Wanted to pass along that I've done two coolant refills in the last week (two K04 big wheel installs) with zero issues. After reading about the issues with getting air out of the coolant system and reading up on the various methods I ordered a vacuum refill tool.
$70 and I didn't have to cut, install, modify, or even open and coolant lines in any way.
The tool comes with several rubber nipples. The conical one works best with the Kappa surge tank.
Here is the procedure we followed, and some notes:
1. Install conical nipper on main valve assembly of the tool.
2. Connect the Venturi assembly to the main assembly of the tool.
3 Insert firmly in tank (support tank from under side).
4. Turn large knob on tool to expand the nipple and seal the system.
5. Connect to compressed air, open compressed air valve on Venturi assembly to start air flow.
6. Open main assembly valve to Venturi. You should almost immediately see a vacuum drawing down. In about 30 seconds or so it should reach -25.
7. Close Venturi valve on main assembly. Do this BEFORE the next step.
8. Turn off compressed air valve at Venturi assembly.
9. Wait five minutes or so to make sure vacuum holds. This is a good time to prep new coolant. Mixing it in a CLEAR container is very helpful. Six or more liters in size is ideal, but I used a 1 gallon.
10. Assuming vacuum holds, insert the coolant hose from the main assembly into the new coolant container.
11. *Slowly"* open the coolant valve on the main assembly until coolant fills the hose (to eliminate the air).
12. Close the coolant valve on the main assembly once the line is full of coolant. Minimize the amount that enters the tank.
13. Now we want to remove the air that entered the system from the coolant line. Open the compressed air valve at the venturi assembly (do this BEFORE the next step).
14. Open the main assembly valve to the Venturi to draw out the little bit of air that got in from the coolant line. Run for 30 seconds or so.
15. Close Venturi valve on main assembly. Do this BEFORE the next step.
16. Turn off compressed air valve at Venturi assembly.
17. Slowly open the coolant valve at the main assembly. It sucks the coolant into the tank FAST. Do not let the coolant container level get low; you do not want to suck air into the system. This is where the clear container is helpful.
18. If the vacuum gets low before the surge tank is half full, or your container gets low, close the coolant valve at the main assembly. Refill your coolant container as needed. If needed, repeat steps 13-16 to draw down more vacuum. You may get some coolant sputtering out the compressed air line now. That's okay.
19. Repeat steps 17-18 as needed until the surge tank is half full.
20. Close the coolant valve at the main assembly.
21. Slowly open the Venturi valve at the main assembly to let air back into the system. Some bubbling here is normal.
22. When the pressure has equalized, turn the large knurled knob and release the entire tool from the surge tank.
23. Note coolant level. Fill to halfway as needed.
24. Start car. Monitor surge tank level, temp at the DIC, and watch for leaks wherever you disassembled.
25. Assuming no leaks and stable coolant level, take car for slow test drive. IMPORTANT: In both cars we did, the temperature spiked to the 230-245 range ONCE (not high enough to trigger a temp light), stayed there for a few minutes then dropped to normal. My car has about 100 miles on it now without any further issues other than topping off the surge tank.
Don't be intimidated by 25 steps here: I tried to be thorough. This is a pretty simple process; the most difficult part the first time was selecting the correct nipple and that I goofed and reversed steps 15 and 16, letting air back into the system.
One more note: Dexcool compatible concentrate was $18 a gallon at our local parts store. 50/50 was $16.