So, would it be better to remove some coolant and HAVE a cushion of air, and
thereby reduce the pressure and stress on cooling system components? I have
a heater core up front. I'd hate to have it burst. Is it really seeing 20+
PSI when it was probably designed to take less?
John

>  >
> > This may be related to Al Wicks reason for running with a cup of air
> > trapped in his system, a buffer if you will.....Tim Andres
> >
> I do notice that after I have refilled the coolant system (and before the
> air is all flushed out), that I do not get the immediate surge of
> pressure
> to 21-24 psi on start up.  It will slowly climb to 8-12 psi depending on
> power settings and airspeed.    However, after several flights and the
> system is purged of air this phenomena starts to occur.  Again,
> no coolant
> leak associated with it.  I suspect that with the air purged, that this
> surge has to do with the coolant volumetric area.  With no
> cushion, then any
> movement of coolant is likely to be sensed as a pressure increase
> - once the
> block has warmed up and coolant passages, etc, have warmed up (and
> expanded), I think there is a slight increase in coolant passage
> volume and
> the pressure decrease as a results.  Just a SWAG of course.
>
> Ed A
>
>
>
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