Please let me clarify an apparently common misunderstanding regarding
heat transfer. The statement being made that the rate of heat transfer
is higher if the fluid flow is slower is incorrect and excactly the
opposite of what actually occurs. Heat transfer is increased with higher
fluid flow rates! This is true both for the radiator fluid to radiator
surface and engine interfaces and for the radiator surface to air
interface. Thus increased capacity water pumps and fans will increase
cooling capability even though the radiator has not been changed.
Likewise, when engine temperature increases the thermostat opens ... thus
increasing the fluid flow rate and velocity to increase the cooling rate
and lower the temperature! That being said - maintaining correct engine
operating temperature with a thermostat as has been stated - is
important! Not only to keep the engine from overheating but rather to
keep it from running to cool which has adverse affects on engine
lubrication and combustion efficiency.
Andrew Somerville
Mechanical Engineer and Bricklin owner
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From: George J. Malaska[SMTP:bricklingeorge@email.msn.com]
Sent: Wednesday, August 18, 1999 5:53 PM
To: Bricklin
Subject: COOLING SYSTEM
Gregg was right, you should have a thermostat in the engine. It can not
cool properly if the coolant is not slowed down enough to have the heat
dissipated in the radiator. Also, 210 degrees is not pushing it. I worry
when it gets to 220 and above. If you have the proper mix of
coolant/water
and a good pressure in the system, the boiling point is actually closer
to
250.
The best way to ensure that your car runs cool is to make sure the
system
is clean, and the t-stat is operating correctly( I run a 180 in mine). If
the water pump is more than a couple of years old I would consider
replacing
it, especially if you do not drive the car alot. The impeller vanes can
be
eaten by corrosion (actually cavitation).
Hoses are just as important. If mushy, they can collapse and restrict
flow.
The radiator is the most important part of the system. Some people have
gone
to a 4 row core as opposed to the standard 3 row. Not a good move, in my
experience, as the passages are smaller and tend to clog easier. I have
had
the best success with a 3 row. Ask your local radiator shop to get you a
high effeciency core. The fins-per-inch is what matters the most. A stock
Bricklin radiator had 10 fins per inch. The HE has 16 fins-per-inch, so
you
can dissipate more heat in the same amount of space.
Make sure that you fan clutch is working properly also. You should hear
a
roar when cold and the noise die off as the engine heats up and then hear
it
come and go as engine temp rises and falls. There are thermostatic fans
and
then there are viscous drive fans that are governed by engine speed
rather
than temp. They tend to be noisier at speed but they do a good job of
cooling.
I have also heard, but have not tried, that spacing the A/C condensor
out
at the bottom helps, as this is where most of the air comes in, from
under
the bumper and the air dam. I installed new hoses, radiator, t-stat and
rad.
cap and ran my car in 98 degrees this summer with the air on and it did
not
go over 210, even in heavy traffic.
One other reason that you need a thermostat is that the engine is
designed
to run in a certain temp. range, not only for fuel efficiency but to heat
the and cool the oil. If the engine runs too cold the condensation in the
crankcase can not be vaporized and sludge will form. Seen lots of that!
Just adding my 2 cents and hope it helps someone.
George.
George J. Malaska, VIN#768,#1548.
Membership Director, Bricklin International
Elkhart, IN. 219-875-1270
bricklingeorge@msn.com.
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