98 sedan deville how to bleed cooling sistem - 2001 Cadillac DeVille

Radiator drain should be on the drivers side - remove the lower air shield to get at it.

could be your temostat, the water pump, blend door or motor, try the termostat first and then see what happens. try to bleed the cooling sistem too. maybe air in the sistem.

fuel pressure is probably bleeding off when it sets for a period. it probably is bleeding off into the return line if you see no leaks.turn the key on for 30 seconds then off before starting. if you dont like this then you can replace all of the fuel line o-rings in the system and pressure regulator/fuel rail assembly

The most common overheating problem with the Northstar engine is a blocked purge line(small hose).The purge line is designed to purge air out of the cooling system.
There is a small diameter hose coming from near the top of the coolant tank (not the cap) ,this is the purge line.
With the engine idling,pull the purge line from the tank,if there is no coolant flow from this small hose,it is blocked and this will cause overheating.
If the hose is clear, check for blockage at the nipple on the tank.Or trace the hose back until you find the blockage.
The hose goes in to the engine to a crossover and comes out the other side close to the thermostat housing,the blockage may be there.

I would check the fuses, and check to see if you are getting power to the fuel injectors.

if the car overheats all the time, idle and driving, then check the water pump

if the car only overheats at idle, check the cooling fan

check the master cylinder. It may need to be replaced.. When replacing, make sure to bench bleed it as not doing so would void the warranty.

pull bottom rad hose it will drain. You might need to replace your thermostat there might be a vapour lock also you should have a screw in your cooling system somewhere for bleeding it(letting the air out)

Have you checked your oil pump and made sure all lines were reinstalled?

It could be related to the exhaust pipes/ and or shields cooling down