How do you change the thermostat & refill the coolant on a 2005 chevy silverado? 5.3 liter engine.

Changing a thermostat is not too different from car to car. Your looking for something like the image in the photo below.
Try this when the engine is COLD.
-Drain the coolant out of the system.
-Remove the two bolts holding the housing in place. Located on side of the engine, near the front.
-Lift the housing off.
-Remove the thermostat. Note which way up it is.
-Position the new one the same way up as the old one.
-Make sure the rubber O rings are seated correctly.
-Re-position the housing over the new part.
-Screw the two bolts back into position.
-Tighten to the correct torque. "Tightened but not forced"
-Refill the system with the correct coolant.
-Run the engine at idle until it gets up to working temperature and let continue to idle for a few more minutes.
-Turn off the engine and let in cool down for at least an hour.
-Return to the car and check the coolant level. Top up if you need to.
-Over the next two or three days of use check the level to make sure it hasn't changed.

All I have done for 49 years is drain the radiator & then
refill with 50/50 or 60/40

If you do every 3 years your okey

People are obsessed with coolant & trans flushing,why?

You do not have the engine running until you have it refilled
then add as the thermostat opens & fill the degas bottle

For how to change coolant on chevy pickup,click the link below and follow the detailed procedure:---
http://answerguide.blogspot.com/2012/01/how-to-change-coolant-on-chevy-2500.html
---------Thanks.

1 Remove the air intake duct hose from Mass Air Flow sensor.
( Air filter end)
2 Disconnect PCV hose
3 Remove air Intake adapter assy. From Throttle body
4 Drain Coolant.
5 Remove 2 bolt / studs from thermostat housing
6 Remove thermostat housing.
7 Remove thermostat. clean gasket and sealing surfaces
8 install new thermostat with new gasket/ seal
9 install thermostat housing torque bolt/Studs to 18 ft. lbs.
10 Reassemble the rest in reverse order
11 Fill coolant to proper level, check coolant level after running engine.
Top off *** necessary when engine is cool.

1. 1 Drain the coolant from your Explorer into an adequate container by opening the drain plug at the bottom of the radiator. Save the coolant for reuse if it is relatively new and clean.
   
2. 2 Remove the negative battery cable from the battery if your Explorer has a 2.9-, 3.0-, 4.0- or 5.0-liter engine. This step is not necessary for 2.3- and 2.5-liter engines.
   
3. 3 Follow the upper radiator hose to the front driver's side of the intake manifold, where it meets the engine. This is where the thermostat housing on your Ford Explorer is located. If necessary, remove the air cleaner duct for easy access to the housing.
   
4. 4 Loosen the clip on the end of the radiator hose and pull the hose off the thermostat housing. Use a 10mm wrench or socket to remove the two retaining bolts on the thermostat housing cover. Remove the cover.
   
5. 5 Note the position of the thermostat before removal. Pull out the old thermostat. Seat the new thermostat inside the housing in the same position as the old one, spring-side facing into the engine. Install new gasket over the thermostat.
   
6. 6 Reattach the thermostat housing cover and the radiator hose. Reinstall the air cleaner duct if removed earlier. Fill the radiator with reserve or new coolant. Start your Explorer and run with the heater blowing until the engine gets warm. Check for leaks.
   

Read more: How to Change the Thermostat in a Ford Explorer ' eHow.com http://www.ehow.com/how_4484916_change-thermostat-ford-explorer.html#ixzz1CLSvmPwR

I can almost guarantee the engine coolant temperature sensor is faulty or very dirty. You will find it on the top of the intake manifold, just beside the thermostat or upper rad hose housing. It is a 2 wire sensor, brass. It can be removed with a 3/4" or 19mm deep socket. It is the primary input to the engine computer before the O2 sensors take control (after engine warms up). Don't attempt to remove when hot or under pressure, refill and bleed after. You will notice a huge difference to fuel economy.

Yes, you probably have air in the system. Park uphill and run the engine with the heater on to get air out. Refill radiator. If air comes back or continues to bubble up in radiator, you may have a leaky head gasket.

Drain coolant first,remove the thermostat housing bolts,clean gasket surfaces,install the new thermostat and gasket.Tighten the thermostat housing boltsto 21 ft.lbs.(28Nm).Refill with coolant start the engine and check for leaks.

once truck is warm check both heater core hoses to make sure they are both warm if not then check the cold water valve could be stuck shut not allowing coolant to travel in to heater core.

try checking the hoses for blockage,and if not that make sure the fan is working right as it might be the fan cluch,or your water pump may have went out,best of luck