Where is the thermostat located on a 1998 Chevy Lumina?
At the engine end of the upper rad hose. Make sure when replacing it the spring goes toward the engine.
What is causing the antifreeze to leaking your 1998 Chevy lumina when there are not any spots on the ground?
Follow the upper radiator hose down to the engine. It is attached to the thermostat housing . There will be two bolts attaching the housing to the engine. Remove these bolts, and with a little effort (prying), the housing will come off. There will probably be brackets, wires, or other items which will have to be removed in order to get to the bolts. Installation is just the reverse, and be careful you don't get…