Allison 1000 Braided Transmission Cooler Line Kit LBZ/LMM

The factory transmission cooler lines on 2006-2010 GM 2500HD and 3500HD trucks with the 6.6L LBZ or LMM Duramax and the Allison 1000 are formed steel tube with short rubber sections. They run low along the frame rail behind the front wheel, and in salt country the tube pits from the outside in. The first sign is usually a wet stripe down the crossmember and a slow drop on the dipstick; the failure mode after that is a line letting go at highway speed and dumping the pan, which will cook the clutches in under a mile.

This kit replaces both the feed and return runs between the transmission and the cooler with braided hose and the adapter fittings needed to mate to the case ports and the cooler. The hose is rated 840 PSI working and 3,360 PSI minimum burst, with an oil-resistant synthetic rubber liner, a textile braid layer, and an abrasion-resistant outer cover. Continuous service temperature range is -40 to 257 degrees F. Line pressure on a healthy Allison peaks well under 300 PSI even with the fluid fully heated, so the hose is working nowhere near its limit.

Installation is a driveway job on a lift or jack stands. Drain or catch what comes out of the lines, unbolt the factory tube from its frame clips, break the fittings loose at the transmission case and at the cooler, then thread the adapters in and route the new hose along the same path. Keep the hose off the exhaust and away from the sway bar, snug the fittings, refill, and run the truck up to temperature to check for weeps. Fits Allison-equipped trucks only, 2006-2010.