GM Full-Size Trucks 1980-1987 Repair Guide

Engine

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REMOVAL & INSTALLATION



The factory recommended procedure for engine removal is to remove the engine/transmission as a unit on two wheel drive models, except for the diesel. Only the engine should be removed on diesels and four wheel drive models.

  1. Disconnect the negative battery terminal. On diesels, disconnect the negative cables at the batteries and ground wires at the inner fender panel.
  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. Drain the engine oil.
  2.  
  3. Remove the air cleaner and ducts.
  4.  
  5. Scribe alignment marks around the hood hinges, and remove the hood.
  6.  
  7. Remove the radiator and hoses, and the fan shroud if so equipped.
  8.  
  9. Disconnect and label the wires at:
    1. Starter solenoid.
    2.  
    3. Alternator.
    4.  
    5. Temperature switch.
    6.  
    7. Oil pressure switch.
    8.  
    9. Transmission controlled spark solenoid.
    10.  
    11. CEC solenoid.
    12.  
    13. Coil.
    14.  
    15. Neutral safety switch.
    16.  

  10.  
  11. Disconnect:
    1. Accelerator linkage (hairpin at bellcrank, throttle and T.V. cables at intake manifold brackets on diesels.) Position away from the engine.
    2.  
    3. Choke cable at carburetor, if so equipped.
    4.  
    5. Release the fuel system pressure (see Routine Maintenance ) and disconnect the fuel line to fuel pump.
    6.  
    7. Heater hoses at engine.
    8.  
    9. Air conditioning compressor with hoses attached. Do not remove the hoses from the air conditioning compressor. Remove it as a unit and set it aside. Its contents are under pressure, and can freeze body tissue on contact.
    10.  

  12.  

R-12 refrigerant is a chlorofluorocarbon which, when released into the atmosphere, can contribute to the depletion of the ozone layer in the upper atmosphere. Ozone filters out harmful radiation from the sun. If possible, an approved R-12 Recovery/Recycling machine that meets SAE standards should be employed when discharging the system. Follow the operating instructions provided with the equipment exactly to properly discharge the system.

  1. Loosen and remove the fan belt, remove the fan blades and pulley. If you have the finned aluminum viscous drive fan clutch, keep it upright in its normal position. If the fluid leaks out, the unit will have to be replaced.
  2.  
  3. Remove the clutch cross-shaft.
  4.  
  5. Attach a lifting device to the engine. You may have to remove the carburetor. Take the engine weight off the engine mounts, and unbolt the mounts. On all models except the gas engine 1 /2 and 3 /4 ton, support and disconnect the transmission. With automatic transmission, remove the torque converter underpan and starter, unbolt the converter from the flywheel, detach the throttle linkage and vacuum modulator line, and unbolt the engine from the transmission. Be certain that the converter does not fall out. With manual transmission, unbolt the clutch housing from the engine. Further details are in Drive Train .
  6.  
  7. On two wheel drive models, remove the driveshaft. See details in Drive Train . Either drain the transmission or plug the driveshaft opening. Disconnect the speedometer cable at the transmission. Disconnect the TCS switch wire, if so equipped. Disconnect the shift linkage or lever, or the clutch linkage. Disconnect the transmission cooler lines, if so equipped. If you have an automatic or a four speed transmission, the rear crossmember must be removed. With the three speed, unbolt the transmission from the crossmember. Raise the engine/transmission assembly and pull it forward.
  8.  
  9. On diesels, remove the three bolts, transmission, right side; disconnect the wires to the starter and remove the starter.
  10.  
  11. On four wheel drive, raise and pull the engine forward until it is free of the transmission. On diesels, slightly raise the transmission, remove the three left transmission to engine bolts, and remove the engine.
  12.  
  13. On all trucks, lift the engine out slowly, making certain as you go that all lines between the engine and the truck have been disconnected.
  14.  

To install:
  1. On four wheel drive and diesels, lower the engine into place and align it with the transmission. Push the engine back gently and turn the crankshaft until the manual transmission shaft and clutch engage. Bolt the transmission to the engine. With automatic transmission, align the converter with the flywheel, bolt the transmission to the engine, bolt the converter to the flywheel, replace the underpan and starter, and connect the throttle linkage and vacuum modulator line. See Drive Train for details.
  2.  
  3. On two wheel drive, lower the engine/transmission unit into place. Replace the rear crossmember if removed. Bolt the three speed transmission back to the crossmember. Replace the driveshaft.
  4.  
  5. Install the engine mounts.
  6.  
  7. Replace all transmission connections and the clutch cross-shaft. Replace the fan, pulley, and belts.
  8.  
  9. Replace all the items removed from the engine earlier. Connect all the wires which were detached.
  10.  
  11. Replace the radiator and fan shroud, air cleaner, and battery or battery cables. Fill the cooling system and check the automatic transmission fuel level. Fill the crankcase with oil. Check for leaks.
  12.  

 
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