4L60E 6AN Transmission Cooler Line Kit, 15 ft Hose

A 6AN cooler line kit for GM 4L60E and 4L65E trucks and cars: 15 feet of hose, swivel hose ends, and adapter fittings, enough to run both the feed and return side from the transmission to the radiator tank or an auxiliary cooler. The hose is a three-layer build with an NBR inner tube, a braided polyester reinforcement layer and a CPE rubber outer cover, rated at 650 PSI working pressure and 1180 PSI burst, which is far above what a 4L60E cooler circuit ever sees.

This is the fix when the factory steel lines have rusted through at the frame clips, the crimped rubber sections have started weeping at the ferrules, or you are adding an external cooler for towing or a swap and the stock lines no longer reach. A leaking cooler line on a 4L60E does not just make a mess: once the level drops you get delayed engagement, slipping on the 3-4 shift and burnt fluid, and a cooler circuit restricted by a kinked line starves the rear lube circuit and cooks the converter clutch.

On the truck: drain the cooler circuit into a pan, cut out or unscrew the damaged lines, and check the thread on your transmission and cooler ports before assembly so you use the correct adapter from the kit. Cut the hose square with a fine-tooth blade or AN hose cutter, tape the end first so the braid does not fray, fit the swivel ends, and route the lines away from the exhaust and anything that moves. Clamp the hose every foot or two, top off with the correct ATF, and check for seeps at operating temperature.

Temperature rating is listed as -4 to 212 F, so keep the hose clear of the exhaust manifold and catalytic converter. The hose also handles engine oil, gasoline and diesel if you have leftover length for another job.