2023 BMW 740i Trans Oil Cooler Line Replacement Cost

There is no specified replacement interval for transmission cooler replacement lines. However, high mileage vehicles may experience failure of these lines as their rubber parts will degrade over time due to age and heat from driving. More likely, the transmission cooler itself may fail, and the lines will be recommended as part of the repair. Transmission coolers can fail due to heat (in regards to radiator integrated ones) or due to collision.

When any transmission symptoms are present, the technician will first conduct a visual inspection of the vehicle, and note any observed issues. If the transmission issue is related to a leak on the transmission cooler or transmission cooler lines, those components will be inspected, and either resealed, or replaced. n the transmission. Once the suspected component(s) have been tested, any failed component must be replaced, and the transmission will be tested once again. Failed transmission cooler components are typically very easy to notice for the experienced technician.

Leaking transmission cooler line replacement is normally done without draining the transmission fluid, but the transmission oil cooler must be drained once the first line is disconnected from the transmission. After the transmission cooler stops pouring fluid from the lines, the remaining connections can be disconnected, and the new lines placed into existing retaining hardware. Once the transmission fluid cooler lines are reconnected, the servicing technician will refill the transmission with new fluid prior to reconfirming the repair.

We recommend comparing the factory part to an aftermarket part, and ensure the bends in the line are all correct. Many lines will not be correct when they are ordered, and must be bent into shape using specialty tools. This should be considered if planning on taking this project on as a DIY.

There are many types of transmission fluids, and they are not typically interchangeable. Consulting the owner's manual for your vehicle is the best way to ensure you have the correct fluid for your transmission. If improper transmission fluid is added, the resulting damage could be severe.

Most experienced DIYers can replace the transmission lines for the transmission fluid cooler. The experience is needed to ensure the fasteners are tightened properly to prevent leaks, but not so tight they cause them. If the manufacturer specification for those fasteners are followed, the task should not be a problem.