Well, the only other thing I can think of is to find a local auto parts store (like Halfords) and get yourself some of this.

http://www.halfords.com/webapp/wcs/s...egoryId_165750

Set up a small loop with just the rad and pump and let it run for a bit. I have no idea what that stuff would do to acrylic so it'd probably be smart to leave all acrylic out of that loop.