GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1999 🢒 GMC P42 Commercial Chassis 🢒 Transmission/Transaxle 🢒 Automatic Transmission - 4L80-E 🢒 Oil Cooler Hose/Pipe Replacement

Removal Procedure

    Object Number: 178872 Size: SH
  1. Remove the quick connect fittings that secure the transmission oil cooler hoses to the auxiliary transmission oil cooler, if equipped.

    2. Object Number: 178867 Size: SH
  2. Remove the quick connect fittings that secure the transmission oil cooler hoses to the radiator.
  3. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.

    4. Object Number: 178883 Size: SH
  4. Remove the retaining clips that secure the transmission oil cooler hoses to the transmission oil cooler hose fittings.
  5. Discard the two retaining clips.

    6. Object Number: 178870 Size: SH
  6. Remove the transmission oil cooler hoses with the transmission oil cooler hose clips from the transmission oil cooler hose clip retaining brackets.

    7. Object Number: 178869 Size: SH
  7. Disconnect the auxiliary transmission oil cooler hose line nuts from the union, if equipped.
  8. Remove the transmission oil cooler hoses from the vehicle.
  9. Separate the transmission oil cooler hoses from the transmission oil cooler hose clips.

Installation Procedure

    Object Number: 178869 Size: SH
  1. Secure the transmission oil cooler hoses into the transmission oil cooler hose clips.
  2. Install the transmission oil cooler hoses to the vehicle.

    3. 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.

  3. Connect the auxiliary transmission oil cooler hose line nuts to the union, if equipped.

    4. Tighten
    Tighten the nuts to 14 N·m (124 lb in).


    Object Number: 178870 Size: SH
  4. Install the transmission oil cooler hoses with the transmission oil cooler hose clips to the transmission oil cooler hose clip retaining brackets.

    5. Object Number: 178883 Size: SH

    Important: Do not reuse the existing retaining clips that were removed from the transmission oil cooler hose fittings.

  5. Install the NEW retaining clips that secure the transmission oil cooler hoses to the transmission oil cooler hose fittings.
  6. Push the cooler lines into the transmission fittings until the cooler lines lock into place:
    7. 6.1. Lightly pull on the cooler hoses, away from the fitting, to ensure that the cooler hose is locked into the fitting.
    6.2. Position the plastic cap located on the cooler hose onto the hex fitting .
  7. Lower the vehicle.

    8. Object Number: 178867 Size: SH
  8. Install the quick connect fittings that secure the transmission oil cooler hoses to the radiator.

    9. Object Number: 178872 Size: SH
  9. Install the quick connect fittings that secure the auxiliary transmission oil cooler hoses to the auxiliary transmission oil cooler, if equipped.
  10. Check the transmission fluid level. Refer to Fluid Capacity Specifications .