How to Bleed Your Hydraulic Brake System: A Step-by-Step Guide

Learn firsthand from a trailer manufacturer that allows you to buy a custom trailer

with our hydraulic brake system, at DiamondC.com.

Safety First

Before starting, take the necessary safety precautions:
✅ Make sure people around you are aware that you are working underneath the trailer.
✅ Secure the trailer on a stable lift or jack stands.
✅ Remove the wheels to access the brake components.

Tools & Materials You’ll Need

• DOT 3 or DOT 4 Brake Fluid
• 7/16" Wrench or Socket
• Brake Fluid Reservoir
• Auto Filler (if available)

Step 1: Inspect the System

Before beginning the bleeding process:
🔹 Ensure all fittings are tight.
🔹 Visually inspect the brake fluid level in the reservoir.

If you don’t have an auto filler, have someone assist by manually refilling the reservoir as needed.

Step 2: Start Bleeding from the Rear Axle

Begin the bleeding process at the rear axle, as this helps push any air bubbles back toward the reservoir. Follow this order:

1️⃣ Rear Axle
2️⃣ Passenger Side Front
3️⃣ Driver’s Side Front

This sequence ensures the air bubbles travel toward the reservoir for proper removal.

Step 3: Loosen the Bleeder Valve

• Use a 7/16" wrench to loosen the bleeder valve.
• Attach a brake fluid reservoir or a clear hose to capture the expelled fluid and air.

Step 4: Activate the Brake Pump

1. Pull the Breakaway Pin to engage the brake pump.
2. Once the power is on, open the bleeder valve.
3. Watch for air bubbles in the brake fluid—this indicates air is still in the system.

Once the fluid runs clear with no bubbles, close the valve immediately to prevent leaks and ensure proper bleeding.

Step 5: Complete the Process

🔹 Close the auto-filler or manually top off the brake fluid.
🔹 Turn off the brake pump.
🔹 Reinsert the Breakaway Pin to finalize the process.

Final Check

Listen for a humming sound when engaging the pump to verify that your brakes are properly bled. The hum should last no more than two seconds before the brakes engage.

That’s it! Your hydraulic brake system is now bled and ready to go.

🔧 Regular brake maintenance is key to ensuring the safety and longevity of your trailer. Stay tuned for more maintenance tips and guides! Click here to see the full lineup of brake actuators.