testing a heater core

["John F Sandhoff" <sandhoff@csus.edu>]

Is there a good way to test a heater core (out of vehicle) for
leaks? I have a couple of cores that I'm not sure of, and I'd like
to rebuild my heater with one that won't get my feet wet :-)

Local shops want about 40 bucks to test, which gets especially
painful if I have them test multiple cores. I'm especially concerned
about finding tiny leaks that would drip ever so slowly.

-- John
     John F Sandhoff   sandhoff@csus.edu   Sacramento, CA