Fifteen feet of 750 PSI braided AN6 hose with the swivel ends and adapters to run a 4L60E or 4L65E to a remote cooler and bypass the radiator.
Heat kills more 4L60E and 4L65E transmissions than anything else. If you tow with a Silverado, Sierra, Tahoe or Yukon, or run one of these units behind a built engine or in an LS swap, a remote cooler on dedicated lines is the cheapest protection you can buy. This kit is the plumbing for that cooler. You get 15 feet of 6AN braided hose rated at 750 psi working and 2250 psi burst, four swivel hose ends (two straight and two 90-degree), two hose separator clamps, and adapters for 1/4 inch NPT and 1/4 inch NPSM ports.
Fluid heated by the converter and the clutch packs leaves the case through one cooler port, runs through the cooler, and returns through the other port to lubricate the gear train. On a stock truck, the cooler is a tank inside the radiator. That tank can only bring the fluid down to about engine coolant temperature, and on a hard pull it can add heat. Running the hose to an external cooler, or to a stacked cooler and the radiator in series, takes heat out before the fluid returns to the case. The braided hose has a CPE core with 304 stainless wire and a nylon outer braid. It holds up against the abrasion that splits rubber line where it touches a frame rail, and it is rated from -22F to 248F.
Check the fluid level and condition hot, and read any stored codes. A slipping TCC that sets P0741 or a pressure fault that sets P0748 is a valve body or solenoid problem that a cooler will not fix. Our 4L60E common problems guide covers how to tell them apart. If the fluid is already burnt and full of friction material, the unit needs internal work first. A new cooler only protects a healthy transmission.
The kit is sold for 4L60E and 4L65E cooler lines. These units do not all use the same port thread. Most cases take a 1/4 inch pipe-size fitting, and the kit includes NPT and NPSM adapters for that. Some units use a 9/16-18 fitting instead, which needs a different 6AN adapter. Remove a factory fitting and measure the threads before you start. About 0.52 inch points to the 1/4 pipe size, and about 0.557 inch means 9/16-18. Check your cooler's ports as well, and send us your year and VIN if you are unsure. For other parts for your truck, see our 4L60E collection page.
| Fits | 4L60E / 4L65E cooler lines |
| Hose length | 15 feet 6AN |
| Working pressure | 750 psi (2250 psi burst) |
| Temp range | -22F to 248F |
| Construction | CPE core, 304 steel wire, nylon braid |
| Includes | 4 swivel ends, 2 clamps, NPT/NPSM adapters |
| Ships from | USA |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Usually, if your case has the 1/4 inch pipe-size ports. The kit includes NPT and NPSM adapters for those. Some units use a 9/16-18 fitting, which needs a different adapter. Measure a factory fitting before you start.
On most trucks and swaps, yes. 15 feet covers both the feed and return lines from the transmission to a cooler behind the grille, with some length to spare for routing.
In hot climates and for towing, many builders run the external cooler alone or in series after the radiator. In very cold climates, keeping the radiator in the loop helps the fluid warm up. Either way, use a cooler sized for your load.
Dexron VI ATF. Check the level hot after the new lines and cooler have filled, because they hold extra fluid.
No. A cooler protects a healthy unit. If it already slips or the fluid is burnt and full of debris, diagnose and repair it first.
