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Date: Sun, 26 Jun 2005 10:29:44 -0700
From: Tim Andres <tim2542@sbcglobal.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Coolant Leak
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Ed Anderson wrote:

> >
>
>> 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
>
>
>>>  Homepage:  http://www.flyrotary.com/
>>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>>
>
>
Keep in mind the total incompressibility of liquid, in an air free 
system 1 additional drop of water can send the pressure skyrocketing. 
The only expansion room available is probably your hoses then the cap. 
                        
Tim A