The vans with the 3.4L engine have a couple of bleed screws for the cooling system (see attached link for locations).
When the engine is cool, fill the cooling system at the radiator cap, with the bleed screws open slightly. When coolant starts to come out, close the screws quickly, to keep a minimum of air getting back into the system.
Once full, also fill the overflow tank to at least half full, then start the engine and allow it to come up to normal temperature. Then allow it to cool off again. Do this a few times over the next couple of days, and keep an eye on the overflow tank, always keeping it about half full. The action of the the overflow tank being emptied and refilled, as the coolant expands and contracts (with temperature changes) will also help to bleed ALL of the air out of the system.
Once the cooling system is full and has gone through a few cycles, then it should stay full and no more air should get into the system. If you find more air getting in, then you have other issues to look into.
Good Luck, Greg
pop the radiater cap off and let the van engine run for 30 minutes. this will burp out any air in the cooling system and your engine will not overheat then. afterwards, fill the radiater back up as needed.
There is a screw right on top of the line about in the center of the engine (maybe a bit to the right as you are looking at it). Loosen it and let the air out, when fluid starts to come out, tighten it back.
Remove coolant cap, allow engine to get to operating temperature, turn on heater full blast and patiently wait for air to escape system.
If this is for an S-Series, you don't have to, The system has a deairiation line and does it on its own.
You need to burp the radiator and cooling system.
It should have a bleeder screw on top of the thermostat housing.
The cooling system on a 2001 Mitsubishi Eclipse GT can be burped by gently squeezing the upper radiator hose. Keep topping the overflow tank until the air is purged.
burp the water system that may help
Locate the plug on the bottom of the radiator to drain it. Put some radiator cleaner in and drain it again.
You carefully remove the top coolant hose to the heater, not totally off, just enough so air can get out.
you need to burp the cooling system
A sulphur burp, or rotten egg burp is the expulsion of sulphur dioxide from your system, usually a result of a gastro bug but sometimes something more serious.