How to Change the Thermostat in a Chevy Silveradoby Contributor; Updated November 07, 2017
Items you will need
Wrench or socket
Thermostat and gasket
New coolant (if necessary)
How to Change the Thermostat in a Chevy Silverado. If you notice your Chevy Silverado running hot or the heater not blowing warm air, you'll likely need to change the thermostat. The procedure is the same whether you're driving the light duty 1500 model, or if you own the heavy duty 2500- or 3500 Silverado.
Open the draincock at the bottom of the radiator and drain the coolant from your Silverado. Use a clean container and reuse the coolant if it's relatively new.
Follow the upper radiator hose to the thermostat housing at the top of the intake manifold. Loosen the hose clamp with a screwdriver and pull off the end of the radiator hose from the thermostat housing. Remove the two bolts on either end of the thermostat housing cover and pull off the cover.
Take out the old thermostat. Scrape off the old thermostat gasket residue from the inside of the thermostat housing cover. Stuff an old rag into the thermostat housing to prevent debris from getting inside the housing.
Insert the new thermostat into the thermostat housing with the spring-side of the thermostat facing into the engine. Install the new thermostat gasket. Replace the thermostat housing cover and tighten the two bolts.
Reattach the upper radiator hose to the thermostat housing. Refill the radiator with reserve or new coolant. Start your Chevy Silverado and run with the radiator cap off to allow any air to escape from the radiator. After a few minutes, install the radiator cap.
Allow the engine of your Silverado to warm up. Touch the upper radiator hose to verify it is getting hot, indicating the thermostat is working. Check for leaks where the radiator hose attaches to the thermostat housing and tighten the hose clamp to stop any leaks, if necessary.
Note that a Chevy Silverado with a 6.6L diesel engine has two thermostats inside a larger thermostat housing. Remove four bolts to take off the housing cover. Install the rear thermostat with the two vent valves facing the rear of the engine. Follow the radiator hose to the water pump housing if your Chevy Silverado has a 4.8, 5.3 or 6.0L engine.
Don't drain coolant from your Chevy Silverado while the engine is hot.