I have recently attempted to bleed the air from my radiator. My heads leak
when it is cold. The dripping stops when the motor heats up. I bled the
system according to the Bently manual and advice from the list. I took it
for a short road test (2 miles) and the gauge went bonkers again. I
immediately pulled over and loosened the radiator screw. Air came out
after bleeding the system for a half hour. I drove again for about a mile
and again the gauge went off again. It seems that I either did not get all
the air out or it is getting in from some place else, heads perhaps? I
just nedd to patch this together to get me about 500 miles ( new motor)
any advice? Stopping every three miles makes for a long trip anywhere, and
I don't want to smoke the motor. I have some Barsleaks but have not
experimented with it yet. 
-mike             busted flat in cow Hampshire