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Mazda Trucks 1972-1986 Repair Guide

Rocker Shafts

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REMOVAL & INSTALLATION



1,586cc, 1,796cc and 1,970cc Engines

See Figures 1, 2 and 3

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Fig. Fig. 1: Rocker arm assembly used on the 1,586cc, 1,796cc and 1,970cc engines



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Fig. Fig. 2: Proper positioning of the rocker arm adjusting screw ballmake sure the flat portion of the ball contacts the valve tip



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Fig. Fig. 3: Exhaust rockers may have a slight offset depending on engine model

This operation should only be performed on a cold engine; the bolts which hold the rocker shafts in place also hold the cylinder head to the block.

  1. Raise the hood and cover the fenders.
  2.  
  3. Disconnect the choke cable, if so equipped.
  4.  
  5. If equipped, disconnect the air by-pass valve cable.
  6.  
  7. Disconnect the spark plug wires. Remove the wires from the spark plug wire clips on the rocker covers and position them out of the way.
  8.  
  9. Remove the rocker cover and discard the gasket.
  10.  
  11. Remove the rocker arm shaft attaching bolts evenly and remove the rocker arm shafts.
  12.  

To install:
  1. Install the rocker arm assemblies on the cylinder head. Install the balls on each rocker arm as shown. Temporarily tighten the cylinder head bolts to specifications and offset each rocker arm support 1mm (0.04 in.) from the valve stem center. Torque the bolts to specifications.
  2.  
  3. Adjust the valves cold.
  4.  
  5. Clean the mating surfaces of the cylinder head and rocker cover.
  6.  
  7. Install the rocker cover with a new gasket. Torque the bolts to 24-36 in. lbs.
  8.  
  9. Install the spark plug wire on the plugs. Place the wires in the clips on the rocker cover. Connect the choke and air by-pass valve cable.
  10.  
  11. Start the engine and check for leaks.
  12.  
  13. Allow the engine to reach operating temperature, torque the head bolts to specifications and adjust the valves hot.
  14.  

1,998cc Engine See Figures 4 and 5

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Fig. Fig. 4: Rocker arm torque sequence for the 1,998cc engine



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Fig. Fig. 5: Removing the rocker arm and shaft assemblysome engines use the cylinder head bolts to retain the assembly, while others have separate rocker arm bolts

  1. Raise the hood and cover the fenders.
  2.  
  3. Disconnect the accelerator cable, if necessary.
  4.  
  5. If equipped, disconnect the air by-pass valve cable.
  6.  
  7. Disconnect the spark plug wires. Remove the wires from the spark plug wire clips on the rocker covers and position them out of the way.
  8.  
  9. Remove the rocker cover and discard the gasket.
  10.  
  11. Remove the rocker arm shaft attaching bolts evenly, in the order shown, and remove the rocker arm shafts.
  12.  

To install:
  1. Install the rocker arm assemblies on the cylinder head. Torque the bolts, in the order shown, to 13-20 ft. lbs.
  2.  
  3. Check the valve adjustment and reset, if necessary.
  4.  
  5. Clean the mating surfaces of the cylinder head and rocker cover.
  6.  
  7. Install the rocker cover with a new gasket. Torque the bolts to 24-36 in. lbs.
  8.  
  9. Install the spark plug wire on the plugs. Place the wires in the clips on the rocker cover. Connect the choke and air by-pass valve cable.
  10.  
  11. Start the engine and check for leaks.
  12.  
  13. Allow the engine to reach operating temperature, torque the head bolts to specifications and adjust the valves hot.
  14.  

2,209cc Diesel Engine See Figure 6

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Fig. Fig. 6: Exploded view of the diesel rocker arm components

This operation should only be performed on a cold engine; the bolts which hold the rocker shafts in place also hold the cylinder head to the block.

  1. Raise the hood and cover the fenders.
  2.  
  3. Disconnect the accelerator cable, if necessary.
  4.  
  5. Remove the rocker cover and discard the gasket.
  6.  
  7. Remove the rocker arm shaft attaching bolts evenly and remove the rocker arm shafts.
  8.  
  9. Lift out the pushrods, keeping them in order for proper installation. When installing the pushrods, make sure they are seated in the depressed bottom section of the tappets.
  10.  

To install:
  1. Install the rocker arm assemblies on the cylinder head. Torque the bolts to specifications.
  2.  
  3. Adjust the valves cold.
  4.  
  5. Clean the mating surfaces of the cylinder head and rocker cover.
  6.  
  7. Install the rocker cover with a new gasket. Torque the bolts to 24-36 in. lbs.
  8.  
  9. Install the spark plug wire on the plugs. Place the wires in the clips on the rocker cover. Connect the choke and air by-pass valve cable.
  10.  
  11. Start the engine and check for leaks.
  12.  
  13. Allow the engine to reach operating temperature, torque the head bolts to specifications and adjust the valves hot.
  14.  

DISASSEMBLY Except Diesel Engine



Don't mix up the parts! Keep them identified!

  1. Lay out a clean piece of heavy paper marked with a location for each component.
  2.  
  3. Remove the end caps and slide each piece from the shafts, placing it on its identifying mark on the paper.
  4.  

Don't hammer off any piece. If any piece is difficult to remove, soak it in Liquid Wrench, WD-40 or similar solution. Hammering on any part will distort it!

  1. Check each component for wear, damage, heat scoring or cracks. Replace any suspect part. Clean all parts in a safe solvent. Make sure that all oil holes are clear.
  2.  
  3. Assembly is the reverse of disassembly.
  4.  

Diesel Engine

Don't mix up the parts! Keep them identified!

  1. Lay out a clean piece of heavy paper marked with a location for each component.
  2.  
  3. Remove the snaprings and washers from the ends of the shaft. Slide each piece from the shaft, placing it on its identifying mark on the paper.
  4.  

Don't hammer off any piece. If any piece is difficult to remove, soak it in Liquid Wrench, WD-40 or similar solution. Hammering on any part will distort it!

  1. Check each component for wear, damage, heat scoring or cracks. Replace any suspect part. Clean all parts in a safe solvent. Make sure that all oil holes are clear.
  2.  
  3. Assembly is the reverse of disassembly.
  4.  

 
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