Whenever I get access to that area of the block I remove the plug (sometimes
have to drill it out) and put in a drain cock. I try to find one that you can
attach a tube to so you can drain it where you want to.
The 122s mostly do have a drain valve on the radiator but like the others say you
usually have to drain the radiator by loosening the lower hose.
If you don't have a block drain the easiest way to get it drained is to drain the
block is to drain the radiator first, which will drain the water down to the level
of the top surface of the block. Then remove the water outlet and thermostat and
get about a 6-foot piece of 1/4" OD plastic tubing. With some probing you can fit
it down through the water jacket to nearly the bottom of the jacket and siphon the
coolant out. First time will be the hardest as there is no substitute for experience.
Best way to siphon is to figure out where the water passages are, then fill the tube
with water, put your thumb over the outboard end and put the other end down into the
jacket, lower the outboard end into your bucket (well below the surface) and it will
siphon slowly out.
--
George Downs, Bartlesville, Heart of the USA!