GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

Thermostat

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CAUTION
Never open, service, or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. In addition, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

REMOVAL & INSTALLATION



3.0L Engine
  1. Drain and recycle the engine coolant.
  2.  
  3. Remove the air intake plenum.
  4.  
  5. Remove the intake manifold.
    1. Remove the bolts.
    2.  
    3. Lift and support the manifold to allow access to the thermostat.
    4.  
    5. Remove the intake manifold seals.
    6.  

  6.  
  7. Remove the radiator inlet hose from the thermostat outlet pipe.
  8.  
  9. Remove the outlet pipe bolt, and the thermostat outlet pipe.
    1. Remove the O-ring seals.
    2.  

  10.  
  11. Unbolt the thermostat housing bolts. Remove the thermostat housing with the thermostat.
    1. Tilt the rear of the thermostat housing upward, then lift it out.
    2.  
    3. Remove the seal ring.
    4.  

  12.  



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Fig. Location of the Thermostat outlet pipe-3.0L Engine



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Fig. The thermostat housing (2) is mounted to the engine using two retaining bolts (1) on the 3.0L Engine

To install:

  1. Install the thermostat housing with the thermostat and new seal ring.
  2.  
  3. Install the housing bolts and tighten to 15 ft. lbs. (20 Nm).
  4.  
  5. Install new O-ring seals and lubricate with coolant.
  6.  
  7. Install the thermostat outlet pipe bolt and tighten to 15 ft. lbs. (20 Nm).
  8.  
  9. Connect the Radiator inlet hose to the thermostat outlet pipe.
  10.  
  11. Install the intake manifold.
    1. Install new seals.
    2.  
    3. Position the intake manifold.
    4.  
    5. Install new intake manifold bolts. Tighten the new bolts to 15 ft. lbs. (20 Nm).
    6.  

  12.  
  13. Install the air intake plenum.
  14.  
  15. Refill the engine cooling system.
  16.  

4.5L and 4.9L Engines
  1. Drain the coolant to a level below the thermostat housing.
  2.  
  3. It may be necessary to remove the upper air filter assembly on some models.
  4.  
  5. Remove the 2 bolts securing the upper thermostat housing to the lower housing.
  6.  
  7. Remove the upper thermostat housing.
  8.  
  9. Remove the thermostat and O-ring from the lower housing.
  10.  



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Fig. Thermostat installation-4.5L and 4.9L engines

To install:

  1. Install the thermostat and a new O-ring to the lower housing.
  2.  
  3. Install the upper thermostat housing to the lower housing. Tighten the thermostat housing bolts to 20 ft. lbs. (27 Nm).
  4.  
  5. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
  6.  
  7. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.
  8.  

4.6L Engine
  1. Drain the coolant to a level below the thermostat housing.
  2.  
  3. On some vehicles, access is easier if the front-end beauty panel and the air cleaner are removed.
  4.  
  5. Remove the 2 bolts securing the thermostat housing to the intake manifold.
  6.  
  7. Remove the thermostat housing.
  8.  
  9. Remove the thermostat and O-ring from the housing.
  10.  



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Fig. Thermostat installation-4.6L Engine



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Fig. Loosen the upper radiator hose clamp at the thermostat housing



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Fig. Remove the upper radiator hose clamp from the thermostat housing



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Fig. Remove the thermostat housing retaining bolts and . . .



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Fig. . . . remove the thermostat housing from the engine



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Fig. Separate the thermostat from the housing

To install:

  1. Install the thermostat and new O-ring to the housing.
  2.  
  3. Install the thermostat housing to the intake manifold. Tighten the thermostat housing bolts to 18 ft. lbs. (25 Nm).
  4.  
  5. Refill the cooling system using a 50/50 mixture of water and ethylene glycol antifreeze.
  6.  
  7. Install the air cleaner and beauty panel, if removed.
  8.  
  9. Start the engine and check for coolant leaks. Allow the engine to come to normal operating temperature. Recheck for coolant leaks.
  10.  

 
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