Why is the Hole So Small in Trailer Brake Master Cylinder Fittings

Question:

What is the purpose of this connector with the pinhole size opening in it? I have it on my trailer and it makes it nearly impossible to bleed the brakes or get them to engage to test them. Is it really necessary to have it?

asked by: Michael C

Expert Reply:

The small opening in master cylinder fittings like # T1209800 is designed to provide the proper amount of fluid and pressure through the brake lines. Bleeding trailer brakes manually is difficult. You could use a power brake bleeder, vacuum style bleeder like # PTW87030, or change methods of how you manually bleed the brakes.

What I recommend is to attach the trailer safety chains together then position a long 2x4 upright between the chains and the front of the coupler. Use the long board to push in the actuator. the longer the board the easier it will be.

expert reply by: Michael H