The little bleed hole is used for getting the air out of the system. Open it
up and shut it when coolant starts coming out.

Your description sounds more like a restricted heater core. Is one of the
heater hoses a bit cooler that the other one at the firewall? You may need
to flush the core and see if you can get some of the gunk out.

Denny

i disconnected the heater core and flushed it for 15 minutes (both
directions) and when i hooked the lines back up and cranked the truck the
air was colder than before.  i found this to be very odd, and opened my
reservoir to find that it was still topped off, despite running the truck
for a good 15 minutes after it warmed up.  i removed the bleeder screw on
the housing and saw the water was low.  i pulled the hose to the reservoir
off at the cap and blew and it was plugged.  after blowing really hard the
obstruction finally gave (and splashed anti-freeze all over me) and i hooked
it back up.  i ran the truck awhile and the reservoir dropped and the truck
finally gets hot.  although my reservoir was full, the cooling system was
ultimatley low.