ZF8HP Transmission Cooler 2016

If your 2016 Ram 1500 with the eight-speed automatic is dripping red fluid near the front of the truck, has a cooler core damaged by road debris, or has cooler lines that are rusted or kinked, this is the factory part that fixes it without guessing at aftermarket plumbing. It is a used, original-equipment transmission oil cooler removed from a 2016 Ram 1500 with the ZF-designed 8-speed, and it comes with its attached lines, so the connections that most often weep come as one assembly.

What the transmission cooler does on a Ram 1500 8-speed

Every shift in the 8-speed is a controlled clutch slip, and torque converter slip at low speed adds more heat. That heat goes into the fluid, and the cooler is where it leaves. Fluid leaves the transmission, flows through the lines to the cooler mounted up front in the airflow, gives up heat and returns to the case. Ram's 2016 user guide warns owners that a winter front must leave part of the grille open so air reaches the automatic transmission oil cooler, which tells you how much the truck depends on it. When a cooler leaks, the transmission loses fluid; when it is blocked or starved of air, fluid runs hot and wears out faster.

Signs the cooler or its lines need replacing

• Wet, red fluid on the cooler, its line fittings or the frame below them, or spots under the front of the truck
• A falling fluid level with no leak at the pan or case
• Crushed fins or a bent core after a hit from road debris
• Rusted, flattened or kinked lines that restrict flow
• Shifts that turn harsh or slip after the fluid level has dropped, or fluid that smells burnt

How to confirm before buying

Clean the cooler, fittings and lines, drive the truck to full temperature, then look again with a light. Fluid that appears at a line connection may only need the line reseated or its seal replaced, but a weeping core seam or a damaged core means the cooler has to go. Leaks at the transmission-side cooler connections are a documented pattern across 8HP applications; the BMW bulletin we cover in our ZF8HP BMW 3 Series common problems guide shows how fluid loss there is traced. If shift quality has already suffered, read the ZF8HP common problems guide first, because a transmission that ran low may need more than a cooler.

Fitment

This cooler and line assembly came off a 2016 Ram 1500 with the 8-speed automatic. Ram offered the 8-speed behind more than one engine that year, and cooler, line routing and fittings can differ by engine and drivetrain, so compare the part numbers, mounting points and line ends against the cooler on your truck before you install it. If you are unsure, send us your year and VIN and we will check it. Trucks with the six-speed automatic are not a match. It is a used part, so expect normal cosmetic wear. For other parts for this transmission family, see the ZF 8HP collection.

Install notes

• Disconnect the battery, place a drain pan under the cooler and line connections, and cap the open ports so dirt cannot get in.
• Use new seals or O-rings at the line connections and make sure each quick-connect fitting clicks fully home.
• If the old cooler failed after a transmission problem, flush the lines and cooler before a rebuilt unit goes in so debris does not return to the valve body.
• Refill only with Mopar ZF 8&9 Speed ATF or an equivalent such as ZF LifeguardFluid 8, as Ram's user guide specifies.
• Set the level hot with ZF's procedure: engine running, fluid at 30 to 50 C, filled until it just runs from the fill hole.

If the transmission ran low long enough to slip, plan for internal work with the 8HP70 master rebuild kit, and on the 3.6L V6 trucks, which use the 845RE version of this transmission, a worn valve body can be replaced with the 8HP45 valve body.

Will this fit my 2016 Ram 1500?

It came off a 2016 Ram 1500 with the 8-speed automatic. Cooler and line layouts can differ by engine and drivetrain, so compare part numbers, mounts and line ends with your original, or send us your VIN and we will check it.

Are the cooler lines included?

Yes. The cooler comes with its attached lines, which matters because the line connections are a common leak point.

What fluid does the 2016 Ram 1500 8-speed use?

Ram's 2016 user guide calls for Mopar ZF 8&9 Speed ATF or an equivalent. ZF LifeguardFluid 8 is the ZF specification for the 8HP. Do not mix in ATF+4 or a universal fluid.

How much fluid will I lose replacing the cooler?

Some fluid drains from the lines and cooler, so top up afterward and check the level hot with the engine running using the fill-hole method, not a guess.

Is this a new part?

No. It is a used original-equipment cooler with lines, so expect cosmetic wear. Inspect it on arrival and pressure-check or flush it before installing if your transmission had an internal failure.

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