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

Timing (Front) Cover

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On most vehicles it is possible to replace the timing cover front seal without removing the timing cover. For details, please refer to the procedures found later in this section.

REMOVAL & INSTALLATION



1.9L Engine
  1. Remove the cylinder head. Please refer to the procedures located earlier in this section for details.
  2.  
  3. Remove the oil pan. Please refer to the procedures located earlier in this section for details.
  4.  
  5. Remove the oil pickup tube from the oil pump.
  6.  
  7. Remove the crankshaft hub and pulley.
  8.  
  9. If not done already, remove the AIR pump drive belt.
  10.  
  11. If equipped with air conditioning, remove the compressor and mounting brackets and position aside with the lines intact. DO NOT disconnect the refrigerant lines.
  12.  
  13. Matchmark and remove the distributor assembly.
  14.  
  15. Remove the front cover attaching bolts, then remove the front cover.
  16.  
  17. If the crankshaft oil seal shows signs of wear or damage, carefully pry it from the cover using a suitable prytool.
  18.  

To install:
  1. If removed, install a new oil seal to the front cover using J-26587, or an equivalent seal driver tool. Be sure to support the rear of front cover in the seal area.
  2.  
  3. Check the front cover inner and outer faces for cracking or damage. Replace as necessary.
  4.  
  5. Install a new gasket onto the engine.
  6.  
  7. Align the oil pump drive gear punch mark with the oil filter side of cover; then align the center of dowel pin with alignment mark on the oil pump case.
  8.  
  9. Rotate the crankshaft until the No. 1 and No. 4 cylinders are at TDC of the compression stroke.
  10.  
  11. Install the front cover by engaging the pinion gear with the oil pump drive gear on the crankshaft. Loosely secure the cover using the retainers.
  12.  
  13. Check that the punch mark on the oil pump drive gear is turned to the rear side as viewed through clearance between front cover and cylinder block.
  14.  
  15. Check that the slit at the end of the oil pump shaft is parallel with front face of cylinder block and that it is offset forward.
  16.  
  17. Once the cover and oil pump components are verified as properly aligned, tighten the front cover retainers.
  18.  
  19. Align and install the distributor.
  20.  
  21. Install the crankshaft hub and pulley, then install the accessory drive belts.
  22.  
  23. Install the oil pickup tube to the pump.
  24.  
  25. Install the oil pan.
  26.  
  27. Install the cylinder head.
  28.  
  29. Refill the engine crankcase, then connect the negative battery cable.
  30.  
  31. Check and/or adjust the engine timing. Inspect for leaks.
  32.  

2.0L Engine

See Figure 1

  1. Disconnect the negative battery cable, then drain the engine cooling system.
  2.  
  3. Remove the upper fan shroud.
  4.  
  5. Loosen the accessory drive belt adjusters and remove the drive belts from the crankshaft pulley.
  6.  
  7. Remove the cooling fan-to-water pump bolts and the pulley.
  8.  
  9. Disconnect the radiator hose and the heater hose from the water pump. Remove the water pump-to-engine bolts and the water pump from the engine.
  10.  
  11. Remove the pulley and hub from the end of the crankshaft.
  12.  
  13. Remove the front cover-to-engine bolts, then remove the cover from the engine.
  14.  
  15. If the crankshaft oil seal shows signs of wear or damage, carefully pry it from the cover using a suitable prytool.
  16.  

To install:
  1. If removed, install a new oil seal to the front cover using J-23042, or an equivalent seal driver tool. Be sure to support the rear of front cover in the seal area.
  2.  
  3. Using a putty knife, clean the gasket mounting surfaces. Using solvent, clean the oil and grease from the gasket mounting surfaces.
  4.  
  5. Apply a 2-3mm bead of RTV sealant to the front cover, oil pan and water pump sealing surfaces.
  6.  

When applying RTV sealant to the front cover, be sure to keep it out of the bolt holes. The sealant must be wet to the touch when the bolts are torqued down.



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Fig. Fig. 1: Crankshaft pulley and hub assembly-2.0L engine

  1. Install the front cover and tighten the retaining bolts.
  2.  
  3. Install the pulley and hub to the end of the crankshaft.
  4.  
  5. Install the water pump, then connect the radiator hose and the heater hose to the water pump.
  6.  
  7. Install the cooling fan pulley and the fan-to-water pump bolts.
  8.  
  9. Install the accessory drive belts and adjust their tension.
  10.  
  11. Install the upper fan shroud.
  12.  
  13. Connect the negative battery cable, then properly refill the engine cooling system.
  14.  

2.2L Diesel Engine

See Figure 2

Unlike the gasoline engines covered by this manual, the 2.2L diesel engine is equipped with a timing belt not a chain or gear assembly. The belt remains dry, therefore the oil seal is not mounted in the timing housing covers, but in the timing pulley housing mounted beneath the cover and the timing pulley assembly. The following procedure covers removal and installation of the timing housing covers. For oil seal or housing service, please refer to the procedure located later in this section.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the power steering reservoir.
  4.  
  5. Remove the upper fan shroud, then remove the fan.
  6.  
  7. Loosen the drive belts and remove the fan drive pulley.
  8.  
  9. Remove the upper cover attaching bolts and remove the upper timing cover.
  10.  
  11. Remove the alternator belt.
  12.  
  13. Align the crankshaft pulley mark to the TDC mark for ease of installation, then remove the attaching bolts. Remove the pulley.
  14.  



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Fig. Fig. 2: Crankshaft pulley alignment-2.2L diesel engine

  1. Remove the lower cover attaching bolts, then remove the lower cover.
  2.  

To install:
  1. Install the lower timing cover and secure using the attaching bolts.
  2.  
  3. Align the crankshaft pulley, then install and secure using the attaching bolts.
  4.  
  5. Install the alternator belt.
  6.  
  7. Install the upper cover and secure using the attaching bolts.
  8.  
  9. Install the fan drive pulley, then install and adjust the drive belts.
  10.  
  11. Install the fan, then install the upper fan shroud.
  12.  
  13. Install the power steering reservoir.
  14.  
  15. Connect the negative battery cable.
  16.  

2.5L Engine

See Figures 3 and 4

The following procedure requires the use of the GM Seal Installer/Centering tool No. J-34995 or equivalent.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the power steering reservoir from the fan shroud, then remove the fan shroud.
  4.  
  5. Remove the accessory drive belts or the serpentine drive belt, as applicable.
  6.  
  7. Remove the alternator and brackets from the engine (lay them aside).
  8.  
  9. Remove the crankshaft pulley and hub.
  10.  



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Fig. Fig. 3: Crankshaft pulley and timing cover assembly-2.5L engine

The outer ring (weight) of the torsional damper is bonded to the hub with rubber. The damper must be removed with a puller which acts on the inner hub only. Pulling on the outer portion of the damper will break the rubber bond or destroy the tuning of the unit.

  1. Drain the engine cooling system, then disconnect the lower radiator hose at the water pump.
  2.  
  3. Remove the timing cover bolts and cover. Check for bolts threaded from the front of the oil pan to the bottom of the cover. If present, these must be removed before attempting to loosen the cover.
  4.  
  5. If the front seal is to be replaced, it can be pried out of the cover with a small prytool.
  6.  

To install:
  1. If removed, use the GM seal installer/centering tool J-34995 or equivalent to install the replacement cover seal. Be sure to support the seal area of the cover when installing the new seal.
  2.  
  3. Clean all sealing surfaces and apply a 3 / 8 in. bead of RTV sealant to the oil pan and timing gear cover sealing surfaces.
  4.  
  5. Use the GM Seal Installer/Centering Tool J-34995 or equivalent align the front cover. Install the cover while the RTV sealant is still wet.
  6.  



Click image to see an enlarged view

Fig. Fig. 4: Applying sealer to the timing cover mating surface-2.5L engine

  1. Install the cover (and pan) retaining bolts, then tighten the bolts to 90 inch lbs. (10 Nm). Remove the centering tool from the timing cover.
  2.  
  3. Connect the lower radiator hose to the water pump.
  4.  
  5. Install the crankshaft hub and pulley.
  6.  
  7. Reposition and secure the alternator and brackets.
  8.  
  9. Install the serpentine drive belt or install and adjust the accessory drive belts, as applicable.
  10.  
  11. Install the upper fan shroud, then reposition and secure the power steering reservoir.
  12.  
  13. Connect the negative battery cable and properly refill the engine cooling system.
  14.  
  15. Run the engine until normal operating temperature is reached, then check for leaks.
  16.  

2.8L Engine

See Figures 5 through 14

  1. Disconnect the negative battery cable, then drain the engine cooling system.
  2.  
  3. Remove the accessory drive belts or the serpentine drive belt, as applicable.
  4.  
  5. Remove the water pump from the engine. For details, please refer to the procedure earlier in this section.
  6.  
  7. For early model engines equipped with A/C, remove the compressor from the mounting bracket and position it aside with the lines attached. Be careful not to kink or damage the refrigerant lines.
  8.  
  9. For late model engines, remove the power steering pump bracket.
  10.  
  11. Remove the crankshaft pulley bolt, crankshaft pulley and hub (torsional damper).
  12.  

The outer ring (weight) of the torsional damper is bonded to the hub with rubber. The damper must be removed with a puller which acts on the inner hub only. Pulling on the outer portion of the damper will break the rubber bond or destroy the tuning of the unit.

  1. Disconnect the lower radiator hose at the front cover.
  2.  
  3. Remove the timing cover bolts and cover. Check for bolts threaded from the front of the oil pan to the bottom of the cover. If present, these must be removed before attempting to loosen the cover.
  4.  
  5. If the front seal is to be replaced, it can be pried out of the cover with a small prytool.
  6.  

To install:
  1. Clean the gasket mating surfaces of the engine and cover of all remaining gasket or sealer material. Be careful not to score or damage the surfaces.
  2.  
  3. If removed, install a new seal to the cover using a suitable installation driver such as J-23042 (early model), J-35468 (late model) or equivalent. Be sure to support the back of the seal cover area during installation. Lightly coat the lips of the new seal with clean engine oil.
  4.  
  5. Lightly coat both sides of a new gasket using an anaerobic sealant, then position the gasket and cover to the engine. Install and tighten the retainers. On early model vehicles (or vehicles with a oil pan sealing lip on the cover), apply a bead of sealant to the front cover at the oil pan mating surface.
  6.  

If equipped, don't forget the oil pan-to-front-cover bolts.

  1. Install the water pump assembly to the engine.
  2.  
  3. Connect the lower radiator hose to the front cover.
  4.  
  5. Install the crankshaft hub and pulley.
  6.  
  7. Install the power steering pump bracket or the A/C compressor, as applicable.
  8.  
  9. Install the serpentine drive belt or install and adjust the accessory drive belts, as applicable.
  10.  
  11. Connect the negative battery cable, then properly refill the engine cooling system.
  12.  
  13. Run the engine until normal operating temperature has been reached, then check for leaks.
  14.  



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Fig. Fig. 5: Remove the pulley from the crankshaft hub so a threaded puller may be installed



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Fig. Fig. 6: Use a puller to free the damper hub from the crankshaft



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Fig. Fig. 7: Disconnect the hose from the timing cover



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Fig. Fig. 8: Loosen the timing cover retainers



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Fig. Fig. 9: Remove the cover retainers, note the positions of studs and various length bolts



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Fig. Fig. 10: Check for oil pan-to-front cover bolts and, if present, remove them



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Fig. Fig. 11: Most bolts would be threaded upward from the oil pan to the front cover



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Fig. Fig. 12: Once all of the bolts are removed, break the gasket seal and remove the front cover



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Fig. Fig. 13: Remove all gasket material from the cover's mating surface ...



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Fig. Fig. 14: ... then from the block and, if applicable, oil pan, but DO NOT allow debris to fall in the pan

4.3L Engine
  1. Disconnect the negative battery cable and drain the engine cooling system.
  2.  
  3. Remove the crankshaft pulley and damper. For details, please refer to the procedure earlier in this section.
  4.  

The outer ring (weight) of the torsional damper is bonded to the hub with rubber. The damper must be removed with a puller which acts on the inner hub only. Pulling on the outer portion of the damper will break the rubber bond or destroy the tuning of the unit.

  1. Remove the water pump assembly.
  2.  
  3. For 1988-91 vehicles:
    1. Remove the oil pan from the engine.
    2.  
    3. Disconnect the upper radiator hose
    4.  
    5. If equipped, remove the air conditioner compressor and position it aside with the lines attached. DO NOT disconnect any refrigerant lines but take caution not to kink or otherwise damage them.
    6.  
    7. Remove the right side engine accessory bracket.
    8.  

  4.  
  5. For 1992-93 vehicles, loosen the oil pan.
  6.  
  7. Remove the front cover bolts and, if equipped, the reinforcements, then remove the front cover from the engine.
  8.  
  9. If the front cover seal is to be replaced, it may be pried front the front cover using a suitable prytool.
  10.  

To install:
  1. Clean the gasket mating surfaces of the engine and cover of all remaining gasket or sealer material. Be careful not to score or damage the surfaces.
  2.  

Beginning in 1992, the manufacturer began suggesting you wait until the front cover is mounted to the engine before you install the replacement crankshaft oil seal. This may be to assure the cover is properly supported. On earlier vehicles, the manufacturer allowed for installation with the cover removed or installed, so waiting would be acceptable for all years of the 4.3L engine.

  1. If desired on early model engines, install a new seal to the cover using a suitable installation driver, such as J-35468 or equivalent. Be sure to support the back of the seal cover area during installation. Lightly coat the lips of the new seal with clean engine oil.
  2.  
  3. Position a new front cover gasket to the engine or cover using gasket cement to hold it in position. For 1992-93 vehicles, lubricate the front of the oil pan seal with engine oil to aid in reassembly.
  4.  
  5. Install the front cover to the engine. For 1992-93 vehicles, tale care while engaging the front of the oil pan seal with the bottom of the cover.
  6.  
  7. Install front cover retaining bolts and tighten to 124 inch lbs. (14 Nm).
  8.  
  9. If removed and not installed earlier, use the seal installation driver to install the new crankshaft seal at this time.
  10.  
  11. For 1992-93 vehicles, secure the oil pan.
  12.  
  13. For 1988-91 vehicles:
    1. Install the right side engine accessory bracket.
    2.  
    3. If equipped, reposition and secure the A/C compressor.
    4.  
    5. Install the oil pan.
    6.  

  14.  
  15. Install the water pump.
  16.  
  17. Install the crankshaft damper and pulley.
  18.  
  19. Connect the negative battery cable, then properly refill the engine cooling system.
  20.  
  21. Run the engine until normal operating temperature has been reached, then check for leaks.
  22.  

 
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