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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 352 (ENGINE COOLING SYSTEM)REMOVAL AND INSTALLATIONTHERMOSTAT REPLACEMENT - L61REMOVAL
1999 GMC Forward Control 5.7 R, Automatic

Thermostat Replacement - L61: Removal

1999 GMC Forward Control 5.7 R, AutomaticSECTION Removal
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: The thermostat will not function correctly once come in contact with oil. If oil is found in the cooling system, it must be flushed and the thermostat cartridge replaced.
  1. Drain coolant.
    Fig 1: Draining Coolant
    G01041181Courtesy of GENERAL MOTORS CORP.
  2. Remove exhaust heat shield bolts.
  3. Remove exhaust heat shield.
  4. Raise vehicle.
    Fig 2: Removing Exhaust Heat Shield
    G01041182Courtesy of GENERAL MOTORS CORP.

    IMPORTANT:  A drain plug has been provided at the bottom of the water pump assembly for additional coolant drainage from engine block and water pump.

  5. Drain coolant from water pump drain plug.
    Fig 3: Draining Coolant From Water Pump Drain Plug
    G01041183Courtesy of GENERAL MOTORS CORP.
  6. Remove thermostat cover bolts from thermostat housing.
  7. Remove and discard thermostat housing O-seal.
    Fig 4: Removing Thermostat Cover Bolts From Thermostat Housing
    G01041184Courtesy of GENERAL MOTORS CORP.

    IMPORTANT:  Twist water feed pipe while pulling to remove it from the water pump.

  8. Remove water pipe from water pump assembly.
  9. Remove and discard seals from water pipe.
  10. Remove inner thermostat sleeve.
  11. Remove thermostat assembly.
    Fig 5: Removing Thermostat Assembly
    G01041185Courtesy of GENERAL MOTORS CORP.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.