one last coolant vacuum refill question

[rojizostang]

Does the system need to be completely drained of coolant before pulling a vacuum, or can it be pulled on top of coolant that remains in the system?

 

[wabirch]

Radiator is recommended, here's what I followed.

INSTRUCTIONS FOR COOLANT FILL TOOL
Please read the following before using this tool:
• Install an air line nipple (not supplied) to the shutoff valve.(Note: Hold the
ball valve body assembly with a wrench during air line nipple installation to
avoid damage to the Venturi assembly)
• Install the cone adapter to the elbow fitting
• Push the furnished refill hose onto the barbed fitting on the coolant fill tool
• Minimum shop air required is 90 psi (6 BAR) and should have an air dryer
system
• NOTE: For best results, the radiators should be completely drained
• NOTE: In bus applications, it is recommended to close the heater shutoff
valves when initially draining the system
Refilling Instructions:
1. Insert the coolant fill tool cone adapter into the radiator service neck or reservoir
tank.
2. Make sure the refill hose valve (blue lever) is closed. (Fig.1)
3. Insert the filter end of the refill hose into the coolant container. It is
recommended to draw from more coolant than required. (Fig.2) NOTE: Models
equipped with an additional overflow tank require that hoses to the tank be
clamped shut prior to the next step.
4. Connect shop air to the Venturi assembly and then open the ball valve (red
lever).You will hear a hissing noise as the tool begins to pull a vacuum.
5. With the ball valve (red lever) left open, open the refill valve (blue lever) slightly
and close as soon as coolant has filled the hose. (This is done in order to remove
air from the fill hose). At this time, the fill tool no longer needs to be monitored
and the vacuum gauge pointer will begin to rise after a short period. (Fig.3)
NOTE: Radiator and heater hoses may start to collapse. This is normal due to
vacuum draw.
6. Depending on the size of the cooling system, a typical gauge reading of 25 or
higher should be reached within 2 – 3 minutes. (The gauge reading may be
slightly less in higher elevations but a proper vacuum should still be reached
within 3 minutes).
7. Once the gauge has reached the desired vacuum level, close the vacuum air
supply valve (red lever) and let the system sit for 20 seconds to observe for a
drop in vacuum. A drop in the gauge reading indicates a vacuum leak in the
system.
8. Open the refill valve (blue lever) and the coolant will start to fill the cooling
system. A system without a vacuum leak will fill in about 4 minutes. (Fig.4)
NOTE: If the refill tube end comes out of the coolant during the refill process,
air will be pulled into the system and the entire procedure will need to be
repeated.
9. Disconnect the airline and remove the fill tool. NOTE: Overflow tanks should
be filled to proper level. Top off cooling system if necessary.

 

[86GT351]

Simple answer. As much as you can drain will be sufficient.

 

[rojizostang]

Ok thanks for the help

 

[travelers]

Simple answer. As much as you can drain will be sufficient.

Yep that's what I do.