Replaces the factory thermal bypass valve on 2019-2024 Ram 2500/3500 6.7L Cummins so transmission cooler flow is open cold, not gated by a thermostat.
On the 2019-2024 Ram 2500 and 3500 with the 6.7L Cummins, a transmission that starts running hot under load often has a perfectly good cooler that simply is not getting fluid. The thermostatic bypass valve where the cooler lines meet the transmission controls that flow, and when its element sticks partly closed the 68RFE or Aisin AS69RC keeps recirculating hot fluid. This kit replaces that valve with an open-flow billet aluminum housing, manufacturer part number ASP-CS21-00139004, with O-rings included.
From the factory, the bypass holds fluid away from the cooler until the transmission reaches operating temperature, which helps warm-up and fuel economy. The weakness is the thermostatic element. After years of heat cycles it can hang between open and closed, and the truck only shows it when it is working hardest: towing up a grade, when cooler flow matters most. This housing has no element, so fluid goes out to the cooler and back on every cycle regardless of temperature. Nothing about the transmission's own hydraulics changes; it only affects the cooler circuit.
Heat is the leading killer of the 68RFE, and a hot truck is not automatically a bad bypass. GEARS Magazine's overheating checklist covers restricted lines, a plugged cooler, a plugged filter, overloading past the tow rating, engine overheating and fan clutch problems. Do a flow test at the return line: under one gallon per minute with clean lines and a clear cooler is the signature of a bypass that is not opening. If the truck also has harsh or slipping shifts, read our 68RFE shift problems guide first, because heat damage and a hydraulic fault can look alike. The 68RFE Ram 3500 common problems guide explains how the clutch and converter failures on these trucks connect back to fluid temperature.
This version fits 2019-2024 Ram 2500 and 3500 trucks with the 6.7L Cummins and either the 68RFE or the Aisin AS69RC. Transmission Digest notes that Ram changed the 68RFE again for 2019, and the bypass changed with that generation, so 2013-2018 trucks need the earlier style valve instead. Check that the valve on your truck matches the photos and bolt pattern, or send us your year and VIN to confirm. Every part we stock for this transmission is on the 68RFE parts collection.
With hand tools this is a short driveway job. Place a drain pan under the valve, release the two cooler lines from the factory bypass, unbolt it from the transmission and clean the mounting face. Lubricate the new O-rings with clean ATF+4, set the billet housing in place, tighten the bolts evenly so the O-rings seat flat, and reconnect the lines. Start the engine, top off, then drive until the fluid reaches at least 160 F, the minimum FCA specifies for checking level, and check again. Look for weeping at the O-ring lands after the first full heat cycle. If you are replacing the valve after a failure, plan on servicing the hydraulic side too: the 68RFE valve body 5170877AA covers 2007-2024 units, and the 2019-2025 governor pressure solenoid is the matching sensor for this generation.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. This kit is for 2019-2024 trucks. The 2013-2018 trucks use a different bypass valve design.
Yes. On 2019-2024 Ram 2500 and 3500 6.7L Cummins trucks the valve location and cooler line connections are shared between the two transmissions.
Warm-up takes longer in cold weather because fluid goes straight to the cooler. Once the truck is working, the cooler can never be blocked by a stuck element.
No. It is a hydraulic part on the cooler circuit only. No programming, cutting or line changes are needed.
ATF+4. Check the level hot, at 160 F or above, after the cooler circuit has filled.
