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From: "Bob Perkinson" <bobperk@bellsouth.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: RE: [FlyRotary] Re: Coolant Leak
Date: Sun, 26 Jun 2005 08:29:24 -0500
Message-ID: <DMEPKACEFFMIBMLLCJNOAEGIDCAA.bobperk@bellsouth.net>
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Importance: Normal

If there is a closed liquid circuit that is completely void of air and a
pump is added to the circuit, the energy that is applied to the pump
impeller will show up first as pressure and then heat due to the slippage in
the pump.  If allowed to run without dissipating the heat a noticeable
temperature rise will occur.  I would think that it would be normal to see
coolant pressure at the pump discharge, with measurable pressure drop
through out the system until it reaches the pump suction.  If you could spin
the water pump on the engine without starting it , after a while there would
be a rise in temperature on the system it may not be much but it would be
there.  The guys that are using electric water pumps may well be able to pre
heat the engine running the water pump, it may take all day though.{:>)

Bob Perkinson
Hendersonville, TN.
RV9A N658RP Reserved
If nothing changes
Nothing changes


-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]On
Behalf Of Ed Anderson
Sent: Sunday, June 26, 2005 7:52 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Coolant Leak


 >
> 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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