GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Distributor

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For ignition system service not found below, please refer toChapter 2 of this manual.

REMOVAL



See Figures 1 through 5

Except MFI-Turbo
  1. Disconnect the negative battery cable. For the 4.3L (VIN Z) engine, remove the air cleaner and hoses.
  2.  
  3. Tag and disengage the electrical wiring connectors either from the distributor or from the ignition coil, whichever is applicable or easier.
  4.  
  5. Remove the distributor cap (If possible, DO NOT remove the coil or spark plug wires) from the distributor and position it aside. On most 4.3L (VIN Z) engines, it will be necessary to tag and disconnect the coil wire along with the spark plug wires from 1 side (either left or right) of the engine.
  6.  

On non-EST equipped vehicles, disconnect the vacuum hose from the distributor vacuum advance module.

  1. Using a crayon, chalk or a marker, make locating marks (for installation purposes) on the rotor, the distributor housing and the engine. Scribe a mark on the distributor body and the engine block showing their relationship. Mark the distributor housing to show the direction in which the rotor is pointing or otherwise matchmark the rotor with the housing.
  2.  
  3. Loosen and remove the distributor hold-down bolt and clamp, then carefully lift the distributor out of the engine. Note the position of the rotor alignment mark on the housing and make a second mark on the housing to align with the rotor.
  4.  



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Fig. Fig. 1: Disengage the ignition module wiring



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Fig. Fig. 2: Matchmark the rotor to the distributor housing



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Fig. Fig. 3: On non-EST distributors, disengage the vacuum hose from the distributor



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Fig. Fig. 4: Remove the distributor hold-down bolt and clamp



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Fig. Fig. 5: Remove the distributor by lifting and tilting until there is sufficient clearance

4.3L MFI-Turbo
  1. Disconnect the negative battery cable.
  2.  
  3. Properly drain the charge air cooler radiator.
  4.  
  5. Loosen the charge air cooler clamps, then remove the ducts and hoses.
  6.  
  7. Remove the charge air cooler.
  8.  
  9. Detach the upper intake manifold connectors and hoses.
  10.  
  11. Unfasten the bolts from the upper intake manifold, then remove the manifold.
  12.  
  13. Disconnect the two screws on the sides of the distributor cap.
  14.  
  15. Tag and disconnect the coil wire along with the spark plug wires from 1 side (either left or right) of the engine.
  16.  
  17. Remove the distributor cap and position it aside.
  18.  
  19. Using a crayon, chalk or a marker, make locating marks (for installation purposes) on the rotor, the distributor housing and the engine. Scribe a mark on the distributor body and the engine block showing their relationship. Mark the distributor housing to show the direction in which the rotor is pointing or otherwise matchmark the rotor with the housing.
  20.  
  21. Loosen the remove the distributor hold-down bolt, washer and clamp, then carefully lift the distributor out of the housing and make a second mark on the housing to align with the rotor.
  22.  

INSTALLATION



Undisturbed Engine
EXCEPT MFI-TURBO

This condition exists if the engine has not been rotated while the distributor was removed.

  1. With a new O-ring on the distributor housing and the rotor aligned with the second mark on the housing, install the distributor, taking care to align the distributor body mark with the mark scribed on the engine. When fully installed, the rotor should turn and align with the first distributor housing mark and therefore point in the same direction as before removal. It may be necessary to lift the distributor and turn the rotor slightly to properly align the gears and the oil pump driveshaft.
  2.  
  3. With the respective marks aligned, install the hold-down clamp and bolt finger-tight.
  4.  
  5. If equipped, connect the vacuum hose to the distributor vacuum advance module.
  6.  
  7. Install and secure the distributor cap.
  8.  
  9. Engage the electrical connector(s) to the distributor or coil, as applicable.
  10.  
  11. If removed, connect the spark plug and coil wires as noted during removal.
  12.  
  13. Connect a timing light to the engine (following the manufacturer's instructions) and connect the negative battery cable. Start the engine, then check and adjust the timing, as necessary.
  14.  

If removed, be sure to install the air cleaner and hoses.

  1. Turn the engine OFF and tighten the distributor clamp bolt.
  2.  
  3. Start the engine and recheck the timing to verify it did not change while tightening the hold-down bolt, then stop the engine and remove the timing light.
  4.  

4.3L MFI-TURBO
  1. With a new O-ring on the distributor housing and the rotor aligned with the second housing mark, install the distributor, taking care to align the distributor body mark with the mark scribed on the engine. When fully installed, the rotor should turn and align with the first distributor mark and therefore point in the same direction as before removal. It may be necessary to lift the distributor and turn the rotor slightly to properly align the gears and the oil pump driveshaft.
  2.  
  3. With the marks aligned, install the hold-down clamp, washer and bolt. Tighten the bolt to 20 ft. lbs. (27 Nm).
  4.  
  5. Install and secure the distributor cap.
  6.  
  7. Connect the spark plug coil wires as noted during removal.
  8.  
  9. Install the upper intake manifold and tighten the bolts to 17 ft. lbs. (23 Nm).
  10.  
  11. Install the throttle body, cable bracket and bolts and tighten to 17 ft. lbs. (23 Nm).
  12.  
  13. Attach the upper intake manifold connectors and hoses.
  14.  
  15. Install the charge air cooler, then connect the cooler hoses and clamps.
  16.  
  17. Connect the negative battery cable.
  18.  
  19. Properly refill the charge air cooling system.
  20.  
  21. Connect a timing light to the engine (following the manufacturer's instructions). Start the engine, then check and adjust the timing as necessary. Turn the engine OFF and remove the timing light.
  22.  

Disturbed Engine

This condition exists when the engine has been rotated with the distributor removed.

  1. Install a new O-ring on the distributor housing.
  2.  
  3. Rotate the crankshaft to position the No. 1 cylinder on the TDC of it's compression stroke. This may be determined by inserting a rag into the No. 1 spark plug hole and slowly turn the engine crankshaft. When the timing mark on the crankshaft pulley aligns with the 0° mark on the timing scale and the rag is blown out by the compression, the No. 1 piston is at top-dead-center (TDC).
  4.  

If you are unsure when TDC is reached, remove the valve cover and watch the rocker arms for the No. 1 cylinder. If the valves move as the crankshaft timing marker approaches the scale, the No. 1 cylinder is on its exhaust stroke. If the valves remain closed as the timing mark approaches the scale, then the No. 1 cylinder is approaching TDC of the compression stroke.

  1. Turn the rotor so that it will point to the No. 1 terminal of the distributor cap.
  2.  
  3. Install the distributor into the engine block. It may be necessary to turn the rotor, a little in either direction, in order to engage the gears.
  4.  
  5. Tap the starter a few times to ensure that the oil pump shaft is mated to the distributor shaft.
  6.  
  7. Bring the engine to No. 1 TDC again and check to see that the rotor is indeed pointing toward the No. 1 terminal of the cap.
  8.  
  9. With the respective marks aligned, install the hold-down clamp and bolt finger-tight.
  10.  
  11. Install and secure the distributor cap.
  12.  
  13. Engage the electrical connector(s) to the distributor and, if equipped, the vacuum advance hose.
  14.  
  15. If removed, connect the spark plug and coil wires as noted during removal.
  16.  
  17. Connect a timing light to the engine (following the manufacturer's instructions) and connect the negative battery cable. Start the engine, then check and adjust the timing, as necessary.
  18.  

If removed, be sure to install the air cleaner and hoses.

  1. Turn the engine OFF and tighten the distributor clamp bolt.
  2.  
  3. Start the engine and recheck the timing to verify it did not change while tightening the hold-down bolt, then stop the engine and remove the timing light.
  4.  

 
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