6R140 Transmission Cooler 2017-2022

Seeing ATF on the frame rail of a 2017-2022 Ford Super Duty, or a puddle under the transmission that keeps coming back after you wipe it down? On the 6R140 trucks from this body style, the steel cooler tubes with their rubber hose sections are a common source. This listing, titled as a transmission cooler, is actually the complete cooler line assembly: the inlet and outlet (pressure and return) lines that run between the 6R140 and the cooler, sold new as Dorman part 724-603. It does not include the cooler core itself.

What the cooler lines do in a 6R140

The 6R140 sends hot fluid out of the torque converter circuit to the cooler and brings it back to the case to lubricate the gear train. Every bit of heat from towing, a long grade or a slipping converter clutch leaves through these two lines. At the transmission end the tubes push into ports in the case and are clamped down by a bolted hold-down plate, not threaded fittings. Along the run, the formed steel tube changes to rubber hose sections that take engine movement. Those rubber sections age from heat and road debris, and the steel can rust or chafe where it is clipped to the truck. GEARS magazine lists 195 to 230 degrees F as the normal operating range for this transmission, and lines that leak or kink let it run hotter and lower on fluid.

Symptoms of a failing cooler line

• ATF wet spots at the case-side hold-down plate, along the frame rail or near the cooler connections
• Fluid level that drops between checks with no other symptom
• Cracked, swollen or chafed rubber sections, or rust scaling on the steel tube
• Higher transmission temperature on the gauge when towing, after the cooler and coolant system check out
• Burnt ATF smell after a hard pull, with fresh fluid on the lines underneath

How to confirm it is the lines

Clean the area, run the truck to full temperature and look for where fresh fluid first appears. Ford Special Service Message 46198 covers some 2017 Super Duty 6.7L trucks built on or before November 3, 2016 that leaked at the cooler tubes because the tubes were not fully seated or the hold-down plate was misaligned. In that case the fix is reseating the tubes and a new plate bolt, not new lines. Our 6R140 cooler line replacement guide walks through both ends and the bulletin procedure. If the truck overheats without a leak, the cause may be inside the transmission; the 6R140 pump failure guide covers low converter charge and cooler flow.

Fitment

The application list for this assembly covers the Ford 6R140 six-speed automatic in 2017, 2018 and 2019 F-250, F-350, F-450 and F-550 Super Duty, plus the 2020 and 2022 F-350 Super Duty. Model year 2021 is not on the list, and the F-250 is only listed through 2019, so do not assume those trucks match. From 2020 on, the 6R140 in the Super Duty was paired with the 6.2L gas V8, while the diesel and the 7.3L moved to a 10-speed. Line routing can differ by engine, cab, bed and cooler package, so compare the bends and end fittings with the photo and your old lines, or send us your year and VIN to check before ordering. It will not fit 2011-2016 trucks. See everything for this unit on the 6R140 parts page.

Install notes

• Lower the fluid level first by draining the pan; opening the lines on a full system will dump fluid.
• Release the quick-connect ends at the cooler with the correct disconnect tool instead of prying.
• At the case, make sure each tube is fully inserted and square in its port before the hold-down plate goes on. Ford's bulletin uses a new bolt, W715131-S437, with washer W718565-S437U, torqued to 25 Nm (18 lb-ft).
• Clip the new lines into the factory brackets so they cannot rub on the frame or exhaust.
• Refill with MERCON LV, check for leaks, and set the level with the fluid hot.

If the truck ran low on fluid before you caught the leak, change the filter and fluid while you are under it. Sonnax documents that wear in the line pressure control valve bore can reduce cooler and converter flow, so if temperatures stay high with new lines, have the valve body checked; the 6R140 valve body zip kit is our valve body refresh option. A noisy or weak 6R140 pump is the other part to rule out when temperatures stay high.

Is this the transmission cooler or the lines?

It is the cooler line assembly, the inlet and outlet lines between the transmission and the cooler. The cooler core is not included.

Will it fit my 2021 F-250?

Model year 2021 is not on the application list for this assembly, and the F-250 is listed only for 2017-2019. Send us your VIN and we will check before you order.

Does it fit a 2011-2016 Super Duty?

No. The earlier trucks use a different line assembly. Look at our 6R140 parts page for the earlier cooler line options.

My 2017 leaks at the transmission end. Do I need new lines?

Maybe not. Ford Special Service Message 46198 covers early-build 2017 6.7L trucks leaking from misaligned tubes or hold-down plates. Reseating the tubes and installing a new plate bolt torqued to 25 Nm may fix it.

What fluid do I add after replacing the lines?

Ford specifies MERCON LV for the 6R140. Top off through the fill and set the level with the transmission hot.

Is a relearn needed after replacing cooler lines?

No. Lines do not affect shift adaptives. Just make sure the fluid level is correct and check both ends for leaks after a drive.

• 6R140 Cooler Line Replacement Guide
• 6R140 Pump Failure Symptoms and Replacement
• Ford 6R140 TorqShift Problems and Service: A Rebuilder's Guide
• 6R140 Pressure Control (EPC) Solenoid Symptoms