X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.2.0) with ESMTP id 2756423 for flyrotary@lancaironline.net; Mon, 25 Feb 2008 08:00:22 -0500 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([75.191.190.141]) by cdptpa-omta06.mail.rr.com with SMTP id <20080225125941.SJQZ13780.cdptpa-omta06.mail.rr.com@edward2> for ; Mon, 25 Feb 2008 12:59:41 +0000 Message-ID: <002101c877ae$49ee54b0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Water pressure Date: Mon, 25 Feb 2008 07:59:42 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001E_01C87784.60D7E850" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_001E_01C87784.60D7E850 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Bob, if there is no air in your coolant system, you may be observing an = hydraulic lock type phenomena. My water pressure will immediately zoom = to 21 psi on engine start up. As the engine warms up the pressure drops = back down. My understanding is that with no air and the incompressible = nature of a liquid - that even small perturbations anywhere in the = system can cause the sensor to signal pressure. As the engine warms and = a very small amount of expansion in block, rad cores, lines etc. happens = that is enough increase in volume of the "containment" for the pressure = to lower. This is why some folks recommend leaving a small amount of air under the = cap. If you are not seeing oil in your coolant or bubbles then its = unlikely you have a busted O ring. Ed ----- Original Message -----=20 From: BMears9413@aol.com=20 To: Rotary motors in aircraft=20 Sent: Sunday, February 24, 2008 11:52 PM Subject: [FlyRotary] Water pressure I ran my 20B at idle, till about 160 degrees. My water pressure rose = up to 23 lbs. That seems excessive to me, but I've never watched water = pressure before. I've bled the block a couple of times and I dont feel = like I have an air lock. Heat is even throughout the radiator. I was a = bit worried about compression leaking into the cooling chamber, but I'm = not loosing any water, the plugs aren't wet, and it starts flawlessly = each time. Hot or cold. Recon I'm all worried about nothing? Bob Mears=20 Supermarine Spitfire -------------------------------------------------------------------------= ----- Delicious ideas to please the pickiest eaters. Watch the video on AOL = Living. ------=_NextPart_000_001E_01C87784.60D7E850 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Bob, if there is no air in your coolant system, you = may be=20 observing an hydraulic lock type phenomena.  My water pressure will = immediately zoom to 21 psi on engine start up.  As the engine warms = up the=20 pressure drops back down.  My understanding is that with no air and = the=20 incompressible nature of a liquid - that even small perturbations = anywhere in=20 the system can cause the sensor to signal pressure.  As the engine = warms=20 and a very small amount of expansion in block, rad cores, lines etc. = happens=20 that is enough increase in volume of the "containment"  for = the=20 pressure to lower.
 
This is why some folks recommend leaving a small = amount of air=20 under the cap.  If you are not seeing oil in your coolant or = bubbles then=20 its unlikely you have a busted O ring.
 
Ed
----- Original Message -----
From:=20 BMears9413@aol.com
Sent: Sunday, February 24, 2008 = 11:52=20 PM
Subject: [FlyRotary] Water = pressure

I ran my 20B at idle, till about 160 degrees. My water pressure = rose up=20 to 23 lbs. That seems excessive to me, but I've never watched water = pressure=20 before. I've bled the block a couple of times and I dont feel like I = have an=20 air lock. Heat is even throughout the radiator. I was a bit worried = about=20 compression leaking into the cooling chamber, but I'm not loosing any = water,=20 the plugs aren't wet, and it starts flawlessly each time. Hot or cold. = Recon=20 I'm all worried about nothing?
 
Bob Mears
Supermarine Spitfire



Delicious ideas to please the pickiest eaters. Watch the video on AOL=20 Living.
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