Try either lubrication or heat
The thermostat is on the top-right of the engine toward the front. The upper raditor hose connects to it. MAKE SURE the engine is cold before attempting to remove the thermostat. There are 2 bolts which secure the thermostat housing. Remove the bolts, remove the thermostat housing and the thermostat sits right underneath. Reach in and remove it. There some good pictures at this link to help locate the thermostat housing..http://www.autoclinix.com/Manifold2.htm
Allow the engine to warm up fully before unscrewing those bolts. If they break off in the brass inserts of the plastic intake, replace the intake.
remove the belt remove the 3-4 bolts on the steering pump remove the 3-4 bolts on the thermostat reinstall the same
Drain the radiator. Remove the upper radiator hose at the engine. Remove the bolts holding the thermostat housing. Remove the housing and the thermostat. Clean both surfaces and install the thermostat and gasket. Install the housing,bolts,the hose and refill the radiator.
Drain the radiator into a container. Remove the upper radiator hose at the engine. Remove the2 bolts on the thermostat housing and lift it up. Remove the thermostat and clean the surfaces. Install the thermostat and the bolts. install the top radiator hoes and fill the radiator.jd
Remove the water supply hose from your 1987 Chevy Astro thermostat housing. Remove the thermostat housing retaining bolts. Remove the old thermostat and drive in the new thermostat.
Drain the water from the cooling system. Remove the water supply line to the thermostat. Remove the thermostat housing bolts. Remove the thermostat. Reverse the process to install the new thermostat.
Remove the water supply hose from the thermostat housing. Remove the thermostat housing retaining bolts. The thermostat will lift out. Reverse the process to install the new thermostat.
Drain the radiator into a container. Remove the upper radiator hose at the engine and remove the 2 thermostat housing bolts. Remove the thermostat and clean the surfaces. Install the new thermostat,housing and bolts. Reinstall the upper hose and top off the system.
Drain the radiator into a container. Remove the top radiator hose at the engine. Remove the 2 bolts holding the thermostat housing. Remove the thermostat and clean the surfaces. Install the new thermostat, housing,and bolts. Reinstall the top radiator hose and fill with coolant.
Drain the water from the cooling system. Remove the water hose from the thermostat housing. Remove the thermostat housing retaining bolts. Remove the thermostat. Reverse the process to install the new thermostat.
There are a few guidelines that will help you to change a thermostat in a 2000 Silverdo. Remove the clamp and detach the hose on the thermostat and then remove the bolts that hold the thermostat to the manifold and replace it with the new one and screw back the bolts and the clamp.?æ