Installing Strictly Diesel’s 6.7L Ford Transmission Cooler

In 2011, Ford released their all-new, in-house developed and built 6.7L Power Stroke engine platform paired with the 6R140 transmission. To say it’s been a homerun, when compared the earlier 6.4L and 6.0L Power Strokes would be an understatement, but that doesn’t mean that Ford got it completely perfect. While the durability and longevity of the 6.7L and that 6-speed transmission has been much improved over its predecessor’s, there are still a few things that the aftermarket has developed that can be a worthwhile investment.

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The 2011-2019 6.7L Power Stroke uses a liquid to liquid transmission cooler tucked up behind the bumper that can lead to extreme fluid temperatures while towing. Strictly Diesel developed their complete liquid to air cooler to aid in temperature control and eliminate those common 220+ degree temps owners see.
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With the included step-by-step instructions, and some excellent color photos, the new transmission cooler kit can be installed by an average mechanic in about three hours. It’s a simple, straight forward, installation but it will require some cutting and modification to the grille shell and grille support.

Case in point, the cooling systems under the hood of that 2011-2019 Ford truck. Ford got away from running the standard air-to-air intercooler for the turbocharger system and developed a liquid-to-air cooler as it offered more consistent charge temperatures. They also converted their transmission cooler from the usual big liquid-to-air mounted behind the bumper, to a much smaller liquid-to-liquid cooler that resembled and engine oil cooler. While we can’t say for sure Ford’s reasoning for this, anyone that owns the 6.7L Power Stroke and uses it for heavy towing, will confirm the staggering transmission temperatures they’ll see under load. In the summer months, while towing heavy in a 2011+ Power Stroke, it’s not uncommon to see 240-degree fluid temperatures through that transmission. While Ford suggest this is normal, anyone in the industry will attest to fluid breakdown and heat being the #1 killer for transmission longevity.

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Using an OE style 30”x7” cooler, the supplied pre-bent stainless steel brackets need to be bolted on using the supplied hardware, which include captured thread nuts to make this a super simple install, with an OE finished look.

Looking to overcome issues with hot fluid temperatures and extend transmission fluid life and overall durability, Strictly Diesel, a big name in repair and performance work out of Phoenix, AZ, went to the drawing boards to develop something that could easily install and help bring those temperatures down. With extensive research and abusive testing regiments with their F450, they came up with the perfect air-to-liquid cooler kit for the 2011-2016 and 2017-2019 Ford applications.

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With the brackets assembled on the new cooler, it’s time to start the disassembly process on the truck. While Strictly Diesel offers a kit for the 2011-2016 Ford trucks, we’ll be installing their 2017-2019 version on this 2018 F250.
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With the factory grille shell removed, and the horn un-bolted from the center grille support, it’s time to cutaway the center support bar using the supplied cable saw. The reinforced fiberglass plastic support will cut easily if you follow the instructions and make long, slow pulls on the saw.

In their initial data collection and testing process, towing an 18,000-lb 48’ triple-axle enclosed trailer with living quarters and their 10-second Power Stroke drag truck they recorded average freeway speed temperatures of 240-degrees. Average unloaded temperatures hovered at 210-degrees, which is still abnormally high compared to other diesel pick-up truck and automatic transmission combinations out there. After finding the perfect cooler and engineering some simple bracketry, the addition of this transmission cooler kit made immediate and effective changes in overall fluid temperatures, netting a maximum of 220-degree temperatures towing once installed.

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With both the upper and lower cuts completed, the center support can be pulled out and discarded. It’s a good idea to go over your cut lines to make sure everything is smooth and there are no points that will interfere with the soon to be installed transmission cooler.
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Using the supplied cable ties, you can loop them around the ends of the trans cooler brackets and the upper condenser line to help with positioning of the cooler before drilling the new mounting holes in the out support. The ties can be removed once it’s permanently secured.

This system retains the factory transmission cooler but adds the large air heat exchanger directly behind the grille where it can get maximum airflow through the core to help reduce fluid temperatures over the capacity of the stock unit. Adding this cooler takes only a couple hours and will increase fluid capacity by 1-1.5 quarts. In our test vehicle, a 2018 F250 running a mild lift and larger tires, it was common to see 230-degree temperatures towing in the summer and on the morning of our install peaked at 210-degrees with just a 14-foot flatbed trailer and side by side in tow. After installation of the Driven Diesel cooler kit, making the same drive back home with the same load, our fluid temperatures peaked at just 172-degrees with outdoor ambient temperatures at 40-degrees. The addition of the cooler will require some minor cutting to the grille support, but nothing that can’t be tackled by the average mechanic. If your 6.7L Power Stroke is used for heavy towing, this modification is one we’d definitely add to the list of must haves.

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Using a 7/64 drill bit, the plastic support can be drilled out in the three screw locations on either side of the cooler. Be sure to check the cooler for center and that it’s level on the truck. You’ll also want to make sure it’s positioned where it won’t contact or rub anywhere.
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Once positioned and drilled, the supplied screws can be inserted to hold the cooler permanently in place. Use caution here, as the screws are threading into a reinforced plastic, it’s suggested to only use a screwdriver here, as a power drill or impact could overtighten and strip the material easily.
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With the cooler mounted, it’s time to tap into the factory cooler lines located under the truck directly behind the bumper. Using a miniature tube cutter, you can cut the middle section of the driver side cooler line. You’ll be making two cuts to this line to make room for the supplied fittings.
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Strictly Diesel uses a top quality fitting to attach the new rubber hose to the factory hard line. The ferrule inside the fitting will tightly seal the hardline for a leak free connection when installed per the instructions.
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The barbed fittings will bottom out on the hardline and allow you to tighten the end cap nut until it’s snug allowing for a trouble free seal. Once installed, and the supplied rubber hose is attached and clamped, the lines can be clipped back into their factory location.
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The supplied hose has a 400-psi rating and will route easily up past the bumper brackets to the inlet and outlet ports on the new transmission cooler. Supplied hose clamps and brackets will allow you to secure the hoses to the truck, so there will be no concerns of them rubbing or leaking.
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With our transmission cooler installation complete, it’s time to add a little fluid to the transmission and check the system for leaks before making our final modifications to the grille and installing it back on the truck. You can also see the relocation of the factory horn assembly here which was easy using supplied hardware.
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Before finishing up our install, this scoop must be cut off the factory grille valance, which was done easily with a small saw blade. The backside of the grille shell will also need to be trimmed in a few places to allow proper clearance around the newly installed transmission lines.
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All back together and looking like a factory equipment, you can see the new Strictly Diesel transmission cooler peaking from behind the grille. This liquid to air cooler will get great airflow across the core here and has been tested to show consistent 30-40 degree temperature drops under load.
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They say the proof is in the pudding and it’s hard to deny results like that. While towing through stop and go traffic, we recorded 210-degree fluid temperatures the morning of our cooler install. Making the trip back home in the exact same conditions, our transmission fluid ran just 172-degrees. We can’t to test this thing out in the summer heat towing 15,000lbs.

Sources:

Strictly Diesel
www.strictlydiesel.com

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