2003 Silverado Water Pump Replacement - 5.3 Liter

OchAyeZ71 · February 7, 2011

This is what I did on my 2003 Silverado with 5.3 liter motor at 94k mi. In my case the left gasket was leaking (gasket leaks seem to be the common issue). The right gasket was ok I also replaced the thermostat since it is attached to the water pump and is easy to replace with the pump off. I have seen some good posts on this so I thought I would add my experience with it. It is pretty easy overall, and could be done in less than three hours depending on how long you spend on cleaning the gasket surfaces on the motor.

Parts used

- New water pump ($130 from Napa )

- comes with alluminum gaskets, thermostat oring/gasket and screws for the thermostat

- New thermostat ($26 from Napa)

- Dexcool Antifreeze ($12/gal from Walmart, will need two)

- Distilled water (cheap)

Tools used - mostly Crafsman

- Couple of buckets for the anti freeze

- Fan removal tool - 36mm flavor (borrowed from Autozone)

- 15mm, 10mm, 8mm sockets

- flat head screw drivers

- channel lock/pliers

- 3/8 air ratchet (air tools are fun)

- standard 3/8 and 1/4 in ratchet

- 3/8 torque wrench

Removal

1. Start draining radiator from drain plug

2. Remove plasic engine cover (says Vortec on it) then the Intake hose (will need to open the plastic hose clamp attached to the upper radiator hose for removal)

3. Remove upper radiator hose from water pump (move hose out of the way....does not need to disconnected from the radiator)

4. Remove upper radiator shroud (two 10mm screws, 4 plastic clips)

5. Remove fan (used 36mm fan removal). Mine broke loose with three taps of a hammer. (removes CCW)

6. Remove lower radiator shroud. This is not really necessary but there is nothing really holding it in once the upper is removed

7. Remove primary and AC belt. AC belt is not necessay, but I did not want to get it covered with anti freeze. Both are easy to remove.

8. Cover AC compressor with plastic bag. I did this to prevent it from getting covered with anti freeze when the lower hose and heater hoses were removed

9. Remove lower radiator hose from water pump and two heater hoses. Be prepared for "niagra falls" here. By now you should be able to tighten the radiator drain plug.

10. Remove belt tensioner from water pump.

11. Remove idler pully next to alternator. This makes it easier to access the bolts and gasket surface on the right side of the water pump and is very easy to remove.

12. Remove 6 10mm bolts holding the water pump in and lift out the pump. I was about 45min into it at this point.

13. Clean the gasket surface areas. I used a razor blade and 320/600 grit wet sand paper. There is probably a better way to do this as it was a bit time consuming.

The Napa water pump came with alluminum gaskets with red silicon material molded into the gasket for the seal. I used them without any additional RTV. The felpro gaskets have blue material. Other than that they look the same.

Installation - There are probably several ways to do this, I thought it would be best to alternate tightening the screws for the pump

14. Place two of the three screws on both sides through the new water pump with the gaskets in place then hold the pump in front of the motor where it mounts.

15. Start the two screws on each side, then start the third screw on each side. Make sure the gaskets do not fall off or slip.

16. Install all screws to a pre snug state.

17. Alternate left to right tightening the screws until snug, then alternate tightening until all were torqued to 22ftlbs (I have read several posts stating this is the appropriate torque)

18. Installed the new thermostat using the new scews that came with the pump. I used some loctite on the screws. The new thermostat already had the oring installed.

19. The rest is just the reverse of the removal; tensioner, idler pully, belts, fan, hoses, intake.

20. I filled it up with 50/50 mix of dexcool and distilled water at the overflow. Mine took in about 2.5 gallons.

21. Started it up and let it warm up until the thermostat opened at ~190 degrees. Have an extra mix ready since it will take in some coolant once it starts up, at least mine did. I left the cap off until it warms up.

I did this yesterday and all seems to be ok after some road testing.