GM Blazer/Jimmy/Typhoon/Bravada 1983-1993 Repair Guide

Rocker Arms and Push Rods

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REMOVAL & INSTALLATION



1.9L Engine

See Figure 1

  1. Remove the rocker arm cover from the cylinder head.
  2.  
  3. Starting with the outer rocker arm shaft bracket, loosen the bracket nuts a little at a time (in sequence), then remove the nuts.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Rocker arm shaft removal/installation - 1.9L engine

  1. To disassemble the rocker arm shaft assembly, remove the spring from the rocker arm shaft, then the rocker arm brackets and arms.
  2.  

Valve train components which are to be reused MUST be installed in their original positions. If removed, be sure to tag or arrange all rocker arms and pushrods to assure proper installation.

To install:
  1. Inspect the rocker arm shafts for runout. Run-out should not exceed 0.0079 in. (0.20mm)
  2.  
  3. Measure the rocker arm to shaft clearance. Clearance should not exceed 0.0078 in. (0.20mm)
  4.  
  5. Check the face of the rocker arms for wear and/or damage, replace the rocker arms and/or shafts if not within specification.
  6.  
  7. Using clean engine oil or a suitable engine pre-lube, lubricate all of the moving parts. Pre-lube is better if the engine will sit for some time before it is started, while engine oil should be sufficient if the engine is to used immediately after repairs are completed.
  8.  
  9. Assemble the rocker arm shaft brackets and rocker arms to the shaft so that the cylinder number (on the upper face of the bracket) is pointed to the front of the engine.
  10.  
  11. Align the mark on the No. 1 rocker arm shaft bracket with the mark on the intake and exhaust valve side rocker arm shaft.
  12.  
  13. Check the amount of projection of the rocker arm shaft. The intake side should be longer when the holes in the shaft are aligned with the holes in the bracket.
  14.  
  15. Place the springs in position between the shaft bracket and rocker arm.
  16.  
  17. Check that the punch mark is turned upward, then install the shaft bracket assembly onto the head studs. Align the mark on the camshaft with the mark on the No. 1 rocker arm shaft bracket.
  18.  
  19. Tighten the bracket studs to 16 ft. lbs. (22 Nm) and adjust the valves.
  20.  

The valves are adjusted with the engine Cold.

  1. Using a wrench on the damper pulley bolt or using a remote starter button, turn the crankshaft until the No. 1 piston is at TDC of the compression stroke. You will know when the No. 1 piston is on it's compression stroke because both the intake and exhaust valves will remain closed as the crankshaft damper mark approaches the timing scale. If the rocker arms move, the engine is in the No. 4 firing position. Turn the engine over one revolution. Remove the distributor cap and ensure that the rotor is pointing to the No. 1 position on the cap.
  2.  

Another method to tell when the piston is coming up on the compression stroke is by removing the spark plug and placing your thumb over the hole, you will feel the air being forced out of the spark plug hole. Stop turning the crankshaft when the TDC timing mark on the crankshaft pulley is directly aligned with the timing mark pointer or the zero mark on the scale.

  1. With the No. 1 piston at TDC of the compression stroke, use a 0.006 in. (0.152mm) feeler gauge, to set intake valves of cylinders No. 1 & 2. Using a 0.010 in. (0.254mm) feeler gauge, set the exhaust valves of cylinders No. 1 & 3.
  2.  

When adjusting the valve clearance, loosen the locknut with an open-end wrench, then turn the adjuster screw with a screwdriver and retighten the locknut. The proper thickness feeler gauge should pass between the camshaft and the rocker with a slight drag when the clearance is correct.

  1. Rotate the engine one complete revolution, so that cylinder No. 4 is on the TDC of its compression stroke and the timing marks are aligned. This time the No. 4 cylinder valves remain closed as the timing mark approaches the scale.
  2.  
  3. With cylinder No. 4 on the TDC of the compression stroke, use a 0.006 in. (0.152mm) feeler gauge, to set intake valves of cylinders No. 3 & 4. Using a 0.010 in. (0.254mm) feeler gauge, set the exhaust valves of cylinders No. 2 & 4.
  4.  
  5. When the valves are properly adjusted, install the rocker arm cover.
  6.  
  7. Start and run the engine, then check ignition and carburetor adjustments.
  8.  

2.0L Engine

See Figure 2

  1. Remove the rocker arm cover from the cylinder head.
  2.  
  3. Remove the rocker arm nuts, the ball washers and the rocker arms off the studs, then lift out the pushrods.
  4.  

Valve train components which are to be reused MUST be installed in their original positions. If removed, be sure to tag or arrange all rocker arms and pushrods to assure proper installation.

To install:
  1. Coat the bearing surfaces of the rocker arms and the rocker arm ball washers with Molykote® or equivalent pre-lube.
  2.  



Click image to see an enlarged view

Fig. Fig. 2: Rocker arm removal/installation - 2.0L engine

  1. Install the pushrods making sure that they seat properly in the lifter.
  2.  
  3. Install the rocker arms, ball washers and the nuts, then tighten the rocker arm nuts until there is little or no valve lash.
  4.  

Each valve must be adjusted when the lifter is sitting on the base circle of the camshaft, not the raised section of the lobe.

  1. Rotate the crankshaft until the mark on the crankshaft pulley aligns with the 0 mark on the timing plate. Make sure that the No. 1 cylinder is positioned on the compression stroke. You will know when the No. 1 piston is on it's compression stroke because both the intake and exhaust valves will remain closed as the crankshaft damper mark approaches the timing scale. If the No. 1 valves move as the timing mark approaches TDC, the engine is in the No. 4 firing position; rotate the engine one complete revolution and it will be in the No. 1 position.
  2.  

Another method to tell when the piston is coming up on the compression stroke is by removing the spark plug and placing your thumb over the hole, you will feel the air being forced out of the spark plug hole. Stop turning the crankshaft when the TDC timing mark on the crankshaft pulley is directly aligned with the timing mark pointer or the zero mark on the scale.

  1. When the engine is on the No. 1 firing position, adjust the following valves:
  2.  
  3. Exhaust - 1, 3
  4.  
  5. Intake - 1, 2
  6.  
  7. To adjust the valves, back-out the adjusting nut until lash can be felt at the pushrod, then turn the nut until all of the lash is removed.
  8.  

To determine is all of the lash is removed, turn the pushrod with your fingers until the movement is removed.

  1. When all of the lash has been removed, turn the adjusting nut an additional 1 1 / 2 turns; this will center the lifter plunger.
  2.  
  3. Crank the engine one complete revolution until the timing tab (0° mark) and the crankshaft pulley mark are again in alignment. Now the engine is in the No. 4 firing position. Adjust the following valves:
  4.  
  5. Exhaust - 2, 4
  6.  
  7. Intake - 3, 4
  8.  
  9. Install the rocker arm cover.
  10.  
  11. Start and run the engine, then check and adjust the timing and the idle speed, as necessary.
  12.  

2.2L Diesel Engine

See Figure 3

  1. Remove the rocker cover from the cylinder head.
  2.  
  3. Remove the rocker arm bracket-to-cylinder head bolts in sequence, commencing with the outer ones.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: Rocker arm shaft removal/installation - 2.2L diesel engine

  1. Remove the rocker arm, the bracket and shaft assembly.
  2.  
  3. Remove the snapring, the rocker arms, the springs and the brackets.
  4.  

Valve train components which are to be reused MUST be installed in their original positions. If removed, be sure to tag or arrange all rocker arms and pushrods to assure proper installation.

To install:
  1. Inspect the rocker arm shafts for runout. Run-out should not exceed 0.0079 in. (0.20mm)
  2.  
  3. Measure the rocker arm to shaft clearance. Clearance should not exceed 0.0078 in. (0.20mm)
  4.  
  5. Check the face of the rocker arms for wear and/or damage, replace the rocker arms and/or shafts if not within specification.
  6.  
  7. Using clean engine oil or a suitable engine pre-lube, lubricate all of the moving parts. Pre-lube is better if the engine will sit for some time before it is started, while engine oil should be sufficient if the engine is to used immediately after repairs are completed.
  8.  
  9. Position the brackets with the "F" marks facing the front of the engine. Working from the center outward, torque the bracket-to-cylinder head bolts to 16 ft. lbs. (22 Nm).
  10.  

The valves are adjusted with the engine Cold.

  1. Using a wrench on the damper pulley bolt or using a remote starter button, turn the crankshaft until the No. 1 piston is at TDC of the compression stroke. You will know when the No. 1 piston is on it's compression stroke because both the intake and exhaust valves will remain closed as the crankshaft damper mark approaches the timing scale. If the rocker arms move, the engine is in the No. 4 firing position. Turn the engine over one revolution.
  2.  

Another method to tell when the piston is coming up on the compression stroke is by removing the glow plug and placing your thumb over the hole, you will feel the air being forced out of the plug hole. Stop turning the crankshaft when the TDC timing mark on the crankshaft pulley is directly aligned with the timing mark pointer or the zero mark on the scale.

  1. With the No. 1 piston at TDC of the compression stroke, use a 0.016 in. (0.40mm) feeler gauge, to set the intake valves of cylinders No. 1, 2 & 3, then set the exhaust valve of cylinder No. 1.
  2.  

When adjusting the valve clearance, loosen the locknut with an open-end wrench, then turn the adjuster screw with a screwdriver and retighten the locknut. The proper thickness feeler gauge should pass between the camshaft and the rocker with a slight drag when the clearance is correct.

  1. Rotate the engine one complete revolution, so that cylinder No. 4 is on the TDC of its compression stroke and the timing marks are aligned. This time the No. 4 cylinder valves remain closed as the timing mark approaches the scale.
  2.  
  3. With cylinder No. 4 on the TDC of the compression stroke, use a 0.016 in. (0.40mm) feeler gauge, to set the intake valve of cylinder No. 4, then the exhaust valves of cylinders No. 2, 3 & 4.
  4.  
  5. With the valves properly adjusted, install the rocker arm cover.
  6.  

2.5L Engine

See Figure 4

  1. Remove the rocker arm cover from the cylinder head.
  2.  
  3. Using a socket wrench, remove the rocker arm bolts, the ball washer and the rocker arm.
  4.  



Click image to see an enlarged view

Fig. Fig. 4: Rocker arm removal/installation - 2.5L engine

If only the pushrod is to be removed, back off the rocker arm bolt, swing the rocker arm aside and remove the pushrod. When removing more than one assembly, at the same time, be sure to keep them in order for reassembly purposes.

  1. If necessary, remove the pushrods and guides.
  2.  
  3. Inspect the rocker arms and ball washers for scoring and/or other damage, replace them (if necessary).
  4.  

If replacing worn components with new ones, be sure to coat the new parts with Molykote® or an equivalent pre-lube before installation.

To install:
  1. If removed, install the pushrods and guides.
  2.  
  3. Install the rocker arms, ball washers and retaining bolts. Tighten the rocker arm-to-cylinder head bolt for each valve to 22 ft. lbs. (30 Nm), but only tighten the bolt with the hydraulic lifter for that valve on the base circle of the camshaft. DO NOT tighten the bolts while the lifter is resting on the raised portion of the lobe and DO NOT overtighten the bolts.
  4.  

Valve lash is NOT adjustable on the 2.5L engine.

  1. Install the rocker arm cover to the cylinder head.
  2.  

2.8L Engine

See Figures 5, 6, 7, 8 and 9

  1. Remove the rocker arm cover(s) from the cylinder head.
  2.  

If only the pushrod is to be removed, loosen the rocker arm nut, swing the rocker arm to the side and remove the pushrod.

  1. Remove the rocker arm nut, the rocker arm and the ball washer.
  2.  
  3. Withdraw the pushrod from the cylinder head.
  4.  

To install:
  1. Inspect and replace components if worn or damaged.
  2.  
  3. Coat the bearing surfaces of the rocker arms and the rocker arm ball washers with Molykote® or equivalent pre-lube.
  4.  
  5. Install the pushrods making sure that they seat properly in the lifter.
  6.  
  7. Install the rocker arms, ball washers and the nuts, then tighten the rocker arm nuts until there is little or no valve lash.
  8.  

Each valve must be adjusted when the lifter is sitting on the base circle of the camshaft, not the raised section of the lobe.

  1. Rotate the crankshaft until the mark on the crankshaft pulley aligns with the 0 mark on the timing plate. Make sure that the No. 1 cylinder is positioned on the compression stroke. You will know when the No. 1 piston is on it's compression stroke because both the intake and exhaust valves will remain closed as the crankshaft damper mark approaches the timing scale. If the No. 1 valves move as the timing mark approaches TDC, the engine is in the No. 4 firing position; rotate the engine one complete revolution and it will be in the No. 1 position.
  2.  

Another method to tell when the piston is coming up on the compression stroke is by removing the spark plug and placing your thumb over the hole, you will feel the air being forced out of the spark plug hole. Stop turning the crankshaft when the TDC timing mark on the crankshaft pulley is directly aligned with the timing mark pointer or the zero mark on the scale.

  1. When the engine is on the No. 1 firing position, adjust the following valves:
  2.  
  3. Intake - 1, 5 & 6
  4.  
  5. Exhaust - 1, 2 & 3
  6.  
  7. To adjust the valves, back-out the adjusting nut until lash can be felt at the pushrod, then turn the nut until all of the lash is removed.
  8.  

To determine is all of the lash is removed, turn the pushrod with your fingers until the movement is removed.

  1. When all of the lash has been removed, turn the adjusting an additional 1 1 / 2 turns; this will center the lifter plunger.
  2.  
  3. Crank the engine one complete revolution until the timing tab (0° mark) and the crankshaft pulley mark are again in alignment. Now the engine is in the No. 4 firing position. Adjust the following valves:
  4.  
  5. Intake - 2, 3 & 4
  6.  
  7. Exhaust - 4, 5 & 6
  8.  
  9. Install the rocker arm cover(s).
  10.  
  11. Start and run the engine, then check and adjust the timing and the idle speed, as applicable.
  12.  



Click image to see an enlarged view

Fig. Fig. 5: For access to the rocker arms, remove the valve cover from the cylinder head



Click image to see an enlarged view

Fig. Fig. 6: Loosen the rocker arm retaining nut



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Fig. Fig. 7: Remove the retaining nut and ball washer from the top of the rocker arm



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Fig. Fig. 8: With the nut and washer removed, the rocker arm is free to be pulled from the stud



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Fig. Fig. 9: The pushrod may now be pulled from the cylinder head

4.3L Engine
  1. Remove the rocker arm cover(s) from the cylinder head.
  2.  

If only the pushrod is to be removed, loosen the rocker arm nut, swing the rocker arm to the side and remove the pushrod.

  1. Remove the rocker arm nut, the rocker arm and the ball washer.
  2.  
  3. Withdraw the pushrod from the cylinder head.
  4.  

To install:
  1. Inspect and replace components if worn or damaged.
  2.  
  3. Coat the bearing surfaces of the rocker arms and the rocker arm ball washers with Molykote® or equivalent pre-lube.
  4.  
  5. Install the pushrods making sure that they seat properly in the lifter.
  6.  
  7. Install the rocker arms, ball washers and the nuts.
  8.  
  9. For the 4.3L (VIN W) engine and any 1993 4.3L (VIN Z) engines which are equipped with screw-in type rocker arm studs with positive stop shoulders, tighten the rocker arm adjusting nuts against the stop shoulders to 20 ft. lbs. (27 Nm). No further adjustment is necessary, or possible.
  10.  
  11. For all 1988-92 and most later 4.3L (VIN Z) engines (which are not equipped with screw-in type rocker arm studs and positive stop shoulders), properly adjust the valve lash. For details on valve lash adjustment, please refer to General Information & Maintenance of this guide.
  12.  
  13. Install the rocker arm cover(s) to the cylinder head.
  14.  
  15. Start and run the engine, then check for leaks and for proper ignition timing adjustment.
  16.  

 
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