Sounds to me like a Thermotime Switch (Thermostat Housing) ain't shutting
off when the coolant temperature reaches the proper threshold.  We have
had 4 local customers come by the business with essentially the same
problem.  Had them check to see if the Termostat was operating (ie: not
stuck open all of the time).  Thermotime switch replacement fixed the
problem on 3 of them.  The 4th had other major problems - coolant leaks,
exhaust falling apart, O2 sensor probe totally burnt up and the cata
converter was plugged up too.

Gettin' ready to install a 2.1 into my 84 Westy.  Definitely replacing
the Thermotime switch while it's easy to get to with the engine out.  I
only wanna bleed this cooling system ONCE.

Jim
BusBoys1@juno.com
http://www.bus-boys.com