OPERATION OLD SCHOOL TOW RIG: PART 4

Heavy Duty Transmission Cooler and Deep Pan Install

Following the installation of a new Class V hitch, trailer brake controller, and free-flowing exhaust system in Part Three, this time we’re replacing another vital component in our ’97 F-350’s towing equation: the transmission cooler. Amazingly, Ford used the same tiny transmission cooler on its Broncos as it did on its 1-tons—and our truck was still sporting it. Running around empty, we had no complaints. But hook a small trailer behind it and 200-degree temps were soon to follow. For a truck that would soon be regularly saddled with 10,000 to 12,000 pounds, there was no way we were sticking it out any longer with the inferior factory cooler.

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After pulling the grille and looking things over, we quickly realized that it made the most sense to pull the radiator and mount the Mishimoto transmission cooler behind the A/C condenser. With a game plan established, Jake Bosie of Flynn’s Shop got started by draining the engine coolant.

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While the coolant drained, the truck was raised via two-post lift and Bosie got started with the transmission service and Goerend pan install. Once enough transmission fluid had been drained to remove the original pan, Bosie pulled it, removed the E4OD’s filter, and began cleaning up the pan’s mounting surface with a die grinder and Scotch-Brite pad.

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With the old sealing ring removed and the new one in place, a fresh Ford transmission filter (PN YC3Z-7A098-BA) was installed. Then Bosie transferred our transmission temperature sensor from the old pan into the new Goerend unit.

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Made from lightweight cast aluminum for optimum heat dissipation and durability, the Goerend E4OD/4R100 transmission pan offers the same key features that made the 47/48RE and 68RFE pans a hit with the Dodge crowd. A sloped floor design provides for 100-percent drainage, and the magnetic drain plug (with a copper sealing ring) requires a 1-inch socket for removal, greatly simplifying service. Another obvious selling point is that the pan adds approximately 4.5 quarts of fluid capacity.

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Goerend supplies a high-quality Duraprene gasket with its transmission pan. Unlike some competing products (where you’re better off sealing the pan with RTV), this pan gasket won’t crack once you tighten up your pan bolts.

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Once all coolant had been drained, Bosie detached the transmission supply and return lines and radiator hoses from the radiator. Then the engine fan was broken free and (along with the fan shroud) removed.

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Holding the gasket in place on the pan using one of the Allen bolts supplied by Goerend, Bosie began threading each pan bolt into the transmission case. He would eventually torque all 20 Allen bolts to 15 ft-lb.

For old body style Ford and ’99-03 Super Duty owners alike, ditching the factory transmission cooler in favor of one from a 6.0L application is extremely popular and highly effective. However, we decided to take things a step further by installing Mishimoto’s 37-row 6.0L cooler—an upgrade over the factory 6.0L unit in every way. To shoehorn the heavy duty transmission cooler into our old Ford, we once again enlisted the help of Flynn’s Shop in Alexander, Illinois. During the install we also treated the E4OD to a new filter, 14 quarts of fresh fluid, and a high capacity pan from Goerend Transmission.

Thanks to the addition of the massive Mishimoto transmission cooler, our old body style Ford’s transmission is running 30-45 degrees cooler than it used to, and the truck itself is more trailer-ready than it’s ever been. Tune in next month for the final installment, where we’ll be upgrading to an electric fuel delivery system for improved supply pressure and volume, added reliability, and more power.

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Next, the radiator mounting brackets located near the top on each side of the radiator were removed, followed by disconnecting the coolant line that tees into the heater core hose. From there, the radiator was easily lifted up and out of the engine bay.

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Just as we’d hoped, pulling the radiator and engine fan gave Bosie all the working space he needed. With enough room present in the radiator core support to move the radiator back toward the engine yet still clear the fan, the space between the A/C condenser and radiator was the perfect spot to install the Mishimoto 6.0L cooler.

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Designed as a bolt-in replacement unit for the ’03-07 Super Duty, Mishimoto’s 37-row, stacked-plate 6.0L transmission cooler (PN MMTC-F2D-03SL) offers a 21-percent increase in core volume over the 5R110 TorqShift’s factory 31-row cooler (the cooler that was available on trucks spec’d with Ford’s factory tow package), and provides a 10+ degree drop in fluid temperature. Its 34 x 1.34 x 23.5-inch overall size (L x W x H) absolutely dwarfs the factory ’97 F-350 cooler and also features a larger ½-inch inlet and outlet.

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After mocking up the transmission cooler with some makeshift brackets, Bosie found that the mounting tabs welded to the sides of the Mishimoto cooler wouldn’t clear the core support. For proper clearance, both mounting tabs were cut down by roughly an inch.

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Because the original mounting holes were now gone, Bosie drilled two new ones (one per side) in the cooler’s side-mounting tabs. He then cut down the previously employed 1/8-inch makeshift brackets to their final length of 16 inches and attached them to the transmission cooler via 10mm bolts, lock washers and nuts.

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The other end of the aforementioned 1/8-inch steel cooler-to-core support bracket effectively attaches the transmission cooler to the top of the radiator core support. Later, when the cooler was lowered into position for the final time, the top of each bracket was fastened to the upper horizontal section of the core support via two 8mm self-tapping screws (shown).

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To add some breathing room between the transmission cooler and radiator, Bosie fabricated two 5/16-inch steel brackets approximately 1 inch wide and 6 inches long. By installing them between the core support and the radiator frame, they act as spacers that effectively relocate the radiator 5/16 inch closer to the engine. We’ll note that longer radiator frame bolts with 13mm heads had to be employed with the spacers in the mix.

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As for the lower mounting tabs on the Mishimoto transmission cooler, they too would have to be tweaked in order to work. Bosie determined that if the mounting legs were angled slightly downward they could be made perfectly flush with the truck’s core support in conjunction with using the supplied rubber bushings.

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Once the lower mounting tabs of the transmission cooler had been bent, the upper cooler brackets were tightened up. Then Bosie carefully lowered the radiator into its new position and set about securing it via the factory radiator mounting brackets and hardware.

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With the radiator in place, the transmission supply and return lines were reattached and the rusted original constant tension clamps were replaced with new worm gear clamps. Then Bosie reconnected the heater core line and the lower and upper radiator hoses, and then reinstalled the engine fan and shroud.

There was no way we were sticking it out any longer with the inferior factory
cooler.

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Attaching the lower mounting tabs to the bottom of the radiator core support called for two ¼-inch holes to be drilled. From there, the supplied rubber bushings and ¼-inch bolts from Mishimoto were installed and tightened up.

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Because the original transmission cooler lines were 5/16-inch diameter and the inlet and outlet of the Mishimoto cooler are ½-inch, reducer fittings were in store for us. These ½-inch x 5/16-inch stainless steel barb fittings came from Dorsey Diesel, a company that specializes in building tow- and competition-ready E4OD/4R100 transmissions.

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Sourcing several feet of ½-inch hose locally, Bosie cut two hoses to length, pressed one end onto the Mishimoto transmission cooler’s inlet, and then tied it into the ½-inch x 5/16-inch barb fitting he’d just installed. The process was repeated on the transmission cooler outlet side.

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After cutting both the truck’s existing supply and return transmission cooler lines, the 5/16-inch ends of the barbed fittings were pressed in. Then each line’s worm gear clamp was tightened up for added insurance.

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To avoid any sharp bends in the ½-inch rubber transmission hoses we opted to route them outside of the core support, en route to where they meet the 5/16-inch lines on the passenger side of the truck. In areas where the hoses rest on the edge of the core support (where rubbing due to vibration might become an issue), Bosie wrapped a larger section of hose around the line and zip-tied it in place.

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This is something we should’ve done a long time ago: place the stock transmission cooler on the scrap pile. It’s amazing that this same undersized heat exchanger was shared between the Bronco and the F-350—one vehicle with a 7,000-pound towing capacity and the other rated to tow as much as 13,900.

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Once Bosie had looked over his work and double-checked that everything was tight, he started refilling the engine with coolant. The coolant would be completely topped off the next day, after all air had been purged from the system.

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Topping off the transmission’s fluid level called for 14 quarts of ATF thanks to the added capacity of the Goerend pan. Not looking to reinvent the wheel, we stuck with Mercon V from Motorcraft—the same fluid we’ve been running in our John Wood Automotive E4OD for seven years.

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For a refreshed look up front, we ditched our aging grille for a chrome replacement from Complete Performance. We’ll note that because our F-350’s headlight panel had been reworked during the installation of the intercooler, some cutting on the backside of the new grille was required to make it fit.

First Impressions

As we mentioned, in 6.0L applications the Mishimoto cooler is known to drop transmission fluid temps by approximately 10 degrees. Considering we’d just installed a cooler roughly 10 times the size of the truck’s factory unit, we expected to see a much larger drop in ATF temperature. Our expectations were confirmed when we took the truck for its first test drive on a 90-degree day—where highway driving, stop-and-go traffic, and idling were all part of the test loop. Before the transmission cooler had been installed, we could easily see our transmission temp gauge read 100 degrees above ambient (the general rule of thumb for transmission operating temperature), but it didn’t take long to crest 200 degrees with a small trailer in tow on a 90-degree day. With the Mishimoto cooler in the mix, we’ve yet to see this same gauge read higher than 165 degrees under any circumstance. Across the board (in all driving conditions) the truck’s transmission runs 30 to 45 degrees cooler than it used to.

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SOURCES

Complete Performance
409.383.4766
CPAddict.com

Dorsey Diesel
573.701.2623

Flynn’s Shop
217.478.3811

Goerend Transmission
563.778.2719
Goerend.com

Mishimoto
877.466.4744
Mishimoto.com