Does The Hydrastar Brake Actuator HBA16 Need To Be Bled Manually?  

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Expert Reply:

Hi Victor!

The Hydrastar Disc Brake Kit w/ Actuator for Tandem Axle Trailers - 13" Hub/Rotor - 8 on 6-1/2 - 7K # HSE7K-T1 uses the Hydrastar Electric Over Hydraulic Actuator # HBA16 and used DOT 3 or DOT 4 brake fluid. I have the full manual process listed below, but be aware, it is a process. Do you have someone that can give you a hand if you go this route? It is pretty needed for this one.

That said, you can use a vacuum bleeder if you have one or have access to one. It will make this a much easier experience.

Bleeding Instructions For Hydrastar # HBA16
1. It typically is much easier to bleed the brakes with two people working together or use of a power bleeding device.
2. Special care must be taken to insure that the Hydrastar unit does not run out of brake fluid. Check the fluid level frequently during the bleeding process.
3. Block the wheels on the trailer and towing vehicle.
4. If the trailer is equipped with drum brakes, check that the brake running clearances are properly adjusted consistent with the trailer manufacturer’s recommendations. Even the slightest amount of brake drag will generate heat and will damage the trailer brake system voiding the manufacturer’s warranty.

! CAUTION – Failure to properly adjust the brakes on trailers equipped with drum brakes can result in sluggish operation of the Hydrastar unit. Eye protection should be worn at all times while bleeding the Hydrastar unit and trailer brake system.

5. Remove the dust cap from the bleed screw on the Hydrastar unit and install plastic tubing onto the bleeder
6. Immerse the free end of the plastic tubing in a clean container partially filled with brake fluid.
7. With eye protection on, open the bleeder screw one half turn on the Hydrastar unit. Take care to protect yourself and the trailer from brake fluid expelled from the bleeder.
8. Activate the Hydrastar unit by turning on the ignition switch and pressing on the brake pedal or the manual control on the in-cab controller.
9. Watch the free end of the bleeder hose for air bubbles escaping into the container.
10. Continue to bleed until the fluid becomes clear and free of bubbles.
11. Tighten the bleeder screw, turn off the Hydrastar unit, and remove the plastic tubing from the bleeder screw. Bleeding of the Hydrastar unit is now complete.
12. Install plastic tubing onto the bleeder screw of the wheel cylinder/caliper.
13. Immerse the free end of the plastic tube in a clean container partially filled with brake fluid.
14. With eye protection on, open the bleeder screw one half turn on the wheel cylinder/caliper farthest from the Hydrastar unit. (If towed vehicle has multiple axles, always start with the rear axle first.)
15. Activate the Hydrastar unit. (Turn the ignition switch on and press on the brake pedal.)
16. Watch the free end of the bleeder hose for air bubbles escaping into the clear container. Continue to bleed the wheel cylinder / caliper until the fluid becomes clear and free of bubbles.

! CAUTION – Do not run the Hydrastar unit without adequate brake fluid in the reservoir as it will damage the unit and void the manufacturer’s warranty. Check all bleeder screws to ensure that they are securely closed and do not leak.

17. Tighten the bleeder screw, turn off the Hydrastar unit, and remove plastic tubing from the bleeder screw. Bleeding of the wheel cylinder/caliper is now complete.
18. Refill the Hydrastar unit with brake fluid.
19. Continue the above process (steps 12 through 18) on the next farthest brake away from the Hydrastar unit. Repeat these steps until all the brakes have been bled.

! WARNING – Failure to properly adjust the trailer brakes and to properly fill and bleed the Hydrastar™ unit and brakes may result in sluggish brake performance. This may result in serious or fatal injuries and / or property damage. As a precautionary measure, it is recommended to bleed the brakes a second time after the trailer has been in service for 7 – 10 days. It also recommended to check the temperature of the hubs on a regular basis to insure that the trailer brakes are not dragging.

expert reply by: Lazer S

0

Victor B.

10/1/2025

Thanks! I have a vacuum bleeder and just needed to be sure it would work with the HBA16 unit. (My wife of 40 years is very experienced in the 2 person brake bleeding procedure, if it came to that) "Push!...let off...push...let off" ;-)

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Lazer S.

10/1/2025

@VictorB Haha! Bleeding brakes is a pain in the butt, but it does need to be done. That vacuum bleeder will make it easier for sure. We need to look into carrying a few of those. Would be big sellers! And holy cow! Congrats on 40 years! Just don't have her hold the flashlight when you are working on something. It never went well for me when I was a kid and my dad was working on an engine or something. : P Let me know if there is anything else I can help with. : )

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