Hydraulic Trailer Brakes are Slow to Release

Updated 04/10/2025 | Published 09/15/2012

Question:

having problem with slow brake release

asked by: Richard

Expert Reply:

For hydraulic brakes that are dragging or slow to release it could be a number of issues. If you have used the wrong type of fluid required by your brake set up, that could cause the problem. There may also be a foreign object in the master cylinder blocking the correct flow of fluid. For either of these you will need to drain the system, check for foreign objects and remove them, flush the system and refill/bleed the system using the correct brake fluid.

If your system has a parking brake check that it is functioning properly and can move freely.

If you have drum brakes, make sure they are properly adjusted. Also make sure you are using a drum actuator for drum brakes or a disc actuator for disc brakes.

If the system has a breakaway kit, make sure that there are no broken or corroded connections in the wiring and that the battery is fully charged and the pin in the switch is all the way in.

expert reply by: Michael H

Mehdi

3/27/2025

Hi Michael I have three axles trailer Kaufman working with brake actuator ( drum) hydraulic Brakes and release working with delay I changed all brakes mechanism for all 6 tires Two times flush the fluid ( DOT 3 ) checked connections and make sure there’s no leaking Checked battery voltage But still brakes are slow to brake and release

Jameson C.

3/27/2025

@Mehdi Hows the shock on the coupler? Sounds like it might be a bad shock or the mechanism isn't allowing the coupler to move like it needs to.

Mehdi D.

3/28/2025

@JamesonC I changed all my 6 tires brake mechanism Checked all lines Took out air from brake cylinder Checked battery voltage Checked emergency switch when I push brake pedal a bit ( it’s better to say touch brake pedal) brakes on trailer works very aggressively ( also with delay) Even when I put brake gain on my truck to 0.5 !! ( it’s adjustable from 0 to 10 ) And release with delay !!

Jameson C.

3/31/2025

@MehdiD Can you test for voltage on the output circuit that runs to the actuator to see if only .5 volts is making it to the actuator when you touch the brakes or if it's getting the fully 12 volts? Does the system by chance lock up brakes when you apply a blinker?