Mazda Trucks 1987-1993 Repair Guide

Balance (Countershafts) Shafts

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REMOVAL AND INSTALLATION



The 2.6L (1987-88) and 2.6L (1989-93) engines use two countershafts (silent shafts) in the cylinder block to reduce engine noise and vibration.

2.6L Engine (1987-88)

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Balancer chain and and sprocket alignment

The following procedures are to be performed with engine removed from vehicle.

  1. Disconnect the battery ground (negative) cable. Drain the coolant. Disconnect and remove the radiator hoses. Remove the radiator.
  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 alternator and accessory belts.
  2.  
  3. Rotate the crankshaft to bring No.1 piston to TDC, on the compression stroke.
  4.  
  5. Mark and remove the distributor.
  6.  
  7. Remove the crankshaft pulley.
  8.  
  9. Remove the water pump assembly.
  10.  
  11. Remove the cylinder head (See cylinder head removal section).
  12.  

It may be possible to replace the timing chain without removing the cylinder head, however removing the head will make the job easier.

  1. Raise the front of the truck and support it safely on jackstands.
  2.  
  3. Drain the engine oil and remove the oil pan and screen.
  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. Remove the timing case cover.
  2.  
  3. Remove the chain guides, Side (A), Top (B), Bottom (C), from the B chain (outer). See illustration.
  4.  
  5. Remove the locking bolts from the B chain sprockets.
  6.  
  7. Remove the crankshaft sprocket, counterbalance shaft sprocket and the outer chain.
  8.  
  9. Remove the crankshaft and camshaft sprockets and the A (inner) chain.
  10.  
  11. Remove the camshaft sprocket holder and the chain guides, both left and right. Remove the tensioner spring and sleeve from the oil pump.
  12.  

For further service to shafts and oil pump follow step 16 and 17.

  1. Remove the oil pump by first removing the bolt locking the oil pump driven gear and the right counterbalance shaft, and then remove the oil pump mounting bolts. Remove the counterbalance shaft from the engine block.
  2.  

If the bolt locking the oil pump driven gear and the counterbalance shaft is hard to loosen, remove the oil pump and the shaft as a unit.

  1. Remove the left silent shaft thrust plate by screwing two 8mm screws into tapped holes in thrust plate. Remove left silent shaft.
  2.  

If the tensioner rubber nose, or chain guide show wear, they should be replaced.

Silent shaft clearance specifications are the following:



Outer diameter to outer bearing clearance: 0.02-0.06mm (0.000787-0.00236 in.)
 
Inner diameter to inner bearing clearance: 0.05-0.09mm (0.00197-0.00354 in.)
 

To install:
  1. Install the right counterbalance shaft into the engine block if removed.
  2.  
  3. Install the oil pump assembly if removed. Do not lose the woodruff key from the end of the counterbalance shaft. Torque the oil pump mounting bolts to 6 to 7 ft. lbs.
  4.  
  5. If they have been removed tighten the counterbalance shaft and the oil pump driven gear mounting bolts.
  6.  

The counterbalance shaft and the oil pump can be installed as a unit, if necessary.

  1. Install the left counterbalance shaft into the engine block if removed.
  2.  
  3. Install a new O-ring on the thrust plate and install the unit into the engine block, using a pair of bolts without heads, as alignment guides.
  4.  

If the thrust plate is turned to align the bolts holes, the O-ring may be damaged.

  1. Remove the guide bolts and install the regular bolts into the thrust plate and tighten securely.
  2.  
  3. Rotate the crankshaft to bring No. 1 piston to TDC.
  4.  
  5. Using a new head gasket install the cylinder head.
  6.  
  7. Install the sprocket holder and the right and left chain guides.
  8.  
  9. Install the tensioner spring and sleeve on the oil pump body.
  10.  
  11. Install the camshaft and crankshaft sprockets on the timing chain, aligning the sprocket punch marks to the plate chain links.
  12.  
  13. While holding the sprocket and chain as a unit, install the crankshaft sprocket over the crankshaft and align it with the keyway.
  14.  
  15. Keeping the dowel pin hole on the camshaft in a vertical position, install the camshaft sprocket and chain on the camshaft.
  16.  

The sprocket timing mark and the plated chain link should be at the 2 to 3 o'clock position when correctly installed. The chain must be aligned in the right and left chain guides with the tensioner pushing against the chain. The tension for the inner chain is predetermined by spring tension.

  1. Install the crankshaft sprocket for the outer or B chain.
  2.  
  3. Install the two counterbalance shaft sprockets and align the punched mating marks with the plated linds of the chain.
  4.  
  5. Holding the two shaft sprockets and chain, install the outer chain in alignment with the mark on the crankshaft sprocket. Install the shaft sprockets on the counterbalance shaft and the oil pump driver gear. Install the lock bolts and recheck the alignment of the punch marks and the plated links.
  6.  
  7. Temporarily install the chain guides: Side (A), Top (B), and Bottom (C).
  8.  
  9. Tighten Side (A), chain guide securely.
  10.  
  11. Tighten Bottom (B) chain guide securely.
  12.  
  13. Adjust the position of the Top (B) chain guide, after shaking the right and left sprockets to collect any chain slack, so that when the chain is moved toward the center, the clearance between the chain guide anmd the chain links will be approximately 3.5mm (0.13779 in.). Tighten the Top (B) chain guide bolts.
  14.  
  15. Install the timing chain cover using a new gasket. being careful not to damage the front seal.
  16.  
  17. Install the oil screen and the oil pan, using a new gasket. Torque the bolts to 54-66 in. lbs. (6-7 Nm).
  18.  
  19. Install the crankshaft pulley, alternator and accessory belts, and the distributor.
  20.  
  21. Install the oil pressure switch, if removed, and install the battery ground cable.
  22.  
  23. Install the fan blades, radiator, fill the system with coolant and start the engine.
  24.  

2.6L Engine (1989-93)

See Figures 2 and 3

  1. Disconnect the battery ground.
  2.  
  3. Drain the cooling system.
  4.  


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 accessory drive belts.
  2.  
  3. Remove the fan and shroud.
  4.  
  5. Remove the water pump pulley.
  6.  
  7. Unbolt and remove the water pump.
  8.  
  9. Remove the crankshaft pulley.
  10.  
  11. Remove the oil pan.
  12.  
  13. Remove the timing chain cover.
  14.  
  15. Remove the oil pick-up tube.
  16.  
  17. Remove and discard the water inlet pipe gasket.
  18.  
  19. Remove the crankshaft sprocket spacer.
  20.  
  21. Remove the idler sprocket lockbolt.
  22.  
  23. Remove chain guide A .
  24.  
  25. Remove chain guide B .
  26.  
  27. Remove chain guide C .
  28.  
  29. Remove the idler sprocket and crankshaft sprocket bolts and pull off the sprockets along with the balancer chain.
  30.  
  31. Remove the left balance shaft.
  32.  
  33. Remove the right balance shaft.
  34.  
  35. Remove the crankshaft timing gear bolt.
  36.  
  37. Remove the timing chain tensioner.
  38.  
  39. Pull the timing chain and sprockets off.
  40.  
  41. Remove the chain guide and lever.
  42.  

To install:
  1. Install the chain guide and lever. Torque the chain guide bolts to 78 in. lbs. (9 Nm); the lever bolts to 95 in. lbs. (11 Nm). Make sure that the lever moves smoothly.
  2.  
  3. Install the chain adjuster. Torque the bolts to 95 in. lbs. (11 Nm). Move the adjuster sleeve towards the left and install a pin to hold it in place.
  4.  
  5. Install the timing gear sprocket and chain. With the timing mark on the sprocket at the 6 o'clock position, the white links on the chain should be on either side of the mark.
  6.  
  7. Install the camshaft sprocket on the camshaft with the timing mark at the 3 o'clock position. The white link should align with the mark. Temporarily secure the chain to the sprocket with a piece of wire.
  8.  
  9. Install the balance shafts. Torque the thust plate bolts to 95 in. lbs. (11 Nm).
  10.  
  11. Install the crankshaft sprocket.
  12.  
  13. Install the idler shaft and sprocket.
  14.  
  15. Set the balance chain on the balance shaft sprocket aligns with the brown link on the chain.
  16.  
  17. Install the balancer chain, aligning all the marks as shown.
  18.  
  19. Install chain guides A and B . Torque the bolts to 95 in. lbs. (11 Nm).
  20.  
  21. Install chain guide C . Tighten the bolt to 95 in. lbs. (11 Nm).
  22.  
  23. Torque the idler sprocket lockbolt to 38 ft. lbs. (52 Nm).
  24.  
  25. Install the spacer.
  26.  
  27. Loosen chain guide C adjusting bolt.
  28.  
  29. Push chain guide C with a force of about 10 lb., downward, against the chain, then, pull it back 3.5mm (0.13779 in.) and tighten the bolt to 95 in. lbs. (11 Nm). When properly adjusted, there should be about 3mm (0.1181 in.) of slack in the chain at the mid-point of the guide.
  30.  

If, when applying the downward force on the chain guide, it bottoms against the adjusting bolt, you should replace the balancer chain.

  1. Remove the tensioner adjuster retaining pin.
  2.  
  3. Install a new water inlet pipe gasket using adhesive sealer.
  4.  
  5. Install the oil pick-up tube using a new gasket. Torque the bolts to 95 in. lbs. (11 Nm).
  6.  
  7. Using new gaskets coated with sealer, install the timing chain cover. Torque the bolts to 19 ft. lbs. (26 Nm).
  8.  
  9. Install the camshaft sprocket service cover.
  10.  
  11. Remove the wire from the camshaft sprocket.
  12.  
  13. Tighten the oil pick-up brace bolt to 95 in. lbs. (11 Nm).
  14.  
  15. Install the oil pan. Torque the bolts to 95 in. lbs. (11 Nm).
  16.  
  17. Install the crankshaft pulley. Torque the bolt to 145 ft. lbs. (197 Nm).
  18.  
  19. Install the water pump.
  20.  
  21. Install the water pump pulley.
  22.  
  23. Install the fan and shroud.
  24.  
  25. Install the accessory drive belts.
  26.  
  27. Fill the cooling system.
  28.  
  29. Connect the battery ground.
  30.  



Click image to see an enlarged view

Fig. Fig. 2: Exploded view of the balancer chain and timing chain assemblies



Click image to see an enlarged view

Fig. Fig. 3: Balancer chain and shaft sprocket alignment

 
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