Mailing List flyrotary@lancaironline.net Message #24508
From: John Slade <sladerj@bellsouth.net>
Subject: RE: [FlyRotary] Re: Coolant Leak
Date: Sun, 26 Jun 2005 09:07:50 -0400
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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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