There are a lot of steps, and you need to take your time. You will need access to a lift or jack stand, and make sure you keep the work area clean and organised, taking photos of the timing system will make your life easier when it comes to re-timing the engine.

Water Pump Replacement (2.4L)
Removal Procedure

1. Drain the coolant. Recover the coolant. Refer to Cooling System Draining and Filling.
2. Remove the exhaust manifold. Refer to Exhaust Manifold Replacement in Engine Exhaust.
3. Remove the coolant intake pipe. Refer to Engine Coolant Inlet Pipe Replacement in Engine Cooling.
4. Lower the vehicle.
5. Disconnect the heater hose quick connect from the heater outlet pipe.
6. Remove the timing chain and tensioner. Refer to Camshaft Timing Chain, Sprocket, and Tensioner Replacement in Engine Mechanical - 2.4L. (see below procedure)
7. Remove the water pump cover-to-cylinder block bolts.
8. Remove water pump pipe to cylinder block bolt.
9. Remove the 3?water pump-to-timing chain housing nuts.
10. Remove the water pump and cover assembly.
11. Remove the water pump cover-to-coolant pump assembly bolts.
12. Clean all sealing surfaces.

Important: Before you install the coolant pump, read the entire procedure. Follow the tightening sequences in order to avoid part damage and to provide proper sealing.


1. Install the pump cover bolts. Hand tighten the bolts.
2. Install water pump cover assembly.
3. Install the cover-to-block bolts. Hand tighten the bolts.
4. Install the coolant pump-to-timing chain housing nuts. Hand tighten the nuts.
Notice: Refer to Fastener Notice in Cautions and Notices.

5. Torque in sequence as follows:
   1. Tighten the water pump-to-timing chain housing nuts.
      Tighten
      Tighten water pump to timing chain housing nuts to 26?Y (19?lb?ft).
   2. Tighten the pump cover-to-pump assembly bolts.
      Tighten
      Tighten the water pump cove to water pump bolts to 14?Y (124?lb?in).
   3. Tighten the coolant pump cover-to-engine block bolts. Tighten the bottom bolt first.
      Tighten
      Tighten water pump to engine block bolts to 26?Y (19?lb?ft).
6. Install heater hose to pipe on water pump.
7. Install the exhaust manifold and install new gaskets. Refer to Exhaust Manifold Replacement in Engine Exhaust.
8. Install oil level indicator tube and indicator. Refer to Oil Level Indicator Tube Replacement in Engine Mechanical-2.4L.
9. Connect the brake vacuum pipe to the cam housing.
10. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
11. Install catalytic converter to to manifold. Refer to Catalytic Converter Replacement in Engine Exhaust.
12. Install the coolant inlet pipe. Refer to Engine Coolant Inlet Pipe Replacement.
13. Install the timing chain and tensioner. Refer to Camshaft Timing Chain, Sprocket, and Tensioner Replacement in Engine Mechanical - 2.4L.
14. Lower the vehicle.
15. Connect the oxygen sensor connector.
16. Fill cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
17. Inspect the system for leaks.

Caution: Refer to Battery Disconnect Caution in Cautions and Notices.
Notice: The timing chain on the LD9 (VIN T) Twin Cam Engine is not to be replaced with the timing chain from any other model year. The timing sprockets are different on the Twin Cam engine and the shape of the links matches the sprockets. Engine damage may result if the wrong timing chain is used. The timing chain and the crankshaft sprocket must be marked so that they are reinstalled in the same side facing out at the time of reassembly.

1. Disconnect the negative battery cable.
2. Remove the engine front cover. Refer to Engine Front Cover Replacement.
3. Rotate the crankshaft clockwise (as viewed from the front of the engine, normal rotation) until the camshaft sprocket timing dowel pin holes align with the holes in the timing chain housing.
4. Set the crankshaft sprocket keyway pointing upwards. Align with the centerline of the cylinder bores. This is the timed position.
5. Remove the timing chain guides.
6. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
7. Ensure that all of the slack in the timing chain is above the tensioner assembly.
8. Remove the timing chain tensioner bolts and the tensioner.
9. Remove the tensioner shoe. Use a small locking ring plier in order to engage the hole in the locking tab and remove the shoe from the stud.
Notice: Do not attempt to pry the sprocket off the camshaft or damage to the sprocket or chain housing could occur.
Important: Mark the timing chain and the crankshaft sprocket prior to removal. If the chain or the crankshaft sprocket is installed with the wear pattern in the opposite direction, noise and increased wear may occur.

10. Mark the crankshaft sprocket and the timing chain outer surface.
11. Remove the timing chain.
12. Lower the vehicle.
13. Holding the intake camshaft sprocket with J 39579, remove the sprocket bolt and washer.
14. Remove the washer from the bolt and rethread the bolt back into the camshaft.
15. Using a 3-jaw puller and the relief holes in the sprocket, remove the intake camshaft sprocket.
16. Repeat this procedure for the exhaust camshaft sprocket.
17. Clean the old sealant from the bolt with a wire brush.
18. Clean the threaded hole in the camshaft with a round nylon bristle brush.
19. Inspect the parts for wear. Replace the parts as necessary.Some scoring of the timing chain shoe and the guides is normal.
20. Replace the timing chain shoe or guides if the scoring exceeds 1.12?mm (45?in).

1. Use Adhesive/Sealant Compound GM?P/N?12345493 or equivalent on the camshaft sprocket bolt. Install the intake and exhaust camshaft sprockets onto the camshafts with the marked surface showing.Notice: Refer to Fastener Notice in Cautions and Notices.
   
2. Install the retaining bolts and washers to the intake and exhaust camshaft sprockets.
3. Tighten
   Tighten the bolts to 70?Y (52?lb?ft) while holding the sprockets with the J 39579.
4. Install the J 36800 through the holes in the camshaft sprockets into the holes in the timing chain housing. This will position the camshaft for correct timing.
5. If the camshafts are out of position (you must rotate the camshaft more than 1/8?turn in order to install the alignment dowel pins), use the following procedure:
   1. Rotate the crankshaft 90?degrees clockwise off of the TDC in order to give the valves adequate clearance to open.
   2. Once the camshafts are in position and the dowels installed, rotate the crankshaft counter clockwise back to the top dead center.

Notice: Do not rotate the crankshaft clockwise to TDC. Valve or piston damage could occur.
Important: The side of the timing chain that was marked during removal must be showing when the chain is installed.

6. Install the timing chain over the exhaust camshaft sprocket, around the coolant pump, and around the crankshaft sprocket.
   1. Remove the alignment dowel pin from the intake camshaft.
   2. Using the J 39579, rotate the intake camshaft sprocket counterclockwise enough in order to slide the timing chain over the intake camshaft sprocket.
   3. Release the J 39579. The length of the chain between the 2?camshaft sprockets will tighten.
   4. If properly timed the intake camshaft alignment dowel pin should slide in easily. If the dowel pin does not fully index, the camshafts are not timed correctly and the procedure must be repeated.
7. Leave the alignment dowel pins installed.
8. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
9. The timing marks on the crankshaft and on the cylinder block should be aligned when the slack is removed from the chain linking the intake camshaft sprocket and the crankshaft sprocket. If the marks are not aligned, move the chain one tooth forward or rearward, remove the slack and re-examine the marks.

Important: Use the following steps in order to reset the timing chain tensioner assembly to the zero position.

10. Reset the timing chain tensioner assembly.
    1. Insert the tensioner plunger assembly into the tensioner housing.
    2. With the tensioner plunger fully extended, turn the complete assembly upside down on a bench or other flat surface.
    3. With the plunger face against the workbench, press firmly on the bottom of the tensioner housing.
    4. Compress the plunger until the plunger is seated flush in the tensioner.


11. Check the plunger to make sure the plunger is out of the cylinder at the correct dimension. The correct dimension for the plunger to extend out of the cylinder is 1.7?mm (0.07?in) maximum.


12. Loosely install the tensioner assembly and bolts to the timing chain housing.
13. Install the timing chain tensioner shoe on the stud.
14. Apply hand pressure to the timing chain tensioner shoe until the locking tab seats in the groove in the stud.
15. Tighten the timing chain tensioner bolts. Do Not overtighten.
    Tighten
    Tighten the bolts to 10?Y (89?lb?in).


Important: If the timing chain tensioner is not released from the installation position, engine damage will occur when the engine is started.

16. Release the timing chain tensioner plunger.
    1. Using a flat blade screwdriver, cotter pin remover, or similar tool, press firmly against the face of the timing chain tensioner plunger.
    Important: If the timing chain tensioner cannot be depressed, the plunger is not properly reset and the procedure for resetting the timing chain tensioner should be repeated.
    
    2. Depress the timing chain tensioner plunger until the plunger is bottomed out in the bore of the timing chain tensioner.
    3. Release the tensioner plunger. the plunger should press firmly against the back of the timing chain tensioner shoe.
17. Remove J 36800 from the camshaft sprockets.
18. Rotate the crankshaft clockwise 2?full rotations. Align the crankshaft keyway with the mark on the cylinder block, and reinstall the alignment dowel pins. The pins should slide in easily if the engine is timed correctly.


19. Install the timing chain guides.
20. Install the engine front cover. Refer to Engine Front Cover Replacement.
21. Connect the negative battery cable.
    Tighten
    Tighten the bolt to 16?Y (12?lb?ft).