B&M offers two distinctly different designs of coolers for engine oil and transmission fluid. The stacked-plate cooler, seen in the cutaway, is extremely durable and great for high-speed driving. The Hi-Tek cooler, outfitted with an electric fan, offers superior cooling at low speeds when ambient airflow is unavailable.
Long transmission life is basically dependent on one thing: heat dissipation. Too much heat will kill any transmission, no matter how good the internal parts may be. Whether you're mudding, crawling, playing in the sand, or towing your toy, your automatic is creating friction and heat and is relying on the transmission fluid as a source of coolant and lubrication.
Although most every modern vehicle employs a radiator-based cooling tank for automatic transmission fluid, this is rarely adequate for the rigors of fun in the dirt. In some instances, an auxiliary fluid cooler may be standard equipment, but this is by no means the end of the line when it comes to cooling.
We want to show you how far the technology of cooling has come. To illustrate this, we gave the transmission experts at B&M Racing & Performance Products a ring. According to the VP of engineering at B&M, "Fin-and-tube coolers only scratch the surface of cooling technology. Fin-and-plate and stacked-plate coolers have shown a 25- to 30-percent increase in efficiency while creating 15 times less flow restriction."
So what are the differences in cooler designs? First, let's look at the most traditional type of cooler, the fin-and-tube cooler. This type of cooler uses a single tube to move the fluid from one end of the cooler to the other. The fluid is cooled by the air traveling over the small fins running top to bottom, much like a radiator. Although this cooler design does help remove heat, it has the least amount of surface area in contact with the fluid.
The most compact cooler design of all is the stacked-plate model. This design can be likened to a honeycomb that allows oil to travel from one end to the other while air travels over the surface. In addition to being very efficient for its size and weight, the stacked-plate cooler is extremely durable, thus it is great for trucks that will see debris at high speeds such as stadium race trucks or prerunner-type vehicles.
The third and most efficient type of cooler is the fin-and-plate-style cooler, which uses small hollow plates to move the fluid from one side of the cooler to the other. This style of cooler allows more fluid to be exposed to the plates, thus improving cooling efficiency. Similar to the fin-and-tube cooler, the fin-and-plate cooler also uses vertical fins to catch ambient air to remove heat. This design allows the oil to move freely inside the cooler, keeping restriction to a minimum. This is also the only type of cooler available from B&M offering the Hi-Tek electric fan system.
Our donor vehicle was an '03 Expedition 4x4, basically stock aside from larger wheels and tires and a 2-inch lift kit. Used mainly for the occasional trip to the river and pulling a Jeep to Moab, keeping the tranny cool was a must. Our weapon of choice: a B&M Hi-Tek fin-and-plate cooler sporting a 12V suction fan and built-in thermostatic fan control for more consistent operating temperatures. Although our Expedition had a small fin-and-plate cooler, the upgrade was necessary for the long-term survival of our stock transmission when towing. Having an OE cooler made the install simple - all of the lines were pre-existing and ready to be connected to the new, 50-percent-larger Hi-Tek cooler.
To access the OE cooler, we removed the factory front bumper and bumper cover. | 
The stock cooler was held in place with three bolts connected to the core support and utilized integral brackets. | 
We drained the fluid from the cooler and removed it. |
The upper grille mount was removed and marked for trimming. The entire area in white was removed with a Dremel for fitment of the larger cooler. | 
The stock cooler lines were 1/2-inch NPT (male), a perfect fit for our new cooler. We made no changes to the line lengths or the fittings. | 
After our trial fitment, we removed the cooler and trimmed 3/16 inch from the plastic grille support to make room for our new cooler straps. |
The new Hi-Tek cooler had four built-in mounting locations: two on the top and two on the bottom. Our old cooler was mounted from the sides. This meant a new method of attachment would have to be devised. We made C-shaped galvanized-steel brackets to hold the bottom of the cooler. | 
To keep the top in place, we used galvanized-steel straps. We Kryloned them black just for chuckles. | 
With the cooler in place, we began wiring our electric fan and switch. We pulled a 12V electrical source from an unused diagnostic plug located right behind the passenger headlamp. We used our core support as a ground. The switch can be activated by completing 12 volts or completing a ground. The wiring for the switch was black, so for simplicity we made the switch a ground. |
The B&M Hi-Tek cooler is almost 50-percent larger than the stock unit. | 
With everything in place, we added about 1 quart of B&M Trick Shift to bring the fluid level back to the top. | |