X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from m12.lax.untd.com ([64.136.30.75] verified) by logan.com (CommuniGate Pro SMTP 4.3.4) with SMTP id 989457 for flyrotary@lancaironline.net; Wed, 08 Jun 2005 22:07:10 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.136.30.75; envelope-from=alwick@juno.com Received: from m12.lax.untd.com (localhost [127.0.0.1]) by m12.lax.untd.com with SMTP id AABBLRKA4AHC6X3S for (sender ); Wed, 8 Jun 2005 19:06:18 -0700 (PDT) X-UNTD-OriginStamp: L941HVjjYzDhN3itp//mkGjT3n7EbtyB/Ef/UmOso/XnsqAtnc+M6w== Received: (from alwick@juno.com) by m12.lax.untd.com (jqueuemail) id KUZ4L3BY; Wed, 08 Jun 2005 19:06:06 PDT To: flyrotary@lancaironline.net Date: Wed, 8 Jun 2005 19:05:25 -0700 Subject: Re: [FlyRotary] Re: coolant leak Message-ID: <20050608.190532.3460.6.alwick@juno.com> X-Mailer: Juno 5.0.33 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary=--__JNP_000_1bc9.5ff1.2e73 X-Juno-Line-Breaks: 8-6,8-9,14,19-20,25,29,34-37,42-51,53-54,57-58,61-62,63-32767 From: al p wick X-ContentStamp: 35:17:3308928240 X-MAIL-INFO:29f3f3c76aea1e178b9e0fc7a30fae37634aca0fda135eaa6adaca4adab3dac3730a9a3af3fac7cbc78a6a93ae4e8e9317eace0adb976bc7570aaee7476f475723dace6f1f7e2f1b1f X-UNTD-Peer-Info: 127.0.0.1|localhost|m12.lax.untd.com|alwick@juno.com This message is in MIME format. Since your mail reader does not understand this format, some or all of this message may not be legible. ----__JNP_000_1bc9.5ff1.2e73 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 8bit I've got sensors up the wazoo....some on my plane too. I record this info every few milliseconds. Calibrated sensors. So here is what I see. If I want my cooling system to operate at 24 psi, all I have to do is fill my swirl pot to the top with coolant. If I don't want it to see that high pressure, I just leave around a cup of air at the top of swirl pot. With my cup of air, it never exceeds 7 psi. Why? Air is compressible, coolant is not. When you first fire up engine, pressure is 0, relative to atmosphere. It takes around 8 minutes for pressure to slowly climb to 1 psi. The fluid level starts to rise too. All pressure increase is due to expansion of coolant due to heat. Coolant is not compressible, and can greatly increase force against the contained cooling system. After you shut off your engine, the 7 psi gradually drops over the next few minutes. It only takes around 12 minutes for the system to develop a vacuum relative to atmosphere. At that point the little valve in the radiator cap opens and allows fluid or air to flow into system. (Check out your rad cap, can you find both valves?) Logically, from that point on, you can't have a pressurized system. There is no added energy supplied to the system. With one exception: If you have compression leak into cooling system. But even that should have limited duration. Also, if you had a cooling sys that was normally under pressure, then none of the vehicles would be able to replenish their coolant. They rely on the atmospheric pressure to exceed the coolant pressure 12 minutes after shutdown. That's what forces that liquid in our "overflow" bottle to enter radiator. I'd double check my gage calibration if seeing pressure on startup. When I did ground testing with compression leak, this pattern would change. 1 second after full throttle, the pressure would jump to 24 psi, fluid level max out, temperature still cold. This would last for only 5 seconds. This entrained air then had profound effect on the entire cooling sys. I think that was the most interesting part. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 200+ hours on engine/airframe from Portland, Oregon Prop construct, Subaru install, Risk assessment, Glass panel design info: http://www.maddyhome.com/canardpages/pages/alwick/index.html On Wed, 8 Jun 2005 18:05:23 -0700 "Al Gietzen" writes: Some of the coolant is going to vaporize. This pressurises the system. Some of that vapor will never go back into solution so there should be pressure in the system even when cold. Dave; this may be the weak link in your logic chain. Why would some of the vapor not re-condense? I hope there is some other reason for the pressure. I’d hate for you to have to tear open the engine. Al Gietzen ----__JNP_000_1bc9.5ff1.2e73 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: quoted-printable
I've got sensors up the wazoo....some on my plane too. I record this = info=20 every few milliseconds. Calibrated sensors. So here is what I see.
 
If I want my cooling system to operate at 24 psi, all I have to do is = fill=20 my swirl pot to the top with coolant. If I don't want it to see that = high=20 pressure, I just leave around a cup of air at the top of swirl pot. With my= cup=20 of air, it never exceeds 7 psi. Why? Air is compressible, coolant is not.
When you first fire up engine, pressure is 0, relative to atmosphere. = It=20 takes around 8 minutes for pressure to slowly climb to 1 psi. The fluid = level=20 starts to rise too. All pressure increase is due to expansion of coolant = due to=20 heat. Coolant is not compressible, and can greatly increase force against = the=20 contained cooling system.
 
After you shut off your engine, the 7 psi gradually drops over = the=20 next few minutes. It only takes around 12 minutes for the system to develop= a=20 vacuum relative to atmosphere. At that point the little valve in the = radiator=20 cap opens and allows fluid or air to flow into system. (Check out your rad = cap,=20 can you find both valves?)
 Logically, from that point on, you can't have a pressurized= =20 system. There is no added energy supplied to the system. With one exception= : If=20 you have compression leak into cooling system. But even that should have = limited=20 duration.
Also, if you had a cooling sys that was normally under pressure, then = none=20 of the vehicles would be able to replenish their coolant. They rely on= the=20 atmospheric pressure to exceed the coolant pressure 12 minutes after = shutdown.=20 That's what forces that liquid in our "overflow" bottle to enter=20 radiator. 
 
I'd double check my  gage calibration if seeing pressure on=20 startup.
 
When I did ground testing with compression leak, this pattern would = change.=20 1 second after full throttle, the pressure would jump to 24 psi, fluid = level max=20 out, temperature still cold. This would last for only 5 seconds. This = entrained=20 air then had profound effect on the entire cooling sys. I think that was = the=20 most interesting part.

-al wick
Artificial intelligence in cockpit, Cozy IV powered by= =20 stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland,=20 Oregon
Prop construct, Subaru install, Risk assessment, Glass panel = design=20 info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html
 
 
On Wed, 8 Jun 2005 18:05:23 -0700 "Al Gietzen" <ALVentures@cox.net> writes:

 

Some of the coolant is going to= =20 vaporize.  This pressurises the system.  Some of that vapor = will=20 never go back into solution so there should be pressure in the system = even=20 when cold. 

 

Dave; this = may be=20 the weak link in your logic chain.  Why would some of the vapor not= =20 re-condense?  I hope there is some other reason for the pressure.&= nbsp;=20 I’d hate for you to have to tear open the engine.

 

Al=20 Gietzen

 

 
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