Mailing List flyrotary@lancaironline.net Message #5148
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] evap core air pockets?
Date: Tue, 6 Jan 2004 22:45:10 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Message
 
----- Original Message -----
Sent: Tuesday, January 06, 2004 5:50 PM
Subject: [FlyRotary] evap core air pockets?

Greetings,
 
In thinking about my evap core installation, I realized that there would be a potential problem with air getting trapped in the top of the cores.  Since the hoses are all on the bottom, it just seems like there's always going to be some air trapped at the top, unless I find some way to bleed it out. 
 
Ed, I just looked at your pics again, and don't see any provision to remove air from the top of your cores.  Is this not really a problem?
 
Thanks,
Rusty (really leaving now)
 
Well, yes and no.  You are correct when initially filling after a drain, you will find that approx 1/4 -1/3 of the upper core is filled with air.  A peacock would of course release the air, but I never installed any.   However, I have a proceedure that works and since I don't drain the coolant but once a year (intentionally that is), here is the proceedure I use.
 
Fill up the system with as much coolant as it will hold (this will leave air trapped as I mentioned - but not to dispare) -  fire up the engine and let idle with the radiator cap off.  Let it run for 1 to  1 1/2 minutes, then shut it down.  You will find that the system will now take more coolant.  Do this a couple or three times never running it for over tw0 minutes at a time and refilling the system each time. 
 
Then put the radiator cap on and fire up the engine again.  This time run it up to max rpm for apporx 30 seconds and then shut it down.  You should find your header tank again low on coolant.  A couple of more runs up to max static held for not more than 30 seconds and refilling will remove the air in the cores.
 
First time you run it up and after shutting it down hold your hand on the side tank of a core.  You can tell where the coolant level it very easily.  It will be much cooler immediately above the water level in the core and much warmer/hotter where the coolant is in the core. So you can monitor your progress in removing air by feeling the side tank for the temp differential line.
 
Note: DO NOT PLACE RELIANCE ON YOUR COOLANT TEMP SENSOR while doing this.  It will not register the correct temperature unless it is in steady contact with the coolant which it won't be until you get most of the air out.  So don't be lulled into letting the engine run longer than I suggested just because the temperature gage says everything is OK.
 
Hope this helps.
 
Ed Anderson
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