Mazda Trucks 1987-1993 Repair Guide

Camshaft

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REMOVAL AND INSTALLATION



2.2L Engine

See Figure 1

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Drain the cooling system.
  6.  


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 front cover assembly.
  2.  
  3. Remove the cam gear.
  4.  
  5. Remove the thermostat housing.
  6.  
  7. Remove the distributor assembly.
  8.  
  9. Remove the rocker cover.
  10.  
  11. Remove the rear housing.
  12.  
  13. Remove the rocker arm assembly.
  14.  
  15. If equipped, remove the thrust plate.
  16.  
  17. Remove the camshaft from the cylinder head.
  18.  



Click image to see an enlarged view

Fig. Fig. 1: Camshaft and cylinder head components

To install:
  1. Coat the camshaft with clean engine oil and position it on the cylinder head.
  2.  
  3. Install the thrust plate and new gasket.
  4.  
  5. Install the rocker arm assembly.
  6.  
  7. Install the rear housing and new gasket.
  8.  
  9. Install the rocker cover and new gasket.
  10.  
  11. Install the distributor assembly.
  12.  
  13. Install the thermostat housing and new gasket.
  14.  
  15. Install the cam gear.
  16.  
  17. Install the front cover assembly.
  18.  
  19. Fill the cooling system.
  20.  
  21. Install the air cleaner assembly.
  22.  
  23. Connect the negative battery cable.
  24.  

2.6L Engine (1987-88)

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Remove the rocker arm/valve cover.
  6.  
  7. Remove the water pump belt and pulley.
  8.  
  9. Rotate the crankshaft until number 1 piston is at the top of its compression stroke (both valves closed).
  10.  
  11. Record the position of mating mark on camshaft sprocket and plated link on timing chain.
  12.  
  13. Remove the camshaft sprocket bolt, washer and distributor drive gear.
  14.  
  15. Remove the timing chain and camshaft sprocket assembly and lay aside.
  16.  
  17. Remove the rocker arms/shafts assembly.
  18.  
  19. Carefully remove camshaft without cocking to prevent damage to cam.
  20.  



Click image to see an enlarged view

Fig. Fig. 2: Camshaft and cylinder head components

To install:
  1. Lubricate the camshaft and set in place.
  2.  
  3. Install the rocker arms/shafts assembly.
  4.  
  5. With the rocker arms/shafts assembly and bearing caps torqued down, rotate the camshaft so that dowel hole is on vertical centerline of cylinder head.
  6.  
  7. Install the timing chain and camshaft sprocket assembly. Make sure mating mark on camshaft sprocket and plated link on timing chain are lined up.
  8.  
  9. Install the distributor drive gear, washer and camshaft sprocket bolt. Tighten the bolt to 40 ft. lbs. (54 Nm).
  10.  
  11. Install the water pump pulley and belt.
  12.  

After servicing rocker shaft assembly, Jet Valve Clearance (if used) adjustment must be performed. See Valve Adjusting Procedure.

  1. Install the rocker arm/valve cover.
  2.  
  3. Install the air cleaner assembly.
  4.  
  5. Connect the negative battery cable.
  6.  

2.6L Engine (1989-93)

See Figure 2

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the air cleaner assembly.
  4.  
  5. Remove the rocker arm/valve cover.
  6.  
  7. Rotate the crankshaft until number 1 piston is at the top of its compression stroke (both valves closed).
  8.  
  9. Remove the distributor drive gear.
  10.  
  11. Record the position of mating mark on camshaft sprocket and plated link on timing chain.
  12.  
  13. Remove the camshaft sprocket service cover.
  14.  
  15. Push the chain adjuster sleeve towards the left and insert a 2mm (0.0787 inch) diameter by 47mm (1.85 inch) long pin in the lever hole to hold the adjuster.
  16.  
  17. Wire the camshaft sprocket and timing chain together and remove the timing chain and camshaft sprocket assembly from the camshaft, and lay aside.
  18.  
  19. Remove the rocker arms/shafts assembly.
  20.  
  21. Remove the cover end seals.
  22.  
  23. Carefully remove camshaft without cocking to prevent damage to cam.
  24.  

To install:
  1. Lubricate the camshaft and set in place.
  2.  
  3. Coat the end seal with RTV silicone gasket mater and install them in their recesses.
  4.  
  5. Install the rocker arms/shafts assembly.
  6.  
  7. With the rocker arms/shafts assembly and bearing caps torqued down, rotate the camshaft so that dowel pin is on the top center of cylinder head.
  8.  
  9. Install the timing chain and camshaft sprocket assembly. Make sure that the timing mark and the white link align. Removing the wire.
  10.  
  11. Install the distributor drive gear, a new washer, and the lockbolt. Hold the crankshaft to keep it from turning and tighten the lockbolt to 45 ft. lbs. (61 Nm).
  12.  
  13. Release the chain adjuster.
  14.  
  15. Install the service cover. Tighten the bolt to 95 inch lbs.(11 Nm); the nut to 87 inch lbs. (10 Nm).
  16.  
  17. Install the valve cover.
  18.  
  19. Install the air cleaner assembly.
  20.  
  21. Connect the negative battery cable.
  22.  

3.0L Engine

See Figure 3

  1. Remove the cylinder heads from the vehicle as described in this information.
  2.  
  3. Engage the camshaft sprocket with a suitable spanner wrench type holding tool and loosen the retaining bolt. Pull the sprocket from the end of the camshaft.
  4.  
  5. Insert the blade of a flat tipped screwdriver between the camshaft oil seal and gently pry the seal from the cylinder head bore. Be careful not to damage the seal bore. Discard the seal and purchase a new one.
  6.  
  7. Remove the rocker arm and shaft assemblies.
  8.  

Do not remove the hydraulic lach adjusters unless it is absolutely necessary to do so. The lash adjusters are sealed in the rocker arms by an O-ring. If this O-ring is disturbed or damaged, the lash adjusters may leak. If they are removed, make sure that a new O-ring(s) is installed and that the oil reservoirs in the rocker arms are filled with clean engine oil.

  1. Before removing the camshaft thrust plate, proceed to the inspection information to measure the camshaft endplay. This will determine if the thrust plate or the camshaft have to be replaced.
  2.  
  3. Remove the thrust plate and slowly and carefully withdraw the camshaft from the cylinder head. Clean off the lobe and journal surfaces and proceed to the insection information.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: Camshaft and cylinder head components

To install:
  1. Apply a liberal coating of clean engine oil to the surfaces of the cam lobes, bearing and journal surfaces. Slowly and carefully insert the camshaft into the cylinder head. Install the camsahft thrust plate and torque the retaining bolt to 6-8 ft. lbs. (8-11 Nm).
  2.  
  3. Wipe down the surface of the seal bore with a clean rag and coat the lip of the new oil seal with clean engine oil. Install the seal into the cylinder head using a socket or a length of pipe that closely approximates the diameter of the seal as an installation tool. Tap the seal evenly into the seal bore.
  4.  
  5. Install the rockerarm/shaft assembly.
  6.  
  7. Complete the installation of the cylinder head by reversing the removal procedure.
  8.  

4.0L Engine

See Figure 4

Review the complete service procedure before starting this repair. Refer to the necessary service procedures in this Chapter.

  1. Disconnect the negative battery cable.
  2.  
  3. Drain the engine oil into a suitable container and dispose of it properly.
  4.  


CAUTION
The EPA warns that prolonged contact with used engine oil may cause a number of skin disorders, including cancer! You should make every effort to minimize your exposure to used engine oil. Protective gloves should be worn when changing the oil. Wash your hands and any other exposed skin areas as soon as possible after exposure to used engine oil. Soap and water, or waterless hand cleaner should be used.

  1. Drain the cooling system.
  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 radiator.
  2.  
  3. Remove the condenser.
  4.  
  5. Remove the cooling fan and shroud.
  6.  
  7. Remove the air cleaner hoses.
  8.  
  9. Tag and remove the spark plug wires.
  10.  
  11. Remove the EDIS ignition coil and bracket.
  12.  
  13. Remove the crankshaft pulley/damper.
  14.  
  15. Remove the clamp. bolt and oil pump drive from the rear of the block.
  16.  
  17. Remove the alternator.
  18.  
  19. Relieve the fuel system pressure.
  20.  
  21. Remove the fuel lines at the fuel supply manifold.
  22.  
  23. Remove the intake manifold assembly.
  24.  
  25. Remove the rocker arm covers.
  26.  
  27. Remove the rocker arm/shaft assemblies.
  28.  
  29. Remove the pushrods. Identify them for installation. They must be installed in their original positions!
  30.  
  31. Remove the tappets. Identify them for installation.
  32.  
  33. Remove the oil pan.
  34.  
  35. Remove the engine front cover and water pump.
  36.  
  37. Place the timing chain tensioner in the retracted position and install the retaining clip.
  38.  
  39. Turn the engine by hand until the timing marks align at TDC of the power stroke on No.1 piston.
  40.  
  41. Check the camshaft endplay. If excessive, you'll have to replace the thrust plate.
  42.  
  43. Remove the camshaft gear attaching bolt and washer, then slide the gear off the camshaft.
  44.  
  45. Remove the camshaft thrust plate.
  46.  
  47. Carefully slide the camshaft out of the engine block, using caution to avoid any damage to the camshaft bearings.
  48.  



Click image to see an enlarged view

Fig. Fig. 4: Camshaft removal/installation

To install:
  1. Oil the camshaft journals and cam lobes with heavy SG engine oil (50W).
  2.  
  3. Install the camshaft in the block, using caution to avoid any damage to the camshaft bearings.
  4.  
  5. Install the thrust plate. Make sure that it covers the main oil gallery. Tighten the attaching screws to 7-10 ft. lbs. (9-13 Nm).
  6.  
  7. Rotate the camshaft and crankshaft as necessary to align the timing marks. Install the camshaft gear and chain. Tighten the attaching bolt to 50 ft. lbs. (68 Nm).
  8.  
  9. Remove the clip from the chain tensioner.
  10.  
  11. Install the engine front cover and water pump assembly. Refer to the necessary service procedures in this Chapter.
  12.  
  13. Install the crankshaft damper/pulley.
  14.  
  15. Install the oil pan.
  16.  
  17. Coat the tappets with 50W engine oil and place them in their original locations.
  18.  
  19. Apply 50W engine oil to both ends of the pushrods. Install the pushrods in their original locations.
  20.  
  21. Install the intake manifold assembly.
  22.  
  23. Install the rocker arm/shaft assemblies.
  24.  
  25. Install the rocker covers.
  26.  
  27. Install the cooling fan.
  28.  
  29. Install the fuel lines.
  30.  
  31. Install the oil pump drive.
  32.  
  33. Install the alternator.
  34.  
  35. Install the EDIS coil and plug wires. Coat the inside of each wire boot with silicone lubricant.
  36.  
  37. Install the radiator and condenser.
  38.  
  39. Refill the cooling system.
  40.  
  41. Replace the oil filter and refill the crankcase with the specified amount of engine oil.
  42.  
  43. Reconnect the battery ground cable.
  44.  
  45. Start the engine and check the ignition timing and idle speed. Adjust if necessary. Run the engine at fast idle and check for coolant, fuel, vacuum or oil leaks.
  46.  

INSPECTION



Camshaft Lobe Lift
2.2L, 2.6L and 3.0L ENGINES

See Figure 5

Check the lift of each lobe in consecutive order and make a note of the readings. Camshaft assembly specifications are sometimes modified by Mazda after production. Refer to a local reputable machine shop as necessary.

  1. Remove the valve cover.
  2.  
  3. Measure the distance between the major (A-A) and minor (B-B) diameters of each cam lobe with a Vernier caliper and record the readings. The difference in the readings on each cam diameter is the lobe lift.
  4.  
  5. If the readings do not meet specifications, replace the camshaft and all rocker arms/cam followers.
  6.  
  7. Install the valve cover.
  8.  



Click image to see an enlarged view

Fig. Fig. 5: Camshaft lobe height measurements

4.0L ENGINE

See Figures 5 and 6

Check the lift of each lobe in consecutive order and make a note of the reading. Camshaft assembly specifications are sometimes modify by Ford after production. Refer to a local reputable machine shop as necessary.

  1. Remove the fresh air inlet tube and the air cleaner. Remove the heater hose and crankcase ventilation hoses. Remove valve rocker arm cover(s).
  2.  
  3. Remove the rocker arm stud nut or fulcrum bolts, fulcrum seat and rocker arm.
  4.  



Click image to see an enlarged view

Fig. Fig. 6: Using a dial indicator to measure camshaft lobe lift

  1. Make sure the push rod is in the valve tappet socket. Install a dial indicator D78P-4201-B (or equivalent) so that the actuating point of the indicator is in the push rod socket (or the indicator ball socket adapter Tool 6565-AB is on the end of the push rod) and in the same plane as the push rod movement.
  2.  
  3. Disconnect the I terminal and the S terminal at the starter relay. Install an auxiliary starter switch between the battery and S terminals of the starter relay. Crank the engine with the ignition switch off. Turn the crankshaft over until the tappet is on the base circle of the camshaft lobe. At this position, the push rod will be in its lowest position.
  4.  
  5. Zero the dial indicator. Continue to rotate the crankshaft slowly until the push rod is in the fully raised position.
  6.  
  7. Compare the total lift recorded on the dial indicator with the specification.To check the accuracy of the original indicator reading, continue to rotate the crankshaft until the indicator reads zero. If the lift on any lobe is below specified wear limits, the camshaft and the valve tappet operating on the worn lobe(s) must be replaced.
  8.  
  9. Remove the dial indicator and auxiliary starter switch.
  10.  
  11. Install the rocker arm, fulcrum seat and stud nut or fulcrum bolts. Check the valve clearance. Adjust if required (refer to (see Distributor Ignition System of this guide).
  12.  
  13. Install the valve rocker arm covers and the air cleaner.
  14.  

Camshaft End Play

2.2L, 2.6L AND 3.0L ENGINES

See Figure 7

On engines with an aluminum or nylon camshaft sprocket, prying against the sprocket, with the valve train load on the camshaft, can break or damage the sprocket. Therefore, the rocker arm adjusting nuts must be backed off, or the rocker arm and shaft assembly must be loosened sufficiently to free the camshaft. After checking the camshaft end play, check the valve clearance. Adjust if required (refer to procedure in this information).



Click image to see an enlarged view

Fig. Fig. 7: Performing the camshaft end play procedure

  1. Push the camshaft toward the rear of the engine. Install a dial indicator so that the indicator point is on the camshaft sprocket attaching screw.
  2.  
  3. Zero the dial indicator. Position a prybar between the camshaft gear and the block. Pull the camshaft forward and release it. Compare the dial indicator reading with the specifications.
  4.  
  5. If the end play is excessive, check the spacer for correct installation before it is removed. If the spacer is correctly installed, replace the thrust plate.
  6.  
  7. Remove the dial indicator.
  8.  

4.0L ENGINES

See Figure 8

  1. Push the camshaft toward the rear of the engine. Install a dial indicator (Tool D78P-4201-C or equivalent so that the indicator point is on the camshaft sprocket attaching screw.
  2.  



Click image to see an enlarged view

Fig. Fig. 8: Performing the camshaft end play procedure

  1. Zero the dial indicator. Position a prybar between the camshaft gear and the block. Pull the camshaft forward and release it. Compare the dial indicator reading with the specification. The camshaft endplay specification is 0.0008-0.004 inch and the service limit is 0.009 inch (0.007 inch on 3.0L engine). Camshaft specifications are sometimes modified by the manufacturer after production.
  2.  
  3. If the end play is excessive, check the spacer for correct installation before it is removed. If the spacer is correctly installed, replace the thrust plate.
  4.  

The spacer ring and thrust plate are available in two thicknesses to permit adjusting the end play.

  1. Remove the dial indicator.
  2.  

 
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