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

Engine

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REMOVAL & INSTALLATION



See Figures 1, 2, 3, 4, 5, 6, 7, 8 and 9

Buick Built V6
  1. Scribe marks around the hood hinges and hinge bracket, so the hood can be installed easily. Remove the hood.
  2.  
  3. Disconnect both battery cables.
  4.  
  5. Drain the coolant into a suitable container; it can be reused if in fresh condition.
  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 air cleaner.
  2.  
  3. Disconnect the radiator and heater hoses and position them out of the way.
  4.  
  5. On air conditioned vehicles, disconnect the A/C compressor ground wire from the mounting bracket. Remove the electrical connector from the compressor clutch, remove the compressor-to-mounting bracket attaching bolts and position the compressor out of the way. DO NOT disconnect the refrigerant hoses.
  6.  


CAUTION
If the compressor refrigerant lines do not have enough slack to position the compressor out of the way without discharging the refrigerant lines, the air conditioning system will have to be discharged by a trained air conditioning specialist with a recovery/recycling station. Under no circumstances should an untrained person attempt to disconnect the air conditioning refrigerant lines. These lines contain pressurized R-12 refrigerant, which can be extremely dangerous.

  1. Remove the fan blade, pulleys and belts.
  2.  
  3. Remove the fan shroud assembly.
  4.  
  5. Remove the power steering pump-to-mounting bracket bolts and position the pump out of the way.
  6.  
  7. Tag, remove and plug the fuel pump hoses.
  8.  
  9. Tag and disconnect the vacuum lines from the engine to parts not attached to the engine. Disconnect the engine wiring harness.
  10.  
  11. Disconnect and tag the throttle cable, downshift cable and/or throttle valve cable at the carburetor.
  12.  
  13. Disconnect the transmission oil cooler lines at the transmission. Disconnect the oil and coolant sending unit switch connections at the engine.
  14.  
  15. Disconnect the engine-to-body ground strap at the engine.
  16.  
  17. Raise and support the front end of the vehicle with jackstands. Disconnect the starter cables and the cable shield from the engine.
  18.  
  19. Disconnect the exhaust pipes from the exhaust manifolds and support the exhaust system.
  20.  
  21. Remove the flywheel cover pan. Remove the flywheel-to-torque converter bolts. Using a scribe or felt tip marker, matchmark the flywheel-to-torque converter relationship for later assembly.
  22.  
  23. Remove the transmission-to-engine attaching bolts from the transmission bell housing.
  24.  
  25. Remove the cruise control bracket, if so equipped.
  26.  
  27. Remove the motor mount bolts.
  28.  
  29. Lower the vehicle and support the transmission with a floor jack.
  30.  
  31. Check to make sure that all wiring and hoses have been disconnected. Attach a lifting device to the engine and raise the engine just enough so that the engine mount through-bolts can be removed.
  32.  
  33. Raise the engine and transmission alternately until the engine can be disengaged and removed.
  34.  

To install:
  1. It may be necessary to alternately raise and lower the transmission to fit the motor mount through-bolts into position. Torque the through-bolt nuts to 35 ft. lbs. (48 Nm). Torque the automatic transmission-to-engine bolts to 35 ft. lbs. (48 Nm).
  2.  
  3. Raise the vehicle and support the transmission with a floor jack.
  4.  
  5. Install the motor mount bolts and torque to 55 ft. lbs. (75 Nm).
  6.  
  7. Install the cruise control bracket, if so equipped.
  8.  
  9. Install the transmission-to-engine attaching bolts to the transmission bell housing.
  10.  
  11. Install the flywheel cover pan. Install the flywheel-to-torque converter bolts at the matchmark of the flywheel-to-torque converter relationship.
  12.  
  13. Connect the exhaust pipes to the exhaust manifolds.
  14.  
  15. Lower the front end of the vehicle. Connect the starter cables and the cable shield to the engine.
  16.  
  17. Connect the engine-to-body ground strap at the engine.
  18.  
  19. Connect the transmission oil cooler lines at the transmission. Connect the oil and coolant sending unit switch connections at the engine.
  20.  
  21. Connect the throttle cable, downshift cable and/or throttle valve cable at the carburetor.
  22.  
  23. Connect the vacuum lines attached to the engine. Connect the engine wiring harness.
  24.  
  25. Connect the fuel pump hoses.
  26.  
  27. Install the power steering pump-to-mounting bracket bolts.
  28.  
  29. Install the fan shroud assembly.
  30.  
  31. Install the fan blade, pulleys and belts.
  32.  
  33. On air conditioned vehicles, connect the A/C compressor ground wire to the mounting bracket. Install the electrical connector to the compressor clutch, install the compressor and bracket attaching bolts.
  34.  
  35. Connect the radiator and heater hoses.
  36.  
  37. Install the air cleaner.
  38.  
  39. Refill the coolant into the radiator and reservoir. DON'T FORGET to refill the engine with the specified engine oil.
  40.  
  41. Connect both battery cables.
  42.  
  43. Install the hood around the marks on the hood hinges and hinge bracket.
  44.  
  45. Start the engine and check for vacuum, coolant, oil, fuel and refrigerant leaks. Adjust timing and idle speed to specification.
  46.  



Click image to see an enlarged view

Fig. Fig. 1: Exploded view of a common engine mount assembly

V8 Including Diesel
  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. Scribe the hinge outline on the underside of the hood. Remove the hood attaching bolts and remove the hood.
  2.  
  3. Disconnect the battery cables.
  4.  
  5. Remove the radiator and heater hoses and remove the air cleaner.
  6.  
  7. Remove the V-belts to avoid damaging them as the engine is pulled out of the engine compartment.
  8.  
  9. Disconnect the transmission oil cooler lines. Remove the fan shroud, fan belts, and pulleys. On diesels, disconnect the engine oil cooler lines at the radiator. Remove the upper radiator support and remove the radiator.
  10.  
  11. Disconnect the battery ground cable from the engine. Remove the radiator.
  12.  
  13. Disconnect the exhaust pipe or pipes or crossover at the exhaust manifolds.
  14.  
  15. Disconnect the vacuum line to the power brake unit.
  16.  
  17. Disconnect the accelerator to carburetor linkage. On diesels, disconnect the hairpin clip at the bellcrank.
  18.  
  19. Disconnect and label all the engine component wiring that would interfere with the engine removal, such as alternator wires, gauge sending unit wires, primary ignition wires, engine-to-body ground strap, etc.
  20.  
  21. Disconnect and plug the fuel line at the fuel pump. On diesels, also disconnect fuel pump wiring.
  22.  
  23. Detach the power steering pump and position to the left. Do not disconnect the hoses.
  24.  
  25. Detach the air conditioner compressor at the bracket and position to the right. DO NOT disconnect the hoses.
  26.  


CAUTION
If the compressor refrigerant lines do not have enough slack to position the compressor out of the way without disconnecting the refrigerant lines, the air conditioning system will have to be discharged by a trained air conditioning specialist with a recovery/recycling station. Under no conditions should an untrained person attempt to disconnect the air conditioning refrigerant lines. These lines contain pressurized R-12 gas which can be extremely dangerous.

  1. Disconnect the starter cable and remove the cable shield.
  2.  
  3. Disconnect the AIR pipe-to-catalytic converter, if there is one.
  4.  
  5. Remove the flywheel cover pan. Remove the flywheel-to-torque converter bolts. Matchmark the flywheel and torque converter for reassembly.
  6.  
  7. Separate the engine from the transmission at the bell housing. On 1987 models, remove 5 of the bolts and leave the lower/left bolt in place.
  8.  
  9. Remove the cruise control bracket, if so equipped.
  10.  
  11. Support the transmission with a floor jack.
  12.  
  13. Attach a lifting device to the engine and raise the engine slightly so the engine mount through-bolts can be removed.
  14.  
  15. Check to make sure all of the wiring and hoses have been disconnected. Raise the engine enough to clear the motor mounts.
  16.  
  17. Raise the engine and transmission alternately until the engine can be disengaged and removed. Once both are raised slightly, remove the remaining transmission-to-engine bolt on the 1987 models.
  18.  
  19. Install by reversing the procedure. When installing an engine, the front mounting pad to frame bolts should be the last mounting bolts to be tightened. Note that there are dowel pins in the block that have matching holes in the bellhousing. These pins must be in almost perfect alignment before the engine will go together with the transmission. Torque the through-bolt nuts to 35 ft. lbs. (48 Nm). Torque the automatic transmission-to-engine bolts to 35 ft. lbs. (48 Nm). When tightening the three converter-to-drive plate bolts, first tighten all three finger tight, and then torque to 46 ft. lbs. (63 Nm), all three. Make sure to retighten and torque the first bolt tightened.
  20.  

To install:
  1. When installing an engine, the front mounting pad to frame bolts should be the last mounting bolts to be tightened.
  2.  

There are dowel pins in the block that have matching holes in the bellhousing. These pins must be in almost perfect alignment before the engine will go together with the transmission.

  1. Torque the through-bolt nuts to 35 ft.lbs. (48 Nm). Torque the automatic transmission-to-engine bolts to 35 ft.lbs. (48 Nm). When tightening the three converter-to-drive plate bolts, first tighten all three finger tight, and then torque (46 ft.lbs. 63 Nm), all three. Make sure to retighten and torque the first bolt tightened.
  2.  
  3. Lower the engine and transmission alternately until the engine can be engaged. Once both are lowered slightly, install the remaining transmission-to-engine bolts.
  4.  
  5. Check to make sure all of the wiring and hoses have not gotten pinched between the engine and transmission. Lower the engine enough to engage the motor mounts.
  6.  
  7. Using the lifting device, raise the engine slightly so the engine mount through-bolts can be installed.
  8.  
  9. Support the transmission with a floor jack.
  10.  
  11. Install the cruise control bracket, if so equipped.
  12.  
  13. Install and tighten the flywheel-to-torque converter bolts to 50 ft. lbs. (68 Nm). Install the flywheel cover. Matchmark the flywheel and torque converter.
  14.  
  15. Connect the AIR pipe-to-catalytic converter, if there is one.
  16.  
  17. Connect the starter cable and install the cable shield.
  18.  
  19. Reposition the air conditioner compressor to the bracket.
  20.  
  21. Connect the power steering pump. Do not disconnect the hoses.
  22.  
  23. Connect the fuel line at the fuel pump. On diesels, also connect the fuel pump wiring.
  24.  
  25. Connect all the engine component wiring that would interfere with the engine installation, such as alternator wires, gauge sending unit wires, primary ignition wires, engine-to-body ground strap, etc.
  26.  
  27. Connect the accelerator to carburetor linkage. On diesels, connect the hairpin clip at the bellcrank.
  28.  
  29. Connect the vacuum line to the power brake unit.
  30.  
  31. Connect the exhaust pipe or pipes or crossover at the exhaust manifolds.
  32.  
  33. Connect the battery ground cable to the engine. Install the radiator.
  34.  
  35. Connect the transmission oil cooler lines. Install the fan shroud, fan belts, and pulleys. On diesels, connect the engine oil cooler lines at the radiator. Install the upper radiator support.
  36.  
  37. Install the V-belts.
  38.  
  39. Install the radiator, heater hoses and install the air cleaner.
  40.  
  41. Connect the battery cables.
  42.  
  43. Install the hood and attaching bolts at the scribes on the hinge outline on the underside of the hood.
  44.  
  45. Refill the engine cooling system. DON'T FORGET to refill the engine with the specified engine oil.
  46.  
  47. Start the engine and check for vacuum, coolant, oil, fuel and refrigerant leaks. Adjust timing and idle speed to specification.
  48.  



Click image to see an enlarged view

Fig. Fig. 2: Oldsmobile 307 (Y) engine mount assembly



Click image to see an enlarged view

Fig. Fig. 3: Mark the hood around the hinges to make installation easier later



Click image to see an enlarged view

Fig. Fig. 4: Removing the hood attaching bolts



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Fig. Fig. 5: Some models may utilize a small attaching bolt on the side. Be sure an assistant holds the hood during removal



Click image to see an enlarged view

Fig. Fig. 6: Labeling hoses and wiring before disconnection will make installation much easier



Click image to see an enlarged view

Fig. Fig. 7: Removing the motor mount attaching bolts



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Fig. Fig. 8: Removing the motor mount from the vehicle



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Fig. Fig. 9: Inspect the motor mounts for cracks and other types of damage

 
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