CSF 3850 OEM Style Replacement Radiator, Standard Output (2017-2025 6.7L Powerstroke, Secondary Radiator)

Fitment

Fits 2017-2025 Ford F-250 and F-350 Super Duty pickups with the 6.7L Powerstroke in Standard Output form. Starting in 2023, pickups were also offered with a High Output version of the 6.7L. This listing is the Standard Output part, so if you have a 2023-2025 High Output truck, call us with your VIN before you order. This is the secondary radiator only; the primary radiator is a separate part, and we carry the CSF 3849 for that loop. This part is listed for 2017-2025 trucks, so verify fitment by VIN, and check with us first on an F-450 pickup or chassis cab. See more parts in our Powerstroke section.

Why this part

The 6.7L runs a second, low-temperature cooling loop with its own radiator, degas bottle and thermostat. On every 2017-and-newer truck that loop cools the air-to-water charge air cooler and the fuel cooler. On 2017-2019 trucks it also carries the transmission cooler, which Ford moved to the primary loop for 2020. When the secondary loop runs low or cannot shed heat, it tends to show up as high intake air temperatures before the engine ever overheats.

That makes the secondary radiator worth replacing as soon as it leaks or gets damaged. CSF radiators are individually pressure tested and serial number certified, and they go through extensive in-house testing that includes wind tunnel, burst pressure, vibration, thermal cycle and salt spray corrosion testing. The 3850 uses an aluminum core with OE style plastic tanks and quick-connect inlet and outlet pipes. CSF is an ISO certified cooling system manufacturer that works with many OEM customers around the world.

One thing to rule out first: on 2017 and newer trucks the factory air-to-water intercooler can leak coolant internally into the intake. If you are losing coolant with no outside leak, or seeing white smoke or steam from the exhaust, have the intercooler checked before you blame the radiator. On 2017-2019 trucks, also inspect the plastic degas tanks, which crack or weep at the seams with heat cycles.

What you get

• One CSF 3850 OEM style replacement secondary radiator, Standard Output
• Aluminum core, OE style plastic tanks and quick-connect inlet and outlet pipes
• Radiator cap not supplied

Specifications

Features:

• Secondary Radiator
• OEM Replacement
• Drop-In Installation
• 1 Year Warranty

Specifications:

• Bottom Hose Fitting (in): 7/8 Left
• Top Hose Fitting (in): 7/8 Left
• Core Length (in): 39 3/8
• Core Material: Aluminum
• Core Thickness (in): 15/8
• Core Width (in): 20 11/16
• Cross-flow/ Down-flow: Cross Flow
• Hazardous Material: No
• Inlet Length (in): 21 3/8
• Inlet Width (in): 21/8
• No. Of Rows: 2
• Oil Cooler (in): No
• Outlet Length (in): 21 3/8
• Outlet Width (in): 2 1/8
• Radiator Cap Supplied: No
• Tank Material: Plastic
• Tech Note: O.E.M. Style Plastic Tank & Aluminum Core With Quick-Connect Inlet & Outlet Pipe

Manufacturer Warranty:

• 1 Year

Installation notes

CSF builds the 3850 to OE specifications for a true drop-in fit and a by-the-book installation. The quick-connect inlet and outlet pipes are OE style, and no radiator cap is supplied. Top up with the same coolant type the truck already runs, which your under-hood decal or VIN will confirm, and do not mix types. The secondary loop has its own degas bottle and its own capacity, so check and top off that bottle on its own after the job.

About CSF

CSF is a family-owned company in Rancho Cucamonga, California, that has built radiators and other cooling parts since 1947. It serves both the OE replacement market and the performance aftermarket, and it tests every design in-house. If testing turns up a weak point in a factory design, CSF engineers its replacement to be stronger.

Frequently asked questions

Is the CSF 3850 the primary or secondary radiator?

It is the secondary radiator, the one on the low-temperature loop. The primary radiator is a separate part. If you are chasing a leak and are not sure which radiator it is coming from, call the shop before you order.

Will it fit a High Output 6.7L?

This listing is the Standard Output part. High Output 6.7L pickups arrived for 2023, so if your 2023-2025 truck has the High Output engine, send us your VIN and we will confirm the right secondary radiator before you buy.

What warranty does it carry?

The CSF 3850 comes backed by a 1 year manufacturer warranty.

Questions on fitment? Call the shop at the number in the header. We install everything we sell.