How Does Air Get in Hydraulic Trailer Brake Lines Every 2 to 3 Months

Published 11/11/2014

Products Featured in This Question

Dexter DX Series Electric Over Hydraulic Brake Actuator for Disc Brakes - 1,600 psi

(129)

$1110.02

Replacement Fill Cap with Gasket for Dexter DX Series Electric Over Hydraulic Brake Actuators

(34)

$38.76

Question:

We have a trailer with your equipment. it works flawlessly when it doesnt have air in the brake lines, but it seems to get air in the lines every 2-3 months and has to be bled. im curious as to what can cause the air to get into the lines so often and if this is preventable in anyway. we are pulling the trailer with 2013 and 2014 dodge and ford 450 and 3500s.

asked by: Marshal F

Expert Reply:

Air can get into hydraulic brake lines from a leak in the line somewhere or at a fitting, via the cap on the master cylinder, or at a leaky wheel cylinder. A leak that is slow can be hard to find but it could eventually drain the master cylinder causing it to push through air. You would notice low fluid levels when you go to bleed the brakes if a leak was left unchecked for long enough.

You would probably be able to find a leak when bleeding the brakes simply because there is more pressure in the lines then when the trailer is just sitting. A leaky wheel cylinder is easily noticeable because there would be brake fluid on the back of the tire and wheel.

If you suspect the cap to be leaky on your Dexter brake actuator, # K71-651, then use # K71-685-00 as a replacement.

expert reply by: Michael H