How do I Troubleshoot a Boat Trailer Brake Issue?

Boat trailers typically use a hydraulic braking system rather than the electric system that is common on other types of trailers. Boat trailers are frequently submerged in water and the hydraulic system withstands the damp conditions better than an electric braking system can. Hydraulic brakes on boat trailers are called surge brakes. These rely on the momentum of the trailer and the pressure that it puts on the hitch to activate and deactivate the braking system.

Instructions

    • 1

      Visually inspect the trailer and the ground beneath it for fluid. The brake system relies on hydraulic fluid and any leaks near the cylinder or along the lines may be affecting the effectiveness of the brakes. If any hydraulic fluid is apparent on the ground or along the lines, drain the lines and replace the worn parts.

    • 2

      Check the level of brake fluid in the reservoir. All of the trailer's cylinders may need to be replaced if the system has been dry for a lengthy period of time. If the reservoir has lost fluid, there is a leak somewhere in the system that requires repair before adding fluid and bleeding the brake lines.

    • 3

      Determine if the brakes on any of the wheels are functioning. Pull the breakaway cable until it locks. This should apply the brakes. Jack up and block the trailer until all wheels are off the ground. Turn each wheel toward the front of the trailer to see if the brakes engage and lock up. The master cylinder is usually functioning properly if any of the brakes are working. If this is the case, the problem is likely located in an individual brake.

    • 4

      Disassemble the wheel of the non-functioning brake. Check for frozen pistons, worn brake linings, bent lines, a leaky cylinder, grease or brake fluid on the shoes or drum, glazing on the drum or rotor and air in the lines. Repair as required.

    • 5

      Check the brakes for overheating after pulling the trailer. A faint burning smell, smoke or excessive heat generation in the wheel assembly area may indicate wheel bearing failure.

    • 6

      Test the master cylinder if none of the brakes are working. Without removing the orifice fitting, detach the brake line from the cylinder and use the lever to activate the cylinder. If no fluid pushes through the orifice fitting, remove it and check for a clog. With the orifice fitting removed, activate the cylinder again. If no brake fluid pumps out, the master cylinder is defective.