GM Full Size Vans 1987-1997 Repair Guide

Camshaft, Bearing and Lifters

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REMOVAL & INSTALLATION



4.3L, 5.0L and 5.7L Engines

See Figures 1 through 5



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Fig. Fig. 1: Camshaft and timing chain - 4.3L engine



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Fig. Fig. 2: Camshaft and related parts - 5.0L, 5.7L, 6.2L, 6.5L and 7.4L engines


CAUTION
Please refer to General Information & Maintenance before discharging the compressor or disconnecting air conditioning lines. Damage to the air conditioning system or personal injury could result. Consult your local laws concerning refrigerant discharge and recycling. In many areas it may be illegal for anyone but a certified technician to service the A/C system. Always use an approved recovery station when discharging the air conditioning.

  1. Disconnect the negative battery cable.
  2.  
  3. On some models it may be necessary to remove the grille and hood assemblies.
  4.  
  5. Remove the air cleaner assembly and if equipped, remove the coolant recovery reservoir.
  6.  

  1. Have the system discharged by a qualified technician using approved equipment.
  2.  
  3. Drain the cooling system then remove the radiator.
  4.  
  5. Remove the air conditioning condenser.
  6.  
  7. Tag and disengage any vacuum lines and electrical connections which will hinder the removal of the camshaft.
  8.  
  9. Mark the distributor as to location in the block. Remove the distributor and spark plugs.
  10.  
  11. Remove the valve covers.
  12.  
  13. Remove the drive belt(s).
  14.  
  15. If necessary remove the alternator and its retaining brackets.
  16.  
  17. Remove the water pump.
  18.  
  19. Remove the engine oil dipstick tube.
  20.  
  21. Remove the valve lifters and pushrods.
  22.  
  23. Remove the crankshaft pulley and damper.
  24.  
  25. Remove the front cover, timing chain and sprockets.
  26.  
  27. Install two 5 / 16 in.-18 bolts in the holes in the front of the camshaft and carefully pull the camshaft from the block.
  28.  



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Fig. Fig. 3: Crankshaft position sensor reluctor ring location - 4.3L, 5.0L and 5.7L engines



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Fig. Fig. 4: Removing the camshaft



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Fig. Fig. 5: Camshaft oil gallery plugs at the rear of the block

To install:
  1. Liberally coat camshaft and bearing with heavy engine oil or engine assembly lubricant and insert the cam into the engine.
  2.  
  3. Install the timing chain.
  4.  
  5. Install the reluctor ring, lifters and pushrods.
  6.  
  7. Install the intake manifold.
  8.  
  9. Install the distributor using the locating marks made during removal. (If any problems are encountered, refer to distributor removal and installation)
  10.  
  11. Install the damper and water pump.
  12.  
  13. Install the valve covers and the cooling fan.
  14.  
  15. Engage all vacuum and electrical connections.
  16.  
  17. Install the radiator and condenser.
  18.  
  19. Fill the cooling system with the right amount and grade of oil.
  20.  
  21. Install coolant recovery reservoir and the air cleaner assembly.
  22.  
  23. Install the engine cover and connect the battery cable.
  24.  

7.4L Engines

See Figures 2, 4, 5 and 6

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Remove the grille.
  6.  
  7. Remove the air conditioning compressor from its brackets and move the compressor out of the way without disconnecting the lines.
  8.  
  9. Drain the cooling system.
  10.  
  11. Remove the fan shroud and radiator.
  12.  
  13. Remove the drive belt(s), loosen the alternator bolts and move the alternator to one side.
  14.  



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Fig. Fig. 6: Crankshaft position sensor reluctor ring location - 7.4L engines

  1. Remove the cylinder head covers.
  2.  
  3. Disconnect the hoses from the water pump.
  4.  
  5. Remove the water pump.
  6.  
  7. Remove the torsional damper and pulley.
  8.  
  9. Remove the front cover.
  10.  
  11. Mark the distributor as to location in the block. Remove the distributor.
  12.  
  13. Remove the intake manifold.
  14.  
  15. Mark the lifters, pushrods, and rocker arms as to location so that they may be installed in the same position. Remove these parts.
  16.  
  17. Rotate the camshaft so that the timing marks align.
  18.  
  19. Remove the camshaft sprocket bolts.
  20.  
  21. Pull the camshaft sprocket and timing chain off. The sprocket is a tight fit, so you'll have to tap it loose with a plastic mallet.
  22.  
  23. Install two 5 / 16 in.-18 bolts in the holes in the front of the camshaft and carefully pull the camshaft from the block.
  24.  

To install:
  1. Liberally coat camshaft and bearing with heavy engine oil or engine assembly lubricant and insert the cam into the engine.
  2.  
  3. Install the distributor using the locating marks made during removal. (If any problems are encountered, refer to distributor removal and installation)
  4.  
  5. Install the camshaft sprocket bolts and tighten them to 20 ft. lbs. (27 Nm) on 1987-95 models or 10 ft. lbs. (14 Nm) on 1996-97 models.
  6.  
  7. Install the lifters, pushrods, and rocker arms.
  8.  
  9. Install the intake manifold.
  10.  
  11. Install the front cover.
  12.  
  13. Install the torsional damper and pulley.
  14.  
  15. Install the water pump.
  16.  
  17. Connect the hoses at the water pump.
  18.  
  19. Install the cylinder head covers.
  20.  
  21. Install the alternator and drive belt(s).
  22.  
  23. Install the fan shroud and radiator.
  24.  
  25. Fill the cooling system.
  26.  
  27. Install the air conditioning compressor.
  28.  
  29. Install the grille.
  30.  
  31. Install the air cleaner.
  32.  
  33. Connect the battery.
  34.  

Diesel Engines

See Figures 7, 8 and 9

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the cooling system.
  4.  
  5. Remove the air inlet duct and hood latch.
  6.  
  7. If equipped, remove the cruise control motor and windshield washer reservoir.
  8.  
  9. Remove the fan shroud.
  10.  
  11. Remove the radiator and fan.
  12.  
  13. Remove the headlight bezels, grille, bumper and lower valance panel.
  14.  
  15. Remove the coolant recovery reservoir.
  16.  
  17. If necessary, remove the upper tie bar.
  18.  


CAUTION
Please refer to General Information & Maintenance before discharging the compressor or disconnecting air conditioning lines. Damage to the air conditioning system or personal injury could result. Consult your local laws concerning refrigerant discharge and recycling. In many areas it may be illegal for anyone but a certified technician to service the A/C system. Always use an approved recovery station when discharging the air conditioning.

  1. Remove the condenser.
  2.  
  3. If applicable, remove the vacuum pump and the oil pump drive.
  4.  
  5. If necessary, remove the power steering pump and the generator and lay them aside.
  6.  
  7. If the van is equipped with air conditioning, remove the compressor (with the lines attached) and position it out of the way.
  8.  
  9. Remove the cylinder head covers.
  10.  
  11. On early model vehicles, remove the rocker shaft assemblies and pushrods. Place the pushrods in order in a rack (easily by punching holes in a piece of heavy cardboard and numbering the holes) so that they can be installed in correct order.
  12.  
  13. On late model engines, remove the cylinder heads as previously detailed.
  14.  
  15. Remove the front cover.
  16.  
  17. Remove the timing chain assembly.
  18.  
  19. Remove the fuel pump. Remove the front engine mount through-bolts.
  20.  
  21. Remove the camshaft retainer plate.
  22.  
  23. Remove the camshaft by carefully sliding it out of the block.
  24.  

Whenever a new camshaft installed, GM recommends replacing all the valve lifters, as well as the oil filter. The engine oil must be changed. These measures will help ensure proper wear characteristics of the new camshaft.

To install:
  1. Coat the camshaft lobes with Molykote® or an equivalent lube. Liberally tube the camshaft journals with clean engine oil and install the camshaft carefully.
  2.  
  3. Install the camshaft retainer plate and tighten the bolts to 17 ft. lbs. (23 Nm).
  4.  
  5. Install the front engine mount bolts and tighten them to 70 ft. lbs. (95 Nm). Tighten the nut to 50 ft. lbs. (70 Nm).
  6.  
  7. Install the fuel pump.
  8.  
  9. Install the timing chain assembly.
  10.  
  11. Install the front cover.
  12.  
  13. Install the valve lifters, guide plates and clamps, and rotate the crankshaft so that the lifters are free to travel.
  14.  
  15. Install the cylinder heads.
  16.  
  17. Install the pushrods in their original order. Install the rocker shaft assemblies, then install the cylinder head covers.
  18.  
  19. Install the oil pump drive.
  20.  
  21. Install the compressor.
  22.  
  23. Install the power steering pump.
  24.  
  25. Install the alternator.
  26.  
  27. Install the water pump.
  28.  
  29. Install the vacuum pump.
  30.  
  31. Install the radiator and fan.
  32.  
  33. Install the air conditioning condenser. Have the A/C system charged by a qualified, certified technician. Refer to General Information & Maintenance for additional information.
  34.  
  35. Install the fan shroud.
  36.  
  37. Install the grille, valance and headlight bezel assemblies.
  38.  
  39. Fill the cooling system and connect the battery.
  40.  
  41. Install the engine cover.
  42.  

INSPECTION



Run-Out

See Figure 7

Camshaft runout should be checked when the camshaft has been removed from the engine. An accurate dial indicator is needed for this procedure; engine specialists and most machine shops have this equipment. If you have access to a dial indicator, or can take your camshaft to someone who does, measure the camshaft bearing journal run-out. If the run-out exceeds the limit replace the camshaft.



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Fig. Fig. 7: Checking camshaft run-out

Lobe Height

See Figures 8 and 9

Use a micrometer to check camshaft (lobe) height, making sure the anvil and the spindle of the micrometer are positioned directly on the heel and tip of the camshaft lobe as shown in the accompanying illustration.



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Fig. Fig. 8: Checking camshaft lobe height



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Fig. Fig. 9: Checking camshaft journal diameter

End-Play

See Figure 10

After the camshaft has been installed, end-play should be checked. The camshaft sprocket should then be installed. Use a dial gauge to check the end-play, by moving the camshaft forward and backward. End-play specifications should be as noted in the Camshaft Specifications chart.



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Fig. Fig. 10: Checking camshaft end-play

 
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