HOT
AND BOTHERED!
Three-row radiator upgrade
Text and Photography by
Jim Langley and Chirag Asaravala |
 I
hate summer. I hate sweating through my shirt on hot black leather seats,
I hate steering wheels and shift knobs that blister your palms, I hate how
the AC blows hot air and robs the engine of horsepower. And most of all,
I hate the anxiety of sitting in traffic and watching the temp gauge creep
up to the top of the scale.
You're probably wondering why I'm bitching about the heat this late in the
year, but in the San Francisco Bay Area, this is the hottest time
of year. The strange weather patterns cook the inland valleys to triple
digits one week, then threaten them with rain the next. For the auto enthusiast
this time of year sucks even more, as the heat slows your car down at the
track, and makes driving miserable.
Both our '88 and '92 Mustangs were suffering from heat stroke on recent
trips to the drag strip. Sitting in two hours of stop-and-go traffic in
Sacramento's oppressive heat was enough to bring engine temps over the 200°F
mark -about the "N" in normal on the stock gauge.
At such a high temperature any hard stab of the throttle would result in
mild detonation, which is not beneficial to long engine life. With the radiator
not performing adequately not only is the engine running hot, but the driver
is also starting to cook, as the air-conditioning system condenser cannot
dissipate heat as effectively. An inspection the next day showed a radiator
core with mucho deposits and crud surrounding each and every tube. This
is fairly typical of any high mileage radiator.
An attempt at using a chemical flush was unsuccessful at removing the "bloom"
from the cross tubes, even though the instructions were followed to the
letter. We considered a professional high pressure flush and
rodding" out the cores, but at a cost of $60-75, plus the inconvenience
of dropping the car off at the shop, we figured it would be a better investment
to get a new radiator. It also made sense since we'd be putting a new motor
into the '88 project car. |
|
Cores,
Rows, and Fins
First a quick review of radiator construction and terms. Typically
a radiator will consist of two end tanks, either left and right or top
and bottom, and a center "core". The core consists of rows of
tubes which flow coolant either top to bottom (most early Fords), or horizontally
"crossflow", as is common on late model Ford radiators. Corrugated
fins serve to dissipate heat to the air passing through the radiator.
The tanks, tubes and fins can be copper/brass, aluminum or even plastic.
In most OEM passenger car applications the core will only have two rows
of tubes. This is usually fine for stock applications as long as the coolant
has unobstructed flow through the core.
 |
 |
A radiator core's internal water passages are referred to as rows.
A two-row radiator has two horizontal rows of cooling tubes stacked
parallel from the top to the bottom of the core (left); a three-row
core uses three rows of cooling tubes. (Aluminum-core radiators use
the term cell to describe their water passages.
Our stock two-core radiator was heavily corroded and scaled up. Note
the piece of RTV silicone blocking one of the tubes -a reason to use
the stuff sparingly when installing gaskets. The three rows of tubes
in our new radiator provide greater surface area for heat transfer. |
The fins,
which are thin metal blades fused to the rows or cells, carry heat away
from the water passages and dissipate the heat into the airstream flowing
through the core. A radiator's overall cooling efficiency is greatly influenced
by the number of fins per inch used in its core -- the more fins, the
better the core's ability to dissipate heat. Most standard OE radiators
use a core with 12 fins per inch; high-efficiency cores use 16 fins per
inch; high-performance aftermarket cores use a still higher number of
fins per inch. The cooling effect of a high-efficiency radiator is roughly
35 percent better than a standard-efficiency core.
|
The
Choices
After
doing some research we found a variety of replacement radiators available
for the Fox body Mustangs. The less-expensive OEM replacements are constructed
from copper/brass (copper fins and brass tubes), while the high-end units
are typically aluminum.
We were
interested in upgrading to a three-row radiator which would offer increased
cooling over the stock two-core. We ordered up two three-core radiators,
one manufactured by Modine and another by Go Dan Industries (GDI)
| '79-'93
Mustang 5.0L Radiators |
|
Radiator
|
#
Cores
|
Part
#
|
Material
|
CORE
THICKNESS
|
Approx
Cost* |
| Stock |
2 |
------ |
Cu/Br |
1.5" |
N/A |
| Modine |
3 |
1R2305 |
Cu/Br |
1.5" |
$200
(carparts.com) |
| Modine |
2 |
1R556 |
Cu/Br |
1.5" |
$130
(carparts.com) |
| Go-Dan |
3 |
433138 |
Cu/Br |
2" |
$129(Autozone/radiator.com) |
| Go-Dan |
2 |
433556 |
Cu/Br |
1.5"?
(not confirmed) |
$99
(Autozone/radiator.com) |
| |
| *At
time of publishing. Costs vary per region. |
The first
thing we noticed was the GDI 433138 was much thicker than the Modine 1R556
radiator. Both were three-row radiators, however the GDI radiator had
wider rows.Note how the core area matches the thickness of the end tanks.
Both types use copper-brass tubes. As a result the core thickness of the
GDI was two-inches, while the Modine was 1.5". Dimensionally both
radiators were the same exact height and width as stock. Both radiators
are also equipped with integral transmission fluid cooler for automatic
transmissions.
The
thicker GDI radiator did require cutting and modifying the rubber mounting
pads in the stock brackets. The Modine three-row dropped right in without
any need to modify the brackets.. We also noticed that the thicker core
on the GDI unit moved the fan and shroud one-half inch closer to the waterpump
pulley. While this did not pose any clearance problems with our Black
Magic electric fan, there would clearly be some interference with a larger
electric fan, such as the popular Lincoln Mark VII fans.
|
|
Is Aluminum
better?
Recently there has been a huge insurgence of aluminum radiators. While
aluminum certainly has its place, there really is no advantage in street
applications. While copper is approximately three times the density of
aluminum, but what is critical for optimal radiator operation is thermal
conductivity. As shown, copper fin's conductivity is 70% higher than for
aluminum fin.
| Copper/Brass
versus Aluminum as Radiator core materials |
|
Density
g/cm³ |
Thermal
Conductivity
(w/m°C) |
Tensile
Strength
(MPa) |
| |
| Cu
fin |
8.95 |
377 |
330 |
| Br
tube |
8.53 |
120 |
435 |
| Al
fin |
2.75 |
222 |
40 |
| Al
tube |
2.75 |
160 |
145 |
Secondly,
aluminum has better conductivity than brass, but radiator tube strength
is equally, if not more, important in a street application. Brass, of
course, is considerably stronger than aluminum. This overall strength
allows for thinner walled tubes which more than compensate for the difference
in conductivity.
Taking
advantage of these characteristics – superior thermal conductivity,
strength and corrosion resistance – manufacturers can use thinner
material throughout and thereby design a copper/brass radiator having
a lower total weight than one made from aluminum, but with the same or
better heat rejection capacity.
|
 |
| The
Modine unit is a direct drop-in, requiring no modifications
to the stock brackets. |
Installation
1. Drain the radiator (while cold!) and dispose of the old coolant
properly.
2. Using an 11mm wrench, remove the four bolts holding the fan to
the water pump pulley. Gently rest the fan in the shroud.
3. Use the same wrench to unbolt the two bolts at the top of the shroud
and carefully remove the shroud with the loose fan. Be sure to pull
the coolant recovery tube off of the radiator (this will be replaced
with a new tube provided with the new unit.) The coolant recovery
tank stays on the shroud.
4. Using a set of Channel Lock pliers remove the clamps on the upper
and lower radiator hoses and pull the hoses off of the old radiator.
This is a good time to inspect and replace worn hoses. The clamps
should be replaced with worm gear style clamps.
5. Using a ½" flare tubing wrench, carefully disconnect
the transmission cooling lines (if needed). The fittings will also
need to be pulled off of the old radiator and installed with Teflon
tape on the new one.
6. Now the radiator is ready to come out. Using a 10mm wrench, remove
the two top hold down clamps and carefully lift out the radiator.
7. Remove the two nut clips from the top of the old unit and transfer
them to the new one. Repeat this with the two lower clips for the
shroud.
8. Clean the rubber mounting pads before installing the new unit.
These will need to be trimmed if you use the large three-core "Max
Cool" radiator.
9. Carefully slide the new radiator into place and reinstall the top
clamps.
10. Reconnect the transmission cooling lines, if needed (you did swap
the fittings, right?)
11. Reconnect the hoses with new clamps.
12. Make sure you replaced the coolant tube on the coolant tank. I
used a large tie wrap to secure it as it will not see any high pressure.
13. Carefully slide the shroud and fan onto the mounting clips at
the bottom of the radiator (you swapped those too, right?)
14. Replace the two mounting bolts in the shroud.
15. Reinstall the fan.
16. Make sure the coolant recovery tube is reattached to the radiator.
17. Install a new radiator cap! Be sure it is the right relief pressure
for your application- in this case 16psi.
18. Run to the store pick up some fresh antifreeze and refill your
shiny new cooler with the proper mixture- 50/50 water to AF in very
cold climates, 70/30 water to AF in very hot climates. Check for leaks.
19. Start the car and run while parked until operating temperature
is reached, checking for leaks continuously.
20. Shut the car off and let it cool down and then check your coolant
level- add as necessary.
21. Run the car in idle until warm again and check transmission fluid
level if you have an automatic.
22. Go for a short drive and check for leaks some more! |
|
The
2" thick core of the GDI radiator required slight modification
of the brackets for our Flex-a-Lite fan and overflow bottle. However
there were no clearance problems between the fan and waterpump pulley.
With a thicker fan, such as the Lincoln Mark VII units, there could
be some additional modification and trimming required.
|
|
|
Results
As expected the new, three-core, radiators significantly dropped the engine
coolant temperatures on both our '88 and '92 LX Mustangs. The '88 Mustang,
which has the larger GDI radiator, electric fan, and is a five-speed,
now runs at a constant 180-190°, regardless of whether the car is
in stop and go traffic or on the freeway at 75mph. On several triple-digit
days we've had the AC on max while stuck in 5 mph bumper-to-bumper hell,
and the gauge never moved beyond 190° (between the A and L on the
stock gauge.)
Our '92 LX, with the slightly smaller Modine radiator and the automatic
transmission, also runs considerably cooler. However in similar heat and
traffic, with the AC running, the author has observed the stock gauge
creep up towards the "O" on the scale. We figure part of this
is due to the stock clutch fan not moving enough air at idle.
The bottom line is that a new three-core radiator will make a noticeable
difference in reducing the engine coolant temperatures. The best bet,
if you are willing to make a few modifications to the brackets, is the
GDI "Max Cool" 433138 radiator. For a direct bolt-in, with a
relatively stock engine, the Modine three-core is a very easy to install
radiator that yield's good results. F/M
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