How to Replace the Water Pump on a 2002 GMC Envoy

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The water pump on the 2002 GMC Envoy is located directly above the crank shaft pulley and is driven by the serpentine belt. When replacing the pump, it is necessary to reuse the water pump pulley so the pulley must be removed from the pump b3efore you remove the pump. Removal of the water pump will require removing the electric fan shroud and a fan clutch wrench for the removal of the water pump pulley.

Things You'll Need

  • Socket and ratchet set
  • 1/4-inch ratchet
  • Drain pan
  • 1/4-inch drive torque wrench
  • 3/8-inch breaker bar
  • Box end wrench set
  • Line wrench set
  • Small pry bar
  • Fan clutch wrench
  • Soft wire brush
  • Torque wrench
  • 50-50 premixed Dex-Cool coolant
  • Suction gun

Removal

  • Lift the vehicle's hood and support it with the hood prop rod. Disconnect the negative battery cable with a box end wrench. Unscrew the cap from the radiator.

  • Place the drain pan under the passenger side corner of the radiator, just below the drain cock. Place the 1/4-inch ratchet into the fitting on the drain cock and rotate it counterclockwise until coolant begins to pour from the radiator drain spout, Allow the coolant to drain completely. Tighten the drain cock to 18 inch-pounds of torque with the 1/4-inch drive torque wrench. Remove the drain pan and dispose of the old coolant properly.

  • Draw a sketch of the accessory bolt routing with a pen and paper. Also note most models will have a sticker on the core support documenting belt routing, if using this sticker as a reference, verify it displays the correct routing on the engine.

  • Remove the plastic pins securing the radiator hood baffle to the core support and radiator. Remove the bolts securing the headlight housing panel and the grille to the core support. Remove the housing panel and grille assembly. Remove the two upper hood latch mounting bolts and the lower hood latch mounting bolt. Remove the hood latch support.

  • Disconnect the transmission cooler lines at the engine with a line wrench. Cap both ends of the transmission cooler lines. Remove the transmission cooler lines from the fan shroud. Remove the two upper bolts on the fan shroud with a socket and ratchet. Disconnect the upper radiator hose.

  • Install the fan clutch wrench onto the water pump pulley. Remove the hub nut for the fan with the socket and ratchet.

  • Remove the two bolts securing the fan shroud to the core support with the socket and ratchet. Use the pry bar to pop the wiring harness retainer from the fan shroud. Tilt the radiator and condenser toward the engine lightly and use the pry bar to unclip the shroud from the radiator at each side. Lift the fan shroud and fan from the engine.

  • Place the 3/8-inch breaker bar into the fitting on the belt tensioner. Rotate the breaker bar clockwise to relieve belt tension and slip the belt from around the tensioner. Slowly relieve pressure on the tensioner, allowing it to return to its normal resting position. Remove the serpentine belt from the engine.

  • Place the fan clutch wrench over two of the four water pump pulley bolts and break loose the other two with the socket and ratchet. Remove the fan clutch wrench and place it over the two bolts that have been broken loose and break loose the remaining two bolts. Remove all four water pump pulley bolts and remove the water pump pulley.

  • Remove the five bolts that secure the water pump to the engine with the socket and ratchet. Remove the water pump from the engine.

Installation

  • Clean the water pump mating surface at the engine with a soft wire brush. Place the new water pump gasket onto the new water pump and set the new water pump into the engine. Install the five mounting bolts and tighten each water pump bolt to 3 foot-pounds of torque and again at 8 foot-pounds of torque.

  • Place the water pump pulley onto the water pump. Install the pulley mounting bolts and tighten to 18 foot-pounds with the torque wrenc,h using the fan clutch wrench to hold the pump from rotating.

  • Inspect the serpentine belt for any cracks, glazing or other damage and replace if necessary. Route the serpentine belt around the crank pulley and engine accessories according to the belt routing diagram sticker or the sketch made previously, holding tension by hand at the belt tensioner. Install the 3/8-inch breaker bar into the belt tensioner and rotate the tensioner clockwise and slip the belt around the tensioner. Slowly release the breaker bar to apply tension to the belt.

  • Set the fan shroud in place on the radiator and apply pressure over the mounting clips to connect the shroud to the radiator. Pull the fan shroud to the core support and install the two mounting bolts; tighten to 21 foot-pounds with a torque wrench.

  • Install the fan and fan clutch onto the shaft at the water pump pulley. Install the fan hub nut and tighten to 41 foot-pounds with a torque wrench, using the fan clutch wrench to counter rotation of the water pump pulley.

  • Pour new 50-50 premixed Dex-Cool coolant into the radiator until the radiator is full. Start the engine and allow it to reach operating temperature. Inspect for any leaks. As the level of coolant drops in the radiator, add more coolant. Shut the engine off once it reaches operating temperature and replace any remaining coolant in the radiator until full. Install the radiator cap.

  • Use the suction gun to remove any old coolant from the coolant reservoir. Fill the coolant reservoir to the warm full line and close the cap.

  • Remove the caps for the transmission cooler lines. Connect the transmission cooler lines at the engine and tighten the fittings with a line wrench. Attach the transmission cooler lines to the fan shroud. Attach the electrical connector to the fan shroud.

  • Position the hood latch support onto the core support of the vehicle. Install all three mounting bolts and tighten them to 15 foot-pounds of torque. Install the head light housing panel and grill to the vehicle tighten all bolts with the socket and ratchet.

  • Place the radiator air baffle onto the radiator and core support. Install the push pin retainers to secure it to the vehicle.

  • Check the transmission fluid level and top it off with fresh Dexron VI transmission fluid, as needed.

Tips & Warnings

  • The 2002 GMC Envoy uses Dex-Cool coolant which cannot be mixed with other coolants. If you replace the drained coolant, use only Dex-Cool coolant.
  • Do not attempt any cooling system service until the engine is completely cool.

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References

  • Alldata: 2002 GMC Envoy Water Pump Replacement
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