2007 Buick Rendezvous Owner's Manual - Page 385

If you hear a hiss, wait for that to stop. A hiss means there is still some pressure left. 2. Then keep turning the pressure cap, but now push down as you turn it. Remove the pressure cap. {CAUTION: You can be burned if you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Do not spill coolant on a hot engine. Housing Bypass Tube 3. After the engine cools, open the coolant air bleed valves. There are two bleed valves. One is located on the thermostat housing. The other is located on the thermostat bypass tube. 385