Truck Transmission Repair: Cooler Line

What You'll Need
Transmission clamp
Vehicle lift
Transmission jack
Replacement fluid, assembly lube
Shop rags, drop cloths
Torque wrench

Truck transmission repair is not an effortless task. However, when you finish the job properly, you will again enjoy a cooler line that works as it should.

Truck transmission cooler lines prevent your transmission from overheating, especially during summer days when you are stuck in a traffic jam with your air conditioning on full blast. Cooler lines carry the automatic transmission fluid further than the transmission’s hot gears. The fluid cools a little during the transfer through the lines prior to returning to the truck’s transmission. Without such a cooling mechanism, its transmission fluid can become extremely hot and cause the transmission to stop working.

Step 1 – Familiarize Yourself with the Cooler Line Functions

Once automatic transmission fluid reaches a particular temperature, its viscosity alters and the liquid thins significantly. The transmission fluid no longer accurately lubricates the moving parts of the transmission, while the truck's gears can stick or never shift at all. The fluid, being a lubricant, cools the transmission in order to keep it from bending and warping.

The cooler lines aid the fluid in cooling by eliminating it from the warm transmission, then permitting it to pass along the cooler zone. Remember that cooling also prolongs the fluid’s life. Nevertheless similar to any truck tubing, the transmission cooler lines can develop leaks. Leaks will cause your transmission to overheat and fail if you do not restore the cooler lines at once.

Step 2 – Buy Transmission Cooler Lines

You can purchase cooler lines designed specifically for your truck’s model. Trucks need two separate lines: a return line and a feed line. These lines are twisted into particular shapes to mount to the truck’s underside. While regular brake lines can be modified in order to fit the truck, they are typically too short for the task and necessitate huge rerouting of the truck’s transmission cooler lines.

Take note that standard cooler line sets are available for $30 dollars or less. If you prefer the most proficient cooling system for the truck’s transmission, consider adding a second cooler line to the factory-installed line. Keeping your transmission fluid cool will prolong the entire transmission’s life considerably.

Step 3 – Replace the Cooler Line

Since the detached lines will possibly weep fluid, you need to place a drop cloth in the floor after raising your truck with a jack. Next drain the transmission fluid in a pan and reserve it to fill up the system afterward. After removing the old cooling lines, you will deal with the radiator. You need to verify that the replacement exactly match the former parts. Given that hard tubing is prone to leaks once bent extremely, you should bend the tubing only lightly to preserve its original shape.

Repair and install first the top line to prevent blocking access along with the lower line. Install the bottom line; then tighten all the connections with an adjustable torque wrench. Lastly refill your truck’s transmission fluid. Test the lines for any leaks before you begin driving the vehicle again.