I stuck a hose in every hole I could find until everything ran clear.
Edit: Your DIY is close but you are supposed to fill it with the heat on full blast.
Matte Black Kidney Grilles | Smoked Tails & Corners | Mtech II Bumper | Hotchkis Springs | ACS Roof Spoiler | M3 Spoiler | 20% Tint
WTB: Black sun visors & grab handles - PM ME!
I have P.A. Soft and a 20-pin adapter. Only used it a few times but pm me if you need anything coded!