Mazda Trucks 1972-1986 Repair Guide

Cylinder Head

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REMOVAL & INSTALLATION



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

See Figures 1 and 2

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Fig. Fig. 1: Check the cylinder block deck for warpage by running a straightedge along both sides, both ends and diagonally as shown. Use a feeler gauge along the length of the straightedge. Maximum allowable warpage is 0.003 inches within 6 inches of the deck surface



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Fig. Fig. 2: Rocker shaft/cylinder head bolt torque sequence for the 1,586cc, 1,796cc and 1,970cc engines

The engine must be cold before proceeding.

  1. Drain the cooling system.
  2.  
  3. Scribe alignment marks around the hood hinges and remove the hood.
  4.  


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

  1. Remove the air cleaner.
  2.  
  3. Disconnect the coil wire and vacuum line from the distributor.
  4.  
  5. Rotate the crankshaft to put the no. 1 cylinder at TDC on the compression stroke.
  6.  
  7. Remove the plug wires and distributor cap as a unit.
  8.  
  9. Remove the distributor.
  10.  
  11. Remove the rocker arm cover.
  12.  
  13. Raise and support the truck.
  14.  
  15. Disconnect the exhaust pipe from the manifold.
  16.  
  17. Remove the accelerator linkage.
  18.  
  19. Disconnect and tag all wiring, cable and hoses from the engine.
  20.  
  21. Remove the water pump.
  22.  
  23. Remove the nut, washer and the distributor gear from the camshaft.
  24.  
  25. Remove the nut, washer and camshaft gear. Support the timing chain from falling into the timing chain case. Do not remove the cam gear from the timing chain. The relationship between the chain and gear teeth should not be disturbed.
  26.  
  27. Remove the cylinder head bolts, and cylinder head-to-front cover bolt.
  28.  
  29. Remove the rocker arm assembly.
  30.  
  31. Remove the camshaft and camshaft gear.
  32.  
  33. Lift off the cylinder head.
  34.  
  35. Remove all tension from the timing chain.
  36.  

To install:
  1. Clean the rocker cover gasket surface at the head and the cover. Clean the head gasket surface at the head and the block. Clean the water pump gasket surface at the head and the block. Clean the water pump gasket surface at the head gasket surface and the front cover.
  2.  
  3. Check the cylinder head flatness with a straightedge and feeler blades. It should not exceed 0.08mm (0.0031 in.) in any 152mm (5.98 in.) span or 0.15mm (0.038 in.) overall. If necessary, the cylinder head can be milled, not to exceed 0.20mm (0.00787 in.).
  4.  
  5. Clean the cylinder head bolt holes of oil and dirt.
  6.  
  7. Position a new head gasket on the cylinder block.
  8.  
  9. Install the cylinder head on the block using the guides at either end of the block.
  10.  
  11. Install the camshaft on the head and camshaft gear.
  12.  
  13. Install the rocker arm assembly.
  14.  
  15. Install the head bolts. Torque the bolts to specification, in the order shown.
  16.  
  17. Install the camshaft gear washer and nut.
  18.  
  19. Install the distributor gear, washer and nut.
  20.  
  21. Time the engine. Follow the instructions under Timing Chain Tensioner Adjustment.
  22.  
  23. Adjust the timing chain tension. See Timing Chain Tensioner Adjustment.
  24.  
  25. Connect the exhaust pipe to the exhaust manifold. Lower the truck.
  26.  
  27. Install the distributor, distributor cap and plug wires.
  28.  
  29. Install the lower intake bracket bolt.
  30.  
  31. Install the accelerator linkage.
  32.  
  33. Connect the vacuum line and coil wire.
  34.  
  35. Adjust the valve clearance cold.
  36.  
  37. Install the rocker arm cover. Torque the bolts to 24-36 in. lbs. Fill the cooling system.
  38.  
  39. Run the engine until normal operating temperature is reached, and check for leaks. Adjust the valve clearance hot.
  40.  
  41. Adjust the carburetor and ignition timing. Install the air cleaner and install the hood.
  42.  

1,998cc Engine See Figures 3 through 48



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Fig. Fig. 3: After removing the air cleaner lid and filter, loosen the air injection hose clamps ...



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Fig. Fig. 4: ... and pull the hoses free from the air cleaner



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Fig. Fig. 5: Label and remove all vacuum hoses connected to the air cleaner ...



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Fig. Fig. 6: ... then loosen and remove the air cleaner-to-valve cover bolts



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Fig. Fig. 7: Loosen the fresh air hose clamp ...



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Fig. Fig. 8: ... and remove the fresh air hose



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Fig. Fig. 9: Loosen and remove the air cleaner housing-to-carburetor nuts ...



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Fig. Fig. 10: ... then lift off the air cleaner



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Fig. Fig. 11: Drain the coolant and disconnect the radiator hoses from the radiator, then loosen and remove the fan shroud attaching bolts and radiator bolts ...



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Fig. Fig. 12: ... and remove the fan shroud and radiator



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Fig. Fig. 13: Loosen the fan attaching nuts ...



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Fig. Fig. 14: ... and remove the fan



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Fig. Fig. 15: After the alternator drive belt has been removed, take off the fan pulley ...



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Fig. Fig. 16: ... and remove any additional accessory drive belts



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Fig. Fig. 17: After removing the distributor, loosen the air injection manifold nuts at the top ...



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Fig. Fig. 18: ... as well as from the bottom of the exhaust manifold, ...



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Fig. Fig. 19: ... then loosen any clamps securing the air pipes ...



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Fig. Fig. 20: ... and remove the air pipes



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Fig. Fig. 21: To gain access to the front cover, remove the fan pulley bracket, ...



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Fig. Fig. 22: ... then loosen the center crankshaft bolt and the six smaller perimeter bolts ...



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Fig. Fig. 23: ... remove the bolts ...



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Fig. Fig. 24: ... and then remove the crankshaft pulley (notice the perimeter bolt holes in the center of the pulley)install the center bolt back into the end of the crankshaft



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Fig. Fig. 25: Now remove the upper and lower timing belt cover bolts and ...



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Fig. Fig. 26: ... remove the upper cover ...



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Fig. Fig. 27: ... then the lower cover



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Fig. Fig. 28: Turn the engine in the direction of normal rotation until the letter A on the cam gear aligns with the timing mark cast into timing belt cover mounting flange (top center)



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Fig. Fig. 29: Loosen the timing belt tensioner pulley bolt (arrow), then move the pulley away from the belt and tighten the bolt again to lock the pulley in positionthere should be little or no tension left on the timing belt



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Fig. Fig. 30: Mark the timing belt and camshaft gear ...



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Fig. Fig. 31: ... then remove the belt



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Fig. Fig. 32: To remove the exhaust manifold, unscrew the oxygen sensor ...



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Fig. Fig. 33: ... then remove all the heat shield retaining bolts ...



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Fig. Fig. 34: ... and remove the heat shield ...



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Fig. Fig. 35: Remove the exhaust manifold-to-cylinder head nuts ...



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Fig. Fig. 36: ... as well as the exhaust manifold-to-catalytic converter bolts, ...



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Fig. Fig. 37: ... then pull off the exhaust manifold ...



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Fig. Fig. 38: ... and the old exhaust manifold gasket



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Fig. Fig. 39: To remove the intake manifold, label and disconnect any vacuum and electrical connections (carburetor removed for clarity) ...



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Fig. Fig. 40: ... then remove the intake manifold-to-cylinder head nuts ...



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Fig. Fig. 41: ... and pull the intake manifold away from the cylinder head. Remove the valve cover, then loosen and remove the cylinder head bolts using the proper loosening sequence ...



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Fig. Fig. 42: ... then lift off the cylinder headsome prying may be necessary, however, never hammer any object between the cylinder head and block, as this could damage the sealing surfaces



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Fig. Fig. 43: Scrape the old gasket off the block and cylinder head surfaces, and wipe them free of any grease or oil



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Fig. Fig. 44: When installing the cylinder head, use an accurate torque wrench and follow the tightening sequence and torque specifications given



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Fig. Fig. 45: View of the 1,998cc engine timing belt covers



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Fig. Fig. 46: Camshaft pin/mark alignment on the 1,998cc engine



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Fig. Fig. 47: 1,998cc engine cylinder head bolt loosening sequence



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Fig. Fig. 48: 1,998cc engine cylinder head bolt tightening (torque) sequence

The engine must be cold before proceeding.

  1. Drain the cooling system.
  2.  


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

  1. Scribe alignment marks around the hood hinges and remove the hood.
  2.  
  3. Remove the air cleaner.
  4.  
  5. Disconnect, and tag, all wires, hoses, cables, pipes and linkage from the cylinder head.
  6.  
  7. Remove the 3-way solenoid valves, but don't disconnect the vacuum tubes.
  8.  
  9. Remove the duty solenoid valves, but don't disconnect the vacuum tubes.
  10.  
  11. Remove the emissions canister.
  12.  
  13. Remove the distributor cap. Matchmark the rotor position and distributor body, and the body-to-head position. Remove the distributor. Remove the spark plugs.
  14.  
  15. Remove the intake manifold and carburetor as an assembly.
  16.  
  17. Remove the exhaust manifold.
  18.  
  19. Remove the alternator.
  20.  
  21. Disconnect the air injection pipes.
  22.  
  23. Remove the fan pulley, hub and bracket.
  24.  
  25. If so equipped, remove the air conditioning compressor drive belt.
  26.  
  27. If so equipped, remove the power steering pump drive belt.
  28.  
  29. Remove the crankshaft pulley and baffle plate.
  30.  
  31. Remove the upper, then the lower, belt covers.
  32.  
  33. Turn the crankshaft so that the A mark on the camshaft pulley is at the top, aligned with the notch in the front housing.
  34.  
  35. Loosen the tensioner lockbolt and remove the tensioner spring.
  36.  
  37. Mark the forward rotation of the belt with paint to avoid confusion upon installation. Remove the belt.
  38.  
  39. Insert a bar through the hole in the camshaft sprocket to hold it in position and remove the sprocket bolt.
  40.  
  41. Remove the rocker arm cover.
  42.  
  43. Remove the head bolts in the sequence shown, and, with the aid of an assistant or a lifting device, lift off the head.
  44.  

To install:
  1. Clean the head and block mating surfaces thoroughly and install a new head gasket on the block.
  2.  
  3. Install the head and tighten the head bolts, in the order shown, to 60-64 ft. lbs. If new head bolts are being used, make sure you use the new, surface treated plain washers.
  4.  
  5. Install the camshaft pulley with the dowel pin on the camshaft engaging the pulley slot just below the A mark on the pulley. Tighten the bolt to 40-48 ft. lbs. The timing mark on the front housing and the A mark must be aligned.
  6.  
  7. Lubricate the distributor O-ring with clean engine oil, align all the matchmarks and install the distributor.
  8.  
  9. Replace the belt if it has been contaminated by oil or grease, or shows any sign of damage, wear, cracks or peeling.
  10.  
  11. Make sure that the timing mark on the camshaft is aligned as described above, and that the timing mark (notch) on the crankshaft sprocket is aligned with the triangular shaped mark on the front housing.
  12.  
  13. Install the tensioner and spring, positioning the tensioner all the way to the intake manifold side and temporarily secure it there with the lockbolt.
  14.  
  15. Install the belt onto the sprockets from YOUR right side. If you are reusing the original belt, make sure you follow the directional mark previously made.
  16.  
  17. Loosen the lockbolt so that the tensioner applies tension to the belt.
  18.  
  19. Turn the crankshaft two full revolutions in the direction of normal rotation. This will apply equal tension to all points of the belt.
  20.  
  21. Make sure that the timing marks are still aligned. If not, repeat the belt installation procedure.
  22.  
  23. Tighten the tensioner lockbolt to 30-35 ft. lbs.
  24.  
  25. Measure the timing belt tension by pressing on the belt at the midpoint of the longest straight run. Belt deflection should be 11-13mm (0.433-0.510 in.). If not, repeat the belt adjustment procedure, above.
  26.  
  27. Install the upper, then the lower, belt covers. Torque to 80 in. lbs.
  28.  
  29. Install the crankshaft pulley and baffle plate.
  30.  
  31. If so equipped, install the power steering pump drive belt.
  32.  
  33. If so equipped, install the air conditioning compressor drive belt.
  34.  
  35. Install the fan pulley, hub and bracket. Torque the fan bracket to 40 ft. lbs.
  36.  
  37. Connect the air injection pipes.
  38.  
  39. Install the alternator.
  40.  
  41. Install the exhaust manifold. Torque to 16-21 ft. lbs.
  42.  
  43. Install the intake manifold and carburetor as an assembly. Torque the intake manifold to 14-19 ft. lbs.
  44.  
  45. Install the spark plugs. Torque to 11-17 ft. lbs.
  46.  
  47. Install the distributor.
  48.  
  49. Install the distributor cap.
  50.  
  51. Install the emissions canister.
  52.  
  53. Install the duty solenoid valves.
  54.  
  55. Install the 3-way solenoid valves.
  56.  
  57. Connect, all wires, hoses, cables, pipes and linkage at the cylinder head.
  58.  
  59. Install the air cleaner.
  60.  
  61. Install the hood.
  62.  
  63. Fill the cooling system.
  64.  

When installing the drive belts on the various accessories, check the belt deflection as follows:



Alternator
 

New: 7-8mm (0.276-0.315 in.) Used: 8-9mm (0.315-0.354 in.)



Power steering pump
 

New: 8-12mm (0.315-0.476 in.) Used: 11-13mm (0.433-0.510 in.)



Air conditioning compressor
 

New: 10-12mm (0.394-0.476 in.) Used: 12-14mm (0.476-0.552 in.) 2,209cc Diesel Engine

The engine must be cold before proceeding.

See Figure 49

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Fig. Fig. 49: Diesel engine cylinder head bolt tightening (torque) sequence

  1. Drain the cooling system.
  2.  
  3. Scribe alignment marks around the hood hinges and remove the hood.
  4.  


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

  1. Remove the air cleaner.
  2.  
  3. Disconnect, and tag, all wires, hoses, cables, pipes and linkage from the cylinder head.
  4.  
  5. Remove the injection lines and injectors. See Fuel System .
  6.  
  7. Remove the intake and exhaust manifolds.
  8.  
  9. Dismount the alternator and move it out of the way.
  10.  
  11. Remove the rocker arm cover. Remove the rocker arm assembly and lift out the pushrods, keeping them in order for proper installation.
  12.  
  13. Remove the cylinder head bolts and, with the aid of an assistant, lift off the head.
  14.  
  15. Make sure that the mating surfaces of the head and block are absolutely clean. Use a new head gasket.
  16.  

To install:
  1. Install the cylinder head.
  2.  
  3. Install the cylinder head bolts. Tighten the head bolts, in the order shown, to 80-85 ft. lbs., in three equal steps.
  4.  
  5. Install the pushrods. When inserting the pushrods, make certain that they bottom in the depressed part of the tappet.
  6.  
  7. Install the rocker arm assembly.
  8.  
  9. Install the rocker arm cover. Torque the rocker cover bolts to 24-36 inch lbs.
  10.  
  11. Install the alternator.
  12.  
  13. Install the intake and exhaust manifolds.
  14.  
  15. Install the injection lines and injectors. See Fuel System .
  16.  
  17. Connect all wires, hoses, cables, pipes and linkage at the cylinder head.
  18.  
  19. Install the air cleaner.
  20.  
  21. Install the hood.
  22.  
  23. Fill the cooling system.
  24.  

CLEANING AND INSPECTION



  1. With the valves installed to protect the valve seats, remove deposits from the combustion chambers and valve heads with a scraper and a wire brush. Be careful not to damage the cylinder head gasket surface. After the valves are removed, clean the valve guide bores with a valve guide cleaning tool. Using cleaning solvent to remove dirt, grease and other deposits, clean all bolts holes; be sure the oil passage is clean (V6 engines).
  2.  
  3. Remove all deposits from the valves with a fine wire brush or buffing wheel.
  4.  
  5. Inspect the cylinder heads for cracks or excessively burned areas in the exhaust outlet ports.
  6.  
  7. Check the cylinder head for cracks and inspect the gasket surface for burrs and nicks. Replace the head if it is cracked.
  8.  
  9. On cylinder heads that incorporate valve seat inserts, check the inserts for excessive wear, cracks, or looseness.
  10.  

RESURFACING Cylinder Head Flatness



When the cylinder head is removed, check the flatness of the cylinder head gasket surfaces.

  1. Place a straightedge across the gasket surface of the cylinder head. Using feeler gauges, determine the clearance at the center of the straightedge.
  2.  
  3. If warpage exceeds 0.08mm (0.0031 in.) in a 152mm (5.98 in.) span, or 0.15mm (0.0059 in.) (0.20mm [0.00787 in.] for the diesel) over the total length, the cylinder head must be resurfaced.
  4.  
  5. If necessary to refinish the cylinder head gasket surface, do not plane or grind off more than 0.25mm (0.0098 in.) (0.05mm [0.00197 in.] for the diesel) from the original gasket surface.
  6.  

When milling the cylinder heads of V6 engines, the intake manifold mounting position is altered, and must be corrected by milling the manifold flange a proportionate amount. Consult an experienced machinist about this.

 
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