Return-Path: Sender: (Marvin Kaye) To: flyrotary Date: Tue, 17 Dec 2002 00:45:10 -0500 Message-ID: X-Original-Return-Path: Received: from ncsmtp02.ogw.rr.com ([24.93.67.83] verified) by logan.com (CommuniGate Pro SMTP 4.0.2) with ESMTP id 1913196 for flyrotary@lancaironline.net; Mon, 16 Dec 2002 21:26:11 -0500 Received: from mail7.carolina.rr.com (fe7 [24.93.67.54]) by ncsmtp02.ogw.rr.com (8.12.5/8.12.2) with ESMTP id gBH2PYut020488 for ; Mon, 16 Dec 2002 21:25:34 -0500 (EST) Received: from o7y6b5 ([24.25.85.184]) by mail7.carolina.rr.com with Microsoft SMTPSVC(5.5.1877.757.75); Mon, 16 Dec 2002 21:24:16 -0500 X-Original-Message-ID: <002401c2a574$8f99b5c0$1702a8c0@WorkGroup> From: "Ed Anderson" X-Original-To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] water pressure X-Original-Date: Mon, 16 Dec 2002 21:32:36 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0021_01C2A54A.A69A7AE0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_0021_01C2A54A.A69A7AE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hard to say, Peter You may have a problem or may not. After some flights my coolant = pressure will remain at 7-10 psi for days or even weeks, other times it = goes down as soon after I shut down the engine. I also have my coolant = pressure go as high as 20 psi on start up (long before the coolant would = be hot enough, you would think). My first thought was that I had a leak = in one of the coolant "O" rings that was permitting the combustion gases = to pressurize the coolant system. =20 I have now been flying with those conditions for over 80 hours. = However, on this engine (91 turbo II) there has been no lost of coolant = and the pressure drops to an average of 5-7 psi in flight and sometimes = when the coolant and oil temps drop below 160F - no coolant pressure = shows (I do not have a thermosat). By increase the power/rpm the temps = will rise and the pressure gauge will start showing pressure again. My theory (so you know what that is worth) is that if you have been = successfull in evacuating all the air from the coolant system then you = have essentially an incompressible liquid left (actually, there is still = a small amount of air remaining, in solution with the coolant, if = nowhere else). So I believe even the the coolant pump running could = create pressure readings depending on where you have your sensor. I = notice that if the pressure is up around 20 psi immediatly after = starting the engine and (after warming the engine up) I reve it to 5200 = rpm that the coolant pressure drops to 5-7 psi while at the higher rpms. = It would seem to me that if the pressure I am seeing on start up were = truly combustion gases leaking past the "O" ring then at 5200 rpm the = pressure should increase - not decrease. Plus the fact that the coolant = pressure when flying is never higher than 15 psi leads me to believe = that this may not be a problem as it first seems. Now I could be all wet with this theory, but I would look for other = signs of a true problem. Are you seeing any green coolant leaks around = your intake or exhaust system. Any signs of bubbles or exhaust smell = when you open your radiator cap?? Etc. The reason I think the pressure decreases (In my installation)when I = reve the engine is that I have my pressure sensor in my header tank. My = header tank ties in to my coolant line with a "T" just before the pump = intake. So I believe that the flow of high speed coolant past the = opening of the "T" tends to create a low pressure area in the header = tank where my sensor is located. On a previous engine (an 86 NA) I did develop a coolant "O" ring leak = when I badly ( and several times) overheated the engine. It caused me = to slowly lose coolant at a gradually increasing amount on each flight = and eventually forced me to tear down the engine. Also, green coolant = began leaking from my exhaust pipe which cinched the diagnosis of a = coolant "O" ring problem. I found the leak next to the exhaust port in = the inner coolant "O" ring. So after that I went with the Tefolon = Coated Silicon "O" rings from Hayes and believe they have held up. So don't know if my experience helps any, but there you have it for what = it may be worth. Ed Anderson ----- Original Message -----=20 From: Peter Cowan=20 To: Rotary motors in aircraft=20 Sent: Monday, December 16, 2002 8:53 PM Subject: [FlyRotary] water pressure Today I'm seeing some different characteristics in the water pressure = readings. Used to be that after cooling down I could see 4 or 5 lbs = pressure for many days and I don't think increasing pressure after start = up was tied to rpm. Now pressure drops instantly on shutdown and is = closely tied to rpm to max of 15lbs as the engine is reved up. This = looks bad to me although temps in flight are fine. What do you think? Peter ------=_NextPart_000_0021_01C2A54A.A69A7AE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hard to say, Peter
 
   You may have a = problem or may=20 not.   After some flights my coolant pressure will remain at = 7-10 psi=20 for days or even weeks, other times it goes down as soon after I shut = down the=20 engine.  I also have my coolant pressure go as high as 20 psi on = start up=20 (long before the coolant would be hot enough, you would think).  My = first=20 thought was that I had a leak in one of the coolant "O" rings that was=20 permitting the combustion gases to pressurize the coolant system. =20
 
    I have now been = flying with=20 those conditions for over 80 hours.  However, on this engine (91 turbo II) there has been =  no lost=20 of coolant and the pressure drops to an average of 5-7 psi in flight and = sometimes when the coolant and oil temps drop below 160F - no coolant = pressure=20 shows (I do not have a thermosat).  By increase the power/rpm the = temps=20 will rise and the pressure gauge will start showing pressure = again.
 
My theory (so you know what that is = worth) is that=20 if you have been successfull in evacuating all the air from the coolant = system=20 then you have essentially an incompressible liquid left (actually, there = is=20 still a small amount of air remaining, in solution with the coolant, if = nowhere=20 else).  So I believe even the the coolant pump running could create = pressure readings depending on where you have your sensor.   I = notice=20 that if the pressure is up around 20 psi immediatly after starting the = engine=20 and (after warming the engine up) I reve it to 5200 rpm that the coolant = pressure drops to 5-7 psi while at the higher rpms.  It would seem = to me=20 that if the pressure I am seeing on start up were truly combustion gases = leaking=20 past the "O" ring then at 5200 rpm the pressure should increase - not = decrease.=20 Plus the fact that the coolant pressure when flying is never higher than = 15 psi=20 leads me to believe that this may not be a problem as it first=20 seems.
 
 Now I could be all wet with this = theory, but=20 I would look for other signs of a true problem.  Are you seeing any = green=20 coolant leaks around your intake or exhaust system.  Any signs of = bubbles=20 or exhaust smell when you open your radiator cap?? Etc.
 
The reason I think the pressure = decreases (In my=20 installation)when I reve the engine is that I have my pressure = sensor in my=20 header tank.  My header tank ties in to my coolant line with a "T" = just=20 before the pump intake.  So I believe that the flow of high speed = coolant=20 past the opening of the "T" tends to create a low pressure area in the = header=20 tank where my sensor is located.
 
On a previous engine (an 86 NA) I did = develop a=20 coolant "O" ring leak when I badly ( and several times) overheated = the=20 engine.  It caused me to slowly lose coolant at a gradually = increasing=20 amount on each flight and eventually forced me to tear down the=20 engine. Also, green coolant began leaking from my exhaust pipe = which=20 cinched the diagnosis of a coolant "O" ring problem. I found the leak = next to=20 the exhaust port in the inner coolant "O" ring.  So after that I = went with=20 the Tefolon Coated Silicon "O" rings from Hayes and believe they have = held=20 up.
 
So don't know if my experience helps = any, but there=20 you have it for what it may be worth.
 
Ed Anderson
----- Original Message -----
From:=20 Peter = Cowan=20
Sent: Monday, December 16, 2002 = 8:53=20 PM
Subject: [FlyRotary] water = pressure

Today I'm seeing some different = characteristics=20 in the water pressure readings. Used to be that after cooling down I = could see=20 4 or 5 lbs pressure for many days and I don't think increasing = pressure after=20 start up was tied to rpm. Now pressure drops instantly on shutdown and = is=20 closely tied to rpm to max of 15lbs as the engine is reved up. This = looks bad=20 to me although temps in flight are fine. What do you = think?
Peter
------=_NextPart_000_0021_01C2A54A.A69A7AE0--