rad and coolant

[Wouter de Waal]

>Only some of the later model engines use dual-acting or bypass
>thermostats. Toyota used them in the early Tercels, and Renault used
>them back in the little R12 - how much farther back I cannot say, but
>American engines up until very recently used standard, single acting
>stats, depending on pump pressure differences to make the water ignore
>the bypass hose when the stat opened.

I would say that an open thermostat would provide a different back-pressure
than no stat at all. And this would cause the water to maybe not ignore the
bypass hose. Leading to those cracked heads when the stat is removed.

This is pretty much what I was getting at in the first place - rather rip
the guts to turn the thermostat into "open all the time", if you remove the
stat you upset some delicate pressure/flow balances.

Making sense?

W