1993 Pontiac Sunbird Owner's Manual - Page 136

6. Put the cap back on coolant the 7. Start the engine and let it rununtil 9. Replace the thermostat, making sure recovery tank, but leavethe off. thermostat housing pressure cap you can feel the upper radiator hose getting hot. Watch out for the engine fan. 8. By this time the coolant level inside the thermostat housing filler neck may be lower.If the level is lower, add more of the proper mix through the filler neckuntil the level reaches the base of the filler neck. it is properly inserted, then replace the pressure cap.At any time during this procedure if coolant beginsto flow out of the filler neck, reinstall the pressure cap. Be sure thearrows on thepressure capline up like this. How to Add Coolant to the Coolant Surge Tank-3,IL V6 Engine If you haven't found a problem yet, but the coolant level isn't at FULL COLD, add a 50/50 mixture of clean water (preferably distilled)and a proper antifreeze at the coolant surgetank, but be sure the cooling system, including the coolant surgetank pressure cap, is cool beforeyou do it. (See Coolant in the Index for more informationabout the proper coolant mix.)