<html xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns="http://www.w3.org/TR/REC-html40">
<head>
<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii">
<meta name=Generator content="Microsoft Word 11 (filtered medium)">
<style>
<!--
/* Font Definitions */
@font-face
{font-family:SimSun;
panose-1:2 1 6 0 3 1 1 1 1 1;}
@font-face
{font-family:"\@SimSun";
panose-1:2 1 6 0 3 1 1 1 1 1;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman";}
a:link, span.MsoHyperlink
{color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{color:purple;
text-decoration:underline;}
p.MsoPlainText, li.MsoPlainText, div.MsoPlainText
{margin:0in;
margin-bottom:.0001pt;
font-size:10.0pt;
font-family:"Courier New";}
@page Section1
{size:8.5in 11.0in;
margin:1.0in 77.95pt 1.0in 77.95pt;}
div.Section1
{page:Section1;}
-->
</style>
</head>
<body lang=EN-US link=blue vlink=purple>
<div class=Section1>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> The</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> flow rate of the fluid through the heat exchanger does not affect
how much</span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>> heat is transferred.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>I disagree. As the fluid cools during it's trip through the
exchanger, the delta-T across the exchanger drops, causing less heat to be
transferred. So the slower the flow, the more delta-T drops and less heat
is transferred. In the extreme case of no flow at all, the fluid temperature
drops until delta-T is zero and no further heat is transferred. If this
were not true, the thermostat could not regulate engine temperature.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>But of course, that says that faster flow can only increase heat
transfer (up to a point), not reduce it. However, there is another
problem that can arise, and IMO is the root of the old myth about coolant
flowing "too fast".<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>The radiator presents a significant restriction to coolant flow,
meaning there is a pressure differential across it when coolant is flowing.
To increase the flow requires more pressure. But the pressure cap is on
the high side of the radiator (and is only 4 psi on the earlier TRs). So,
if the pressure drop across the radiator (aka head) becomes high enough, the
pressure cap will open and release coolant from the system. Obviously,
lack of coolant results in overheating, but the coolant loss came first. FWIW,
this problem is mentioned at the bottom of <a
href="http://stewartcomponents.com/index.php?route=information/information&information_id=11">http://stewartcomponents.com/index.php?route=information/information&information_id=11</a><o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>A related problem can happen even without coolant loss; namely the low
side pressure goes enough below atmospheric to collapse the return hose (or
hoses for TR2-4A). I used to own an Oldsmobile V8 that suffered that
problem; which GM had solved by putting a reinforcing spring inside the lower
hose. If you had the wrong hose fitted (ie a generic replacement instead
of the GM specified hose), you could actually see it collapse just by buzzing
the engine to redline.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>Yet another issue with the early TR motor is the original aneroid type
thermostat. It relies on a heated gas expanding a bellows to open the
thermostat valve. But, the bellows is also exposed to pressure from the
water pump, which tends to force it closed.<o:p></o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'><o:p> </o:p></span></font></p>
<p class=MsoPlainText><font size=2 face="Courier New"><span style='font-size:
10.0pt'>-- Randall<o:p></o:p></span></font></p>
</div>
</body>
</html>