GM Metro/Sprint 1985-1993 Repair Guide

Camshaft and Bearings

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REMOVAL and INSTALLATION

Sprint

See Figures 1, 2 and 3



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Fig. Fig. 1: Pulley pin, slot and pulley bolt



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Fig. Fig. 2: Fuel pump rod



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Fig. Fig. 3: Rocker arms, springs, shafts and screws - Metro

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Remove the cylinder head cover assembly.
  6.  
  7. Set the engine up on top dead center of the compression stroke on the No. 1 cylinder. Make an alignment mark on the distributor cap and engine block and remove the distributor assembly.
  8.  
  9. Remove the crankshaft pulley, timing belt outside cover and the timing belt.
  10.  

After removing the timing belt, set the key on the crankshaft in position by turning the crankshaft. This is to prevent interference between the valves and the piston when reinstalling the camshaft.

  1. Remove the camshaft timing belt gear. Lock the camshaft with a proper size rod inserted into the hole 0.39 in. (10mm) in it. Loosen the camshaft timing belt gear bolt.
  2.  

The mating surface of the cylinder head and cover must not be damaged in this work. So, put a clean shop cloth between the rod and mating surfaces and use care not to bump the rod against the mating surfaces hard when loosening.

  1. Remove the fuel pump and fuel pump rod. Remove the camshaft from the cylinder head.
  2.  

To install:
  1. Apply engine oil to lobes and journals on camshaft and oil seal on cylinder head.
  2.  
  3. Install the camshaft into the cylinder head.
  4.  
  5. Install the timing belt inside cover and camshaft pulley. Fit pulley pin on camshaft into slot on camshaft pulley. Tighten the pulley bolt to 41-46 ft. lbs.. (55-64 Nm).
  6.  
  7. Install the fuel pump rod, gasket and fuel pump to the cylinder head.
  8.  
  9. Apply engine oil to rocker arms and rocker arm shafts.
  10.  

The two rocker arm shafts are different. To distinguish between the two, the dimensions of their stepped ends differ. The intake rocker arm step measures 0.55 in. (14mm). The exhaust rocker arm step measures 0.59 in. (15mm).

  1. Install the intake rocker arm shaft facing its stepped end to camshaft pulley side, and the exhaust rocker arm shaft facing its stepped end to distributor side.
  2.  
  3. Install rocker arms, springs and rocker arm shafts. Tighten the rocker arm shaft screws to 7-9 ft. lbs.. (9-12 Nm).
  4.  
  5. Install the distributor.
  6.  
  7. Install the belt tensioner, timing belt, outside cover, crankshaft pulley and water pump belt.
  8.  
  9. Adjust the intake and exhaust valves.
  10.  
  11. Install the cylinder head cover and air cleaner.
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Adjust the ignition timing.
  16.  

Metro

See Figures 4, 5, 6 and 7



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Fig. Fig. 4: Position of the crankshaft key for camshaft removal



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Fig. Fig. 5: Position of camshaft housings



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Fig. Fig. 6: Removing the valve cover to expose the camshaft - Metro



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Fig. Fig. 7: The camshaft is held in place by three bearing caps - Metro

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Remove the cylinder head cover assembly.
  6.  
  7. Set the engine up on top dead center of the compression stroke on the No. 1 cylinder. Make an alignment mark on the distributor cap and engine block and remove the distributor assembly.
  8.  
  9. Remove the crankshaft pulley, timing belt outside cover and the timing belt.
  10.  

After removing the timing belt, set the key on the crankshaft in position by turning the crankshaft. This is to prevent interference between the valves and the piston when reinstalling the camshaft.

  1. Remove the camshaft timing belt gear. Lock the camshaft with a proper size rod inserted into the hole 0.39 in. (10mm) in it. Loosen the camshaft timing belt gear bolt.
  2.  

The mating surface of the cylinder head and cover must not be damaged in this work. So, put a clean shop cloth between the rod and mating surfaces and use care not to bump the rod against the mating surfaces hard when loosening.

  1. Remove the camshaft housings from the cylinder head.
  2.  
  3. Remove the camshaft from the cylinder head.
  4.  
  5. Remove the HVL adjusters and submerge in oil until reinstallation.
  6.  

To install:
  1. Fill the oil passage in the cylinder head with engine oil. Pour engine oil through camshaft journal oil holes and check that engine oil comes out from oil holes in HVL adjuster bores. Install HVL adjusters.
  2.  
  3. Install the camshaft to the cylinder head. After applying engine oil to the camshaft journal and all around the cam, position the camshaft into the cylinder head so that the camshaft timing belt gear pin hole in camshaft is at the lower position.
  4.  
  5. Install the camshaft housing to the camshaft and the cylinder head.
  6.  
  7. Apply the engine oil to the sliding surface of each housing against the camshaft journal.
  8.  
  9. Apply the sealant to the mating surface of the No. 1 and No. 3 housing which will mate with the cylinder head.
  10.  
  11. There are marks provided on each camshaft housing indicating position and direction for installation. Install the housing as indicated by these marks.
  12.  
  13. As the camshaft housing No. 1 retains the camshaft in the proper position as to the thrust direction, make sure to first fit the No. 1 housing to the No. 1 journal of the camshaft securely.
  14.  
  15. After applying the engine oil to the housing bolts, tighten them temporarily. Then tighten in the proper sequence. Tighten the bolts a little at a time and evenly among bolts, repeat the tightening sequence 3 to 4 times before they are tighten to the proper torque of 8 ft. lbs.. (11 Nm).
  16.  
  17. Install the camshaft oil seal. After applying engine oil to the oil seal lip, press-fit the camshaft oil seal until the oil seal surface becomes flush with the housing surfaces.
  18.  
  19. Install the camshaft timing belt gear to the camshaft after installing the dwell pin to the camshaft. While locking the camshaft, install the camshaft pulley and retaining bolt and torque the bolt to 44 ft. lbs.. (60 Nm).
  20.  
  21. Install the cylinder head cover to the cylinder head.
  22.  
  23. Install the timing belt, timing belt outside cover, crankshaft pulley, coolant pump pulley and coolant pump belt.
  24.  
  25. Install the distributor assembly into the engine.
  26.  
  27. Install the air cleaner assembly and reinstall the negative battery cable.
  28.  
  29. Adjust the ignition timing.
  30.  

INSPECTION



See Figures 8, 9, 10, 11 and 12



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Fig. Fig. 8: Measuring rocker arm shaft runout



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Fig. Fig. 9: Measuring rocker arm shaft and rocker arm bore to determine clearance



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Fig. Fig. 10: Measuring camshaft lobe height



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Fig. Fig. 11: Measuring camshaft runout



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Fig. Fig. 12: Measuring camshaft journal diameter and cylinder head camshaft bore to determine clearance

  1. On Sprint models, inspect the adjusting screw and rocker arm. If the tip of the adjusting screw is badly worn, replace the screw. The arm must be replaced if its cam riding face is badly worn.
  2.  
  3. On Sprint models, inspect the rocker arm shaft runout. Using V-blocks and a dial gauge, check runout. If runout exceeds the limit, replace the rocker arm shaft.
  4.  
  5. On Sprint models, inspect rocker arm-to-rocker arm shaft clearance. Using a micrometer and bore gauge, measure the rocker shaft diameter and rocker arm inside diameter. The difference between the reading is the clearance. If clearance exceeds the limit, replace the shaft and/or rocker arm.
  6.  
  7. Inspect camshaft wear. Using a micrometer, measure the height of the lobe. If the height measurement is less than the limit, replace the camshaft.
  8.  
  9. Inspect the camshaft runout. Hold the camshaft between two V-blocks and measure the runout by using a dial gauge. If the runout exceeds the limit, replace the camshaft.
  10.  
  11. Inspect camshaft journal wear. Measure the journal diameter in two directions at four places to obtain four readings on each journal and measure the journal bores in the cylinder head with a bore gauge. Subtract the journal diameter measurement from the journal bore measurement to determine the journal clearance. If journal clearance exceeds the limit, replace the camshaft, and as necessary, the cylinder head.
  12.  

 
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