-1993
  1. Disconnect the negative battery cable.
  2.  
  3. Remove the dipstick.
  4.  
  5. Raise and support the front of the vehicle safely using jackstands.
  6.  
  7. Remove the drive belt splash shield, the front axle shield, and the transfer case shield.
  8.  
  9. Remove the front skid plate and drain the engine crankcase oil, then remove the flywheel cover.
  10.  
  11. Remove the left and right motor mount through-bolts.
  12.  
  13. Raise the engine using a suitable lifting device and block in position. This may be accomplished using large wooden blocks between the motor mounts and brackets.
  14.  

Use extreme caution when blocking the engine in position. Get out from underneath the truck and rock the engine slightly once the blocks are in place to be sure the engine is properly supported.

  1. Disconnect the oil cooler line, then remove the oil filter adapter.
  2.  
  3. Remove the pitman arm bolt, then disconnect the pitman arm.
  4.  
  5. Remove the idler arm bolts, then disconnect the idler arm.
  6.  
  7. Remove the front differential through-bolts, then disconnect or remove the front driveshaft (as necessary).
  8.  
  9. Roll the differential assembly forward for clearance.
  10.  
  11. Remove the starter motor retaining bolts, then lower the starter and either remove it from the vehicle or suspend it out of the way using mechanic's wire.
  12.  
  13. Remove the oil pan bolts, nuts and reinforcements, then lower the oil pan and gasket from the vehicle.
  14.  

To install:
  1. Using a putty knife, clean the gasket mounting surfaces. Make sure that all sealing surfaces are clean and free of oil.
  2.  
  3. Apply 1052080, or an equivalent sealant to the oil pan rail where it contacts the timing cover-to-block joint (front) and the crankshaft rear seal retainer-to-block joint (rear). Continue the bead of sealant about 1 in. (25mm) in both directions from each of the four corners.
  4.  
  5. Using a new gasket, install the oil pan, reinforcements and retainers. Tighten the bolts to 100 inch lbs. (11 Nm) and the nuts at the corners to 17 ft. lbs. (23 Nm).
  6.  
  7. Install the starter motor and secure using the mounting bolts.
  8.  
  9. Roll the differential back into position, then install/connect the front driveshaft. Install the front differential through-bolts.
  10.  
  11. Connect the idler arm and secure using the retaining bolts, then connect the pitman arm and secure using the bolts.
  12.  
  13. Install the transfer case shield.
  14.  
  15. Install the flywheel cover, then install the front skid plate.
  16.  
  17. Install the front axle shield, then install the drive belt splash shield.
  18.  
  19. Remove the jackstands and carefully lower the truck.
  20.  
  21. Install the dipstick, then properly refill the engine crankcase.
  22.  
  23. Connect the negative battery cable.
  24.  
  25. Start the engine, establish normal operating temperatures and check for leaks.
  26.  

 
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