All are pressurised systems, the expansion tank allows a higher rad
line/lower bonnet line i.e. when the rad was moved right forwards, and the
expansion tank still has an overflow. The expansion in earlier systems is
taken up by the large space at the top of the rad above the tubes. Both
dump on the ground if overfilled, but if you use an unpressurised catch-tank
and a rad cap with a double seal (standard in the UK) the system will suck
back any overfilling overflow as it cools, but if you don't overfill it it
doesn't need it.
----- Original Message -----
Sent: Friday, May 28, 2004 10:45 PM
Subject: Re: Hot weather overheating
> Early CBs did not have an expansion tank, as the radiator was not a
> closed cooling system.