I tore my Ranco Leak-o-matic valve apart, removed the internal valve/stem, then reassembled it, sealing it permanently. It does not function at all (all of the coolant just passes right through), which is only slightly different than how they worked when brand new.
Carl

1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission