Pontiac 2005 Bonneville Owner's Manual page 304

3. Remove the 3800 Series II V6 engine cover shield
to access the bleed valve.
3.1. Clean the area around the engine oil fill tube
and cap before removing. Twist the oil fill
tube, with cap attached, counterclockwise
and remove it.
5-44
3.2. Lift the engine cover shield at the front, slide
the catch tab out of the engine bracket and
remove the cover shield.
3.3. Put the oil fill tube, with cap attached, in the
valve cover oil fill hole until you are ready to
replace the cover shield.
4. After the engine cools,
open the coolant air
bleed valve. There is
one bleed valve.
It is located on the
thermostat housing.