Avoid Carnage! How to Inspect Your 2009-2017 Ford F-150 6R80, 10R80 Transmission Cooler Lines

The transmission cooler lines on pre-2018 Ford F-150 pickups have a tendency to corrode, which can lead to expensive repairs if neglected.

As many modern Ford F-150 owners are already well aware, the 6R80 and 10R80 transmissions used in those pickups have their fair share of known issues, ranging from shuddering to harsh/delayed shifts, and slipping, to name just a few. However, there is another potential killer when it comes to these gearboxes as well – the transmission cooler lines, which can fail and ultimately lead to a complete and costly transmission failure as well.

In this video from Brian Makuloco of the Ford Tech Makuloco YouTube channel, our resident technician and Blue Oval expert touches on how, exactly, one can inspect the transmission cooler lines in their Ford F-150 pickups to potentially prevent this from happening. This is a common issue with the 2009-2017 Ford F-150 and both the 6R80 and 10R80 gearboxes used in those models, and with winter quickly approaching, now is the time to replace that part if it is indeed faulty.

Here, we get a good look at how the transmission cooler works on the 6R80, including a peek at the nipples of that unit, which tend to corrode. However, the heads on the lines also tend to pop off, which is the most common problem. There’s a thin crimp along with a thicker piece supporting the quick connects, locks, and o-rings, with the root cause of the problem coming from fatigue that can occur over time between those two pieces.

Eventually, the top piece will simply become detached, resulting in fluid being dumped all over the road – which can empty the transmission quickly and lead to a rapid failure of that unit. To prevent that from happening, one can simply crawl underneath their Ford F-150 and locate the line set on the driver’s side of the transmission, and then follow it forward to the rubber hose section near the front of the vehicle.

There, it’s pretty easy to inspect the heads, which are the common failure point here, and in this case, that piece has popped right off. Makuloco says to just “yank” on those lines to check and see if the heads are about to pop off anyway, as it can be difficult to tell if that’s the case by simply looking at them. On EcoBoost models, it’s also quite common for those heads to become corroded as well.

As for later models with the 6R80 transmission and 10R80 up to the 2017 model year – 2018 pickups introduced an improved design that eliminated this particular problem – that design is a bit different, though the problem remains the same. Those pre-2018 pickups have a cooler warmer block that the lines run into (shown above), but it faces forward, subjecting it to rain, snow, salt, and all kinds of nasty stuff that can lead to corrosion, as is the case here.

That rot is pretty easy to spot, and in this case, leads to smaller leaks, though bigger ones occur as things get worse. Thus, if your Ford F-150 shows these signs of premature transmission cooler line failure, it’s best to get ahead of things and replace them before you have to shell out big bucks for a new transmission.

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Brett Foote

Brett Foote has been covering the automotive industry for over five years and is a longtime contributor to Internet Brands’ Auto Group sites, including Chevrolet Forum, Rennlist, and Ford Truck Enthusiasts, among other popular sites.

He has been an automotive enthusiast since the day he came into this world and rode home from the hospital in a first-gen Mustang, and he's been wrenching on them nearly as long.

In addition to his expertise writing about cars, trucks, motorcycles, and every other type of automobile, Brett had spent several years running parts for local auto dealerships.

You can follow along with his builds and various automotive shenanigans on Instagram: @bfoote.