This job is not particularly difficult. If you don't have a manual, you can often find one in the local library. An Internet search will also bring up instructions and photos of how to do this job. It basically involves first draining the cooling system, then removing the drive belts and any brackets attached to the water pump; removing all the pump mounting bolts (draw a diagram of where the bolts go, and which length goes where; if you have any doubt at all), and after confirming that the pump can now be moved (sometimes there is still a bolt holding the pump on, that has not been noticed), apply enough force to break the adhesive seal that holds the pump in place. The thing to remember is that it is vitally important to clean off ALL traces of old gasket material from the pump mounting surfaces on the engine. This is best done with a blade scraper; and followed up by running a finger over the entire area to see if you can feel any lumps or remaining bits of old gasket. The other essential point is to apply a thin, even coat of RTV silicone gasket sealer to both sides of the new gasket before putting it in place. I suggest using the gray color RTV formula; as it is more resistant to pressure. Then just install all the bolts in their respective holes, and tighten them evenly to the recommended tension. On my older 5.2 engine; it is recommended to coat the threads on one of
the long bolts with gasket sealer; as the hole for that bolt extends into
a water passage.
Install the accessory brackets and drive belts, and tighten the belts properly.
Changing the theromstat is a similar process; in that it is necessary
to clean off the mounting surface, and apply gasket sealer to the new
gasket. The thermostat must be installed with the spring end going into
the engine. If the thermostat flange or housing has a shallow circular
recess the same diameter as the thermostat machined into it; be sure
the thermostat is placed inside that recess before tightening down the
flange. If the thermostat is off center, and part of it extends outside
the recess; the flange will crack when you tighten the bolts down.
Be sure to clean the spigots where the hoses are attached, align the
hoses properly, and adequately tighten the hose clamps. Replace any
cracked or damaged hoses.
Fill the system at the radiator cap with a mixture of equal parts of coolant and distilled water; until it comes all the way to the top of the radiator. Then be sure the reservoir bottle is also filled to the proper level. Start the motor, run it until the temperature gauge is up to the normal level, and then shut it off and let it cool to the point where it is safe to remove the radiator cap. Recheck the coolant level at that time; it probably will be low, as there is inevitably trapped air that has to work its way out of the system. Keep rechecking the coolant level frequently until it stops going down.