Chevrolet Repair: thermastat, flat head screwdriver, drip pan

Question
how to replace the thermostat in a 1997 astro van

Answer
Tools Needed: Flat head screwdriver or nut drivers, ratchet and socket, drip pan, a rag, flat scraper to remove the old gasket.
Time needed: 20-40 minutes

Although water pump failure is often the cause of overheating, it never hurts to take a quick look at what could prove to be a simple quick fix. As often as the water pump goes bad, so does that pesky thermostat.

Because the thermostat is cheap and replacing it is simple it isn't a bad idea to try this repair before getting into more difficult manuevers.

Here I am only going to briefly describe the procedure to change your thermostat. For more details, including how to test your thermostat and water pump visit the engine repair section of the Jonko Forum.

Locate and Remove the Thermostat
Although some thermostats are located where the bottom radiator hose joins the engine, the vast majority are on the top hose. Locate the hose and unscrew the clamp that attaches it to the engine.

When the clamp is loose, pull the hose from the engine. You may lose a bit of fluid here so make sure you have a drip pan in place under the vehicle.

When the hose is removed you will need to remove the bolts that hold the thermostat housing in place. Once you have removed the housing, simply lift out the old thermostat.

Clean up and install the new thermostat
In all likelyhood, some of the gasket that rested between the housing and the engine will remain stuck. Remove the old gasket by plugging the hole with a rag and scraping away the gasket. This will insure that none of the old gasket accidentally falls into the cooling system.

After you have cleaned up the area, you are ready to install your new thermostat. You should always use the recommended unit because thermostats that open at the wrong temperature can cause several problems resulting in sludged oil and damaged components.

Set the gasket in place and remember to install the thermostat with the power unit pointed towards the engine block. After it is in place, replace the bolts and snug it down.

Finish the job
After you have tightened it down, replace the hose and clamp you removed earlier. If you lost any fluid during the job, you will want to refill the system.  I recommend filling with fresh fluid

After you have filled your system, you are ready to go.