
Negotiating rocky desert trails such as this one in low range requires keeping the engine and transmission cool and sometimes a mechanical fan just isn�t enough.
Living and wheeling in Arizona requires an engine that runs cool, because the air temperature usually isn�t. While we don�t wheel in triple-digit temperatures�usually, that is�we do four-wheel in the 80s and 90s so it behooves us to try everything we can to keep our engine and transmission temps under control.
With this is mind, when Precision Auto in Kingman installed the Chevy 350 V8 and GM TH350 automatic transmission in my �82 CJ7, they separated the tranny cooling from the radiator with its own trans-cooler and installed a large mechanical fan on the water pump pulley. Precision also installed the largest aluminum radiator I could afford, even though it wasn�t a cross-flow (which is a more efficient design), and I hit the trails just out of town.
To fill in its background, perhaps now is a good time to give a brief outline of the 30-year-old CJ7. In addition to the GM engine and transmission the Jeep has a set of Advance Adapters exhaust headers, a Dana 300 transfer case with a TerraFlex 4:1 low range, OEM differentials with 4.56:1 gears and ARB lockers (Dana 30 front end has RCV axles; AMC 20 rear end has Warn full-floating axles), Superwinch free-wheeling hubs, Skyjacker 4-inch lift, Goodyear 12.50x15x35 MT/R with Kevlar tires, Alcoa aluminum wheels, Ramsey winch, VDO gauges, and Bestop seats and luggage rack.

First step is to disconnect the fan; remove the negative cable first, then the positive cable.

Maradyne (http://www.maradynehp.com/) recently introduced the Mach Two model high-performance dual 16-inch fans. When I saw this product I thought it would work great for my Jeep. The Mach Two fans are available in three sizes as of this writing.

As you can see, there are several inches between the engine fan and the radiator. Without a shroud to concentrate the fan�s air movement, quite a bit of airflow is lost. I could have spent a lot of money having a custom shroud built, but the Maradyne fans do the job more efficiently and I gain a few horses by losing the mechanical fan.

In order to slip the Maradyne fans into place with their housing, I had to disconnect the upper (return) hose from the radiator.

Paul Schupp of Precision Auto in Kingman, Arizona, is installing an upper mounting bracket for the fan housing. Due to the install being in a Jeep, we wanted more support than might be needed for a street-only car, so we used a piece of aluminum angle that spanned the radiator.

With the aluminum angle bolted into place, I slipped the dual fan housing into place between the engine and the radiator.

First I bolted the housing to the aluminum with self-tapping screws.

Then I inserted as many self-tapping screws along the driver�s side of the radiator housing.

Using a 90-degree angled drill motor�to clear the alternator�I inserted several self-tapping screws down the passenger�s side of the housing.

Maradyne uses universal wiring diagrams and universal wiring looms for the installation. This diagram is for non-air conditioned vehicles, which is the one I used for the 1982 CJ7.

This particular wiring loom uses a probe in the radiator for temperature sensing. It is placed as near as possible to the inlet hose from the engine and out of direct air flow (if possible). Note the transmission cooler that�s also used on this Jeep to maintain temperature control.

The MFA100 wire harness�which came with my fan kit�includes an adjustable thermostat that is connected to the remote sensing bulb (probe). The thermostat may be adjusted to engage at any temperature between 32°F and 248°F. I used self-tapping screws to mount it using its included mounting bracket.

Here are some of the tools you�ll need for the install: pliers, wire crimping/stripping tool, 12VDC circuit tester, and miscellaneous solder-less connectors.

At the time of installation, Maradyne did not include a wire harness for dual fans�just for a single fan setup�and its fan connector was not a �T� connector matching the fans� T-connectors, they were two separate connectors. For this reason�although the single set of fan wires matched the color code (blue and black) � I verified the blue wire is for positive and the black wire is for ground by running jumper wires from the battery (this causes the fan to blow in the correct direction). I connected the black ground wire to the aluminum mounting bracket.

You�ll need the pliers to use this solder-less connector to attach the positive wire from the second fan to the positive wire for the first fan.

I used plastic tie wraps to secure the fans� wiring up and out of the way.

Maradyne�s cool design includes over-pressure relief flaps such as these along the top and bottom of the housing so that air can bypass the fans at highway speeds, so that air keeps flowing in all types of conditions.

With the fans mounted and connected to the wire harness, it�s time to connect the harness to the Jeep�s wiring. Use the 12VDC circuit tester to find a circuit that becomes �hot� when the ignition is on. This is to control the fan system�s relay to provide power for the fans only when the ignition key is on.

Route the 10-gauge power supply wire�with its inline 35-amp fuse�to the positive side of the battery. Since there are two fans I needed to replace the 35-amp fuse with a 40-amp fuse to provide sufficient power to the two 225-watt fan motors, which could draw a maximum of 35.8 amps with a total airflow of up to 4,320 CFM.

My Chevy 350 engine�s thermostat is set at 180°F and it used to run at 210°F to 220°F during the warmer months with the mechanical fan.

Using a thin-bladed screwdriver, adjust the fans� thermostat to kick them on at a temperature slightly above 180°F and to shut off at 180°F. (I also attached the black ground wire to the Jeep with a self-tapping screw.)

To prove the security and strength of the fan installation, I competed in a mud bog. The fans worked perfectly!

I can now negotiate the trails of northwestern Arizona without worrying about overheating.