GM Buick/Oldsmobile/Pontiac/Full-Size 1975-1990 Repair Guide

Injectors

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See Figures 1, 2 and 3

REMOVAL & INSTALLATION



1978-79
  1. Disconnect the negative (-) battery cable. Remove the fuel return line from the nozzle as previously outlined under injection lines.
  2.  
  3. Remove the nozzle hold-down clamp and spacer. Then, pull the nozzle out of the cylinder head with tool J-26952 or equivalent.
  4.  
  5. Cap the high pressure line and nozzle tip.
  6.  


WARNING
The nozzle tip is highly susceptible to damage and must be protected at all times.

Click image to see an enlarged view

Fig. Fig. 1: Injector and glow plug location


To install:
  1. If an old nozzle is to be reinstalled, a new compression seal and carbon stop seal must be installed after removal of the used seals.
  2.  
  3. Remove the caps and install the nozzle, spacer and clamp. Torque to 25 ft. lbs. (34 Nm).
  4.  
  5. Install return line.
  6.  
  7. Connect the negative battery cable, start the engine and check for leaks.
  8.  

1980 and Later Models

You will need a means to securely cap off fuel nozzles and lines before disconnecting fuel-containing parts.

  1. Disconnect the negative (-) battery cable.
  2.  
  3. Using a back-up wrench on the upper injection nozzle hex, disconnect the fuel line from the nozzle. Then, cap off both openings to prevent fuel contamination.
  4.  
  5. Using a wrench on the lower, larger nozzle hex, unscrew and remove the nozzle. Look to see if the copper gasket installed under the nozzle remained on the cylinder head. If so, remove it. Failure to do so will cause engine operating problems!
  6.  
  7. Nozzle testing requires specialized equipment, fluids, and training. However, it will be cost-effective for you to remove your own nozzles and have them tested and/or repaired at a diesel specialist. If you replace nozzles, make sure they are color coded with a blue band, meaning they are intended for use with the V8.
  8.  

To install:


Click image to see an enlarged view

Fig. Fig. 2: Removing the old sealing washer

  1. If the sealing washer remained on the nozzle tip, use diagonal cutters to force it off. Be careful not to squeeze the cutters to the point where they scratch the nozzle tip. Use them only to pry the washer loose. Clean the nozzle tip thoroughly with a safe solvent. Install a new copper washer and, if it will not stay on the tip, crimp it slightly so it will stay in place as you install the nozzle.
  2.  
  3. Remove protective caps. Install the nozzle by screwing it in, and then, using the largest hex, torque it to 25 ft. lbs. (34 Nm).
  4.  
  5. Connect the high pressure line and, using a back-up wrench on the upper nozzle hex, tighten the high pressure line fitting to 25 ft. lbs. (34 Nm).
  6.  
  7. Connect the negative battery cable, start the engine and check for leaks.
  8.  



Click image to see an enlarged view

Fig. Fig. 3: Disassembled diesel injector

 
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