48RE Transmission Cooler 2003-2007, new and ready to install. Fits the 48RE. Ships fast from the USA.
Factory steel cooler lines on a 2003-2007 Dodge Ram 2500 or 3500 with the 5.9L Cummins and 48RE automatic live a hard life: road salt, heat cycling and engine vibration work on them for years until the crimps and clamps start to seep. This listing is a replacement cooler line kit for that truck, not a radiator-style cooler. As the photo shows, it is three black braided hoses with swivel ends, two threaded adapter fittings, two hose barb fittings, two copper sealing washers and two O-rings, enough to replace the whole transmission cooling circuit in one job.
A 48RE turns a lot of Cummins torque into heat, especially when the converter is unlocked on a grade or with a trailer behind it. The cooler lines carry hot fluid out of the transmission to the cooling circuit at the front of the truck and bring it back to feed lubrication to the bushings, planetaries and clutches. The 48RE leans on that circuit harder than earlier RE units because it raises line pressure when overdrive or lockup applies, so the pump is moving more oil, more of the time. If a line leaks, the transmission loses fluid; if a line is crushed or kinked, flow drops and temperature climbs. GEARS Magazine gives about one gallon per minute as the minimum healthy cooler flow and about 200 F as the ideal maximum fluid temperature.
Wipe the lines clean from the transmission fittings to the front of the truck, take a 20-minute drive to get the fluid hot, and trace the first wet spot. A leak right at the case fitting can be the fitting itself, which this kit also replaces. If nothing leaks but the truck still runs hot, measure flow at the return line with a flow meter or a timed container; low flow with good lines means the restriction is in the cooler or the pump, and our 48RE pump failure symptoms guide explains how to tell. For the overheating failures that follow a lost line, read 48RE Ram 3500 Cummins common problems.
The kit is listed for the 48RE in 2003-2007 Dodge Ram 2500 and 3500 trucks with the 5.9L Cummins. Factory routing changed with cab, bed and cooler options, and some trucks already have an aftermarket cooler or relocated lines, so compare the lines and end fittings on your truck with the photo before you order. If your truck has been modified or you are not sure, send us the year and VIN. Every 48RE part we stock is on the 48RE parts page.
A lost line can cook the fluid quickly. If the truck now shifts soft or slips, a 48RE valve body for 2003-2007 or a converted 48RE valve body may be the next step after you check the clutches.
| Fits | 48RE 2003-2007 |
| Part type | Transmission Cooler |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
It is a cooler line kit. It replaces the hoses and end fittings that connect the transmission to the cooling circuit, not the heat exchanger or air cooler itself.
It is listed for 2003-2007 Dodge Ram 2500 and 3500 with the 5.9L Cummins and 48RE automatic. Compare the end fittings on your truck with the photo, and send us your VIN if the truck has an aftermarket cooler.
Three braided hoses with swivel ends, two threaded adapters, two hose barb fittings, two copper washers and two O-rings, as shown in the photo.
ATF+4. A pan service fill on the 48RE is about 3.8 liters, but replacing lines loses some extra fluid, so add slowly and check the level hot in Neutral.
Yes if the transmission has failed, overheated or shows debris in the pan. Flushing keeps old material from going straight back into the unit.
Only if a line is kinked or crushed. Measure cooler flow first; about one gallon per minute is the minimum. Low flow with good lines points to the cooler or the pump.
