"Alek" wrote in :

NO NO !!! ...keep going.......What happened AFTER U nudged the Rad
Cap....????


Well, because RT's had that big knurled rad cap you could nudge it round
with a bakelite board and the cooling system (which wasn't pressurised in
the way things are today) would boil dry much faster. You had to use the
board because the RT's cab was too cramped to be able to reach the rad cap
with your hand. There was no risk of losing the cap because it was chained
inside the rad.