Radiator Cap

[Johnny]

John Hess wrote:
> 
> The restrictions on the pump pressure are reduced,  thus pressure is
> reduced at the input to the radiator.  This is not debatable;  but, it
> IS measurable!

But there is a good size hose that bypasses the whole time, as well as
the heater core too. In fact, the bypass and the heater hose are bigger
than the opening in the thermostat, when combined. But all of that is
refering to the block side of the system, as compared to the inlet of
the radiator. However, with the 21psi cap on there, The whole system
should be showing close to that much pressure. The working pressure of
the pump is kinda pale in comparison. It doesn't take much to stop the
flow. High volume, low pressure. I would think that with the bypass and
the heater core, coupled with the closed system static pressure, you
would have a hard time being able to measure by pressure at the top hose
a variation when the thermostat opened and closed. There would have to
be some pressure drop accross the radiator in order to get the water to
flow through it, but in the scope of the whole system, I am having a
hard time believing that it is going to make the difference of it
boiling over or not.

Even if it did make a big difference, as soon as the water did get up to
a higher temp, it would just build more pressure. A system that is that
marginal is going to have trouble besides a psi or two.

-j-