GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Camshaft and Bearings

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REMOVAL & INSTALLATION



See Figures 1, 2 and 3

Gasoline Engines
  1. Disconnect the negative battery cable. Drain and remove the radiator.
  2.  
  3. Have a trained technician discharge the A/C system with a recovery/recycling station. Remove the air conditioning condenser. If disconnected, immediately cap condenser openings. Remove the A/C condenser.
  4.  
  5. Remove any accessories which may interfere with camshaft removal.
  6.  
  7. Remove the intake manifold.
  8.  
  9. Remove valve covers.
  10.  
  11. Remove rocker arm and shaft assemblies, pushrods and valve lifters. Mark parts as necessary and keep pushrods in order for later assembly.
  12.  
  13. Remove timing chain cover, timing chain and sprocket. Refer to the appropriate procedure in this section.
  14.  
  15. Install long bolts into the camshaft sprocket bolt holes to help support the camshaft. Carefully slide camshaft forward, out of the bearing bores, working slowly to avoid marring the bearing surfaces. Remove camshaft.
  16.  

To install:
  1. Liberally coat the entire cam with assembly lube or equivalent. Slowly slide the camshaft into the engine block, exercising extreme care not to damage the cam bearings.
  2.  
  3. Install the timing chain and sprockets and timing chain cover. Refer to the appropriate procedure in this section.
  4.  
  5. Install the rocker arm and shaft assemblies, pushrods and valve lifters into their original locations as removed.
  6.  
  7. Install valve covers.
  8.  
  9. Install the intake manifold.
  10.  
  11. Install any accessories which were removed.
  12.  
  13. Install the air conditioning condenser. Evacuate and recharge the A/C system as outlined in Routine Maintenance .
  14.  
  15. Install and refill the radiator. Reconnect the negative battery cable.
  16.  
  17. Start the engine and check for proper operation and leaks.
  18.  



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Fig. Fig. 1: Removing the crankshaft sprocket



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Fig. Fig. 2: Removing the camshaft from the engine

Diesel Engine

If equipped with air conditioning, the system must be discharged before the camshaft can be removed. The condenser must also be removed from the vehicle.

Removal of the camshaft also requires removal of the injection pump drive and driven gears, removal of the intake manifold, disassembly of the valve lifters, and re-timing of the injection pump.

  1. Disconnect the negative battery cables. Drain the coolant. Remove the radiator.
  2.  


CAUTION
When draining the coolant, keep in mind that cats and dogs are attracted by the ethylene glycol antifreeze, and are quite likely to drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantity. Always drain the coolant into a sealable container. Coolant should be reused unless it is contaminated or several years old.

  1. Remove the intake manifold and gasket and the front and rear intake manifold seals. Refer to the Intake Manifold removal and installation procedure in this section.
  2.  
  3. Remove the balancer pulley and the balancer. See Caution under diesel engine front cover removal and installation, above. Remove the engine front cover using the appropriate procedure.
  4.  
  5. Remove the valve covers. Remove the rocker arms, pushrods and valve lifters. Be sure to keep the parts in order so that they may be returned to their original positions.
  6.  
  7. Remove the camshaft sprocket retaining bolt, and remove the timing chain and sprockets, using the procedure outlined earlier.
  8.  
  9. Position the camshaft dowel pin at the 3 o'clock position on the V8.
  10.  
  11. On V8s, push the camshaft rearward and hold it there, being careful not to dislodge the oil gallery plug at the rear of the engine. Remove the fuel injection pump drive gear by sliding it from the camshaft while rocking the pump driven gear.
  12.  
  13. To remove the fuel injection pump driven gear, remove the pump adapter, the snapring, and remove the selective washer. Remove the driven gear and spring.
  14.  

Thread long bolts into the camshaft-to-sprocket bolt holes. The bolts are used to support the camshaft during removal.

  1. Remove the camshaft by sliding it out the front of the engine. Be extremely careful not to allow the cam lobes to contact any of the bearings, or the journals to dislodge the bearings during camshaft removal. Do not force the camshaft, or bearing damage will result.
  2.  

To install:
  1. If either the injection pump drive or driven gears are to be replaced, replace both gears.
  2.  
  3. Coat the camshaft and the cam bearings with a high quality assembly lube, GM lubricant #1052365 or the equivalent.
  4.  
  5. Carefully slide the camshaft into position in the engine.
  6.  
  7. Fit the crankshaft and camshaft sprockets, aligning the timing marks as shown in the timing chain removal and installation procedure, above. Remove the sprockets without disturbing the timing.
  8.  
  9. Install the injection pump driven gear, spring, shim, and snapring. Check the gear end play. If the end play is not within 0.002-0.006 in. (0.0508-0.1524mm) on V8s through 1979, and 0.002-0.015 in. (0.0508-0.3810mm) on 1980 and later, replace the shim to obtain the specified clearance. Shims are available in 0.003 in. (0.0762mm) increments, from 0.080-0.115 in. (0.2032-2.9210mm).
  10.  
  11. Position the camshaft dowel pin at the 3 o'clock position. Align the zero marks on the pump drive gear and pump driven gear. Hold the camshaft in the rearward position and slide the pump drive gear onto the camshaft. Install the camshaft bearing retainer.
  12.  
  13. Install the timing chain and sprockets, making sure the timing marks are aligned.
  14.  
  15. Install the lifters, pushrods and rocker arms. See the procedure for cylinder head removal for diesel engines for lifter disassembly and draining procedures. If the lifters are not disassembled and drained, valves could be bent or pushrods damaged at start-up.
  16.  
  17. Install the injection pump adapter and injection pump. See the appropriate sections under Fuel System above for procedures.
  18.  
  19. Install the valve covers after the rocker arms have been adjusted. Be sure to install all valve parts into their original positions.
  20.  
  21. Install the front cover, balancer and pulley. Torque the balancer bolt to 200-310 ft. lbs. (270-420 Nm). See Caution under diesel engine front cover removal and installation, above.
  22.  
  23. Install the intake manifold and gaskets. Refer to the Intake Manifold removal and installation procedure in this section.
  24.  
  25. Connect the negative battery cables. Install the radiator and refill the engine coolant.
  26.  



Click image to see an enlarged view

Fig. Fig. 3: Diesel injection pump drive

INSPECTION



See Figure 4

Completely clean the camshaft with solvent, paying special attention to cleaning the oil holes. Visually inspect the cam lobes and bearing journals for excessive wear. If a lobe is questionable, have the cam checked at a reputable machine ship; if a journal or lobe is worn, the camshaft must be reground or replaced. Also have the camshaft checked for straightness on a dial indicator.

If a cam journal is worn, there is a good chance that the bearings are worn.



Click image to see an enlarged view

Fig. Fig. 4: The camshaft can be checked for wear using a dial indicator

CAMSHAFT BEARINGS



See Figures 5 and 6

If excessive camshaft wear is found, or if the engine is being completely rebuilt, the camshaft bearings should be replaced.

The front and rear bearings should be removed last, and installed first. Those bearings act as guides for the other bearings and pilot.

  1. Drive the camshaft rear plug from the block.
  2.  
  3. Assemble the removal puller with its shoulder on the bearing to be removed. Gradually tighten the puller nut until the bearing is removed.
  4.  
  5. Remove the remaining bearings, leaving the front and rear for last. To remove these, reverse the position of the puller, so as to pull the bearings toward the center of the block. Leave the tool in this position, pilot the new front and rear bearings on the installer, and pull them into position.
  6.  
  7. Return the puller to its original position and pull the remaining bearings into position.
  8.  

Ensure that the oil holes align when installing the bearings. This is very important!

  1. Replace the camshaft rear plug, and stake it into position.
  2.  
  3. Coat the bearings and camshaft with high quality assembly lube before installing the camshaft. Use long bolts threaded into the camshaft-to-sprocket bolt holes to ease installation and help prevent bearing damage.
  4.  



Click image to see an enlarged view

Fig. Fig. 5: Removing the camshaft bearings



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Fig. Fig. 6: Checking camshaft bearing hole alignment

 
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