_810.png "01-10 Duramax Transmission Cooler Lines Repair")
Next up in our Blog series is replacing leaky transmission cooler lines on our LBZ Duramax. This is a very common issue and happens because of another cheap design by GM. While you can go back with OEM lines, we highly recommend either having a local hose shop build your hoses and fittings or buying a kit like the one we'll be installing. Both Deviant Race Parts and Fleece make repair line kits. They do slightly differ as the 01-05 will be different than the 06-10 trucks.
Deviant has a good PDF install on these: https://www.injectedmotorsports.com/product/deviant-transmission-cooler-repair-lines-2006-2010-gm-duramax
Notes: (We have added notes and pictures that will aid the installation.)
Tools needed:
- flat head screwdriver
- nut driver
- Crowfoot (line wrench) 1 1/4" for factory nuts and 1" for the Deviant nuts
- Hose cutter and dike plyers
- Ratchet and Extention
- Catch pan
- Crescent wrench's
1. When doing this install you'll typically lose around half a quart of fluid, after installing make sure there are no leaks and take it for a drive to get the trans up to temp, and then check your level and add ATF if needed.
2. I zip-tied the lines going back to the transmission together and up out of the way so nothing sharp would puncture a hole in it.
3. Install times might vary but on average 2 hours would be pretty standard for this and shown in the video below can be done in your driveway.
Here's a picture of one of the leaky lines.
Factory Lines with grill and shroud removed. The right-hand side line goes to the top of the transmission, and the left side goes to the top fitting on the LH side of the radiator.
Factory Lines disconnected. BE SURE to use a backup wrench on the cooler housing as the aluminum can crack easily
Top view of the new trans lines, the top fitting is a 90-degree, and the bottom is a 45-degree fitting.
Top view of the crowfoot socket with an extension to loosen or tighten the hard-to-reach nut.
Picture of the line wrench or (crow's foot) socket which is handy for this install.
Deviant Race Parts 1/2" Kit
