Why Would Trailer Brakes Stop Working After Replacing Hydraulic Brake Line

Question:

Now brakes not working Replaced a brake line

asked by: Tijuan T

Expert Reply:

Sounds like you replaced a hydraulic brake line and now the trailer brakes do not seem to be working. Typically when this happens it's because the brakes need to be bled. When you open up a brake line it allows air to get in the lines which will compress when the brakes are applied instead of activating the assemblies. What you'll need to do is bleed the brakes and you'll get the brakes to work again. I attached a video below that shows how to do this.

First top off the master cylinder with appropriate fluid. Next you will want to pump the fluid from the master cylinder. You can do this by unbolting the plate that holds the lever in place and then use that lever to actuate the master cylinder and force the fluid through. On some units, you will have to manually activate it at the point where the hitch ball moves in and out. The model in the video has a lever underneath the unit you could use to actuate it.

Next, find the bleeder valve and open it. Take a rubber hose and slide it onto the bleeder itself and run the other end to a clear container. Using a clear container will allow you to see if any air bubbles rise up during the process. No bubbles means no air and that the system is full of just fluid.

expert reply by: Jameson C