GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1998 🢒 Chevy P12 Chassis 🢒 Engine 🢒 Engine Cooling 🢒 Engine Coolant Thermostat Replacement

Removal Procedure

    Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  1. Disconnect the negative battery cable.
  2. Drain the cooling system until the radiator coolant level is below the thermostat.
  3. Relieve the upper radiator hose spring clamp tension and remove the hose from the thermostat housing.

    4. Object Number: 72728 Size: SH
  4. Remove the thermostat housing studs.
  5. Remove the thermostat housing.
  6. Remove the thermostat.
  7. Inspect the thermostat housing. Inspect the coolant outlet sealing surfaces. Clean the mating surfaces of any corrosion and remaining gasket material.

Installation Procedure

    Object Number: 72728 Size: SH
  1. Install the thermostat into the coolant outlet.
  2. Place the new gasket into position.
  3. Install the thermostat housing.

    4. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  4. Install the retaining studs.

    5. Tighten
    Tighten the studs to 37 N·m (27 lb ft).

  5. Install the upper radiator hose to the thermostat housing and tension the spring clamp.
  6. Fill the cooling system. Refer to Cooling System Draining and Filling .

    7. Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components.

  7. Connect the negative battery cable.