Couldn't a blockage in the lines or an air pocket cause the same symptoms?
> On Tue, 30 Dec 2003, MacLachlan, Bill wrote:
>
> > Start the cold engine.  Let it run. As motor warms up, feel the radiator
> > surface. If its all stone cold, the thermostat ain't opened yet. Once
> > the thermostat opens and the radiator starts to warm up,  it should warm
> > up evenly all over. Clogged patches in the radiator will stay cold while
> > everything else warms up. If you've got an unevenly heating radiator,
> > you've got a clogged one.