How to Add Fluid to Hydraulic Steering

When your wheel feels extra loose or requires extra effort, it’s time to add hydraulic fluid.

Owning a new boat ultimately brings the reality of performing both scheduled and nonscheduled maintenance. This doesn’t have to be onerous, though — have fun with these projects and make them an enjoyable part of your overall boating experience. One issue that you might encounter is a hydraulic boat steering problem.

How to Add Hydraulic Fluid
This diagram shows how to add hydraulic boat steering fluid.Boating Magazine

In this situation, you'll need to get some hydraulic-steering fluid that meets Mil-Spec H-5606C standards, such as Sea Star/Bay Star No. HA 5430; an adapter hose, like Sea Star No. HA 5438; and a pushpin from the bulletin board in your office. A rag also helps. Sea Star hydraulic steering fluid is prevalent in most boating centers across the United States.

  • Thread filler tube into helm pump
  • Thread bottle of fluid onto filler tube
  • Poke a hole into the bottom of the bottle (or, cut the bottom off and create a funnel)
  • Turn bottle upside down (like an IV)

Note: At all times, be sure there is fluid in the filler tube, if it drains out you are pumping air in the system and you will need to start over

How to Add Fluid to Hydraulic Steering

  1. Thread filler tube into helm pump.
  2. Thread bottle of fluid onto filler tube.
  3. Poke a hole into the bottom of the bottle (or, cut the bottom off and create a funnel).
  4. Turn bottle upside down (like an IV).
  5. Turn steering wheel hard to starboard.
  6. Open starboard bleeder nipple located on the steering cylinder.
  7. Turn steering wheel to the port side pumping air/fluid out of bleeder fitting.
  8. When an air free stream is seen, CLOSE bleeder nipple.
  9. Continue turning to the PORT side until engine comes hard over.
  10. Open port bleeder nipple located on the steering cylinder.
  11. Turn steering wheel to the starboard side pumping air/fluid out of bleeder fitting.
  12. When an air free stream is seen, CLOSE bleeder nipple.

The above will ensure that you have properly bled the system free and clear.

TIP--puncture the bottle on the bottom side, not the very bottom, with the pushpin. Doing so enables you to place the pushpin back in and store a partially-full bottle on a shelf without leaks.

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