SeaStar and Uflex Hydraulic Steering Bleed Procedure

Department: Steering Systems | Level: Intermediate | Est Cost: $130

Air entrapment in hydraulic steering systems is the primary cause of "spongy" helm response and loss of boat control. Traditional bleeding methods require two people and often fail to remove micro bubbles trapped in long hose runs. This protocol details the "One Person" bleed method using a gravity fed high capacity reservoir system.

Section 1: Required Equipment

The standard "bottle and pin" bleed kit provided by SeaStar holds insufficient volume (1 quart) for a complete system flush. We recommend a 3 quart system to ensure continuous head pressure.

Essential Service Tools

• Marine Tech Bleed System: Includes a 3 quart reservoir, quick connect fittings, and 25 feet of return line.
• Thin Wrench (Included): Specialized wrench for accessing cylinder bleed nipples in tight splashwells.
• Helm Adapter: Threaded brass fitting to connect the reservoir to the helm pump.

Consumables

• Hydraulic Fluid: SeaStar HA5430 or Mil Spec 5606 Aviation Fluid.
• Absorbent Pads: To catch overflow at the cylinder.

Section 2: System Setup

1. Cylinder Connection

Connect the clear return line to the bleed fittings on the steering cylinder. The Marine Tech system uses a "Quick Connect" bridge that joins both bleed fittings to a single long return hose.
Note: If flushing old black fluid, disconnect the return line break point and route it into a waste bucket. Do not recirculate burnt fluid back into the new reservoir.

2. Helm Connection

Remove the fill plug on the helm pump. Ensure the helm is completely full of fluid before starting. Thread the Helm Adapter into the fill port.
Important: Connect the 3 Quart Reservoir to the adapter. Elevate the reservoir (hang it from a T Top or windshield frame) to create gravity pressure.

3. Purging the Adapter

Before opening the bleed fittings, verify no air is trapped in the helm adapter itself. Slightly loosen the quick connect fitting at the helm until fluid drips out, then retighten. This ensures a solid column of fluid enters the pump.

Section 3: The Bleed Procedure

4. Open the System

Go to the stern. Open BOTH bleed fittings on the steering cylinder using the thin wrench. Because we are using a closed loop return system, fluid will not leak out; it will circulate.

5. Port Side Bleed

Go to the helm. Turn the wheel slowly to the PORT side. Watch the clear return line coming back to the reservoir. You will see a stream of bubbles exiting the cylinder. Continue turning until the fluid in the return line is perfectly clear and bubble free.

6. Starboard Side Bleed

Turn the wheel slowly to the STARBOARD side. This purges the opposite side of the cylinder. Again, watch for bubbles in the return line. Continue turning until clear.

7. The Physical Check

Go back to the motor. Manually push the engine from lock to lock. This mechanical agitation helps dislodge any stubborn air bubbles trapped in the cylinder end caps. If you see more bubbles appear in the line, go back to the helm and turn some more.

Section 4: Shutdown and Final Check

8. Closing the Loop

Close both bleed fittings on the cylinder tight. Remove the return lines.

9. Helm Disconnect

Disconnect the reservoir from the helm adapter. Remove the adapter.
Fluid Level Check: The fluid level should be approximately 1/4 inch below the bottom of the fill threads. If it is too full, it will overflow when the fluid expands in the hot sun.

Conclusion

A properly bled system should feel solid. If you can turn the wheel more than 1/4 turn before the engine moves, there is still air in the system. The high volume gravity feed system is the only way to effectively remove this air without a $1,000 power purge machine.

For Seastar steering repair kit, visit the Seastar Seal Kit Steering Section.