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Tips for Bleeding the Hydraulic System
Basic Bleeding Procedure
Start at the helm closest to the steering cylinder (multi-helm only)
Remove the fill plug and install hose fitting and hoses
Wrap an oil absorb pad around the helm to prevent leaks
Ensure any other helms in the system have non-vented plugs installed, or leaks will occur
Connect hoses to the steering cylinder and loosen the bleed fittings by one turn
Connect 12V power
Switch on purge and check for leaks
Turn the steering wheel clockwise until the steering ram fully extends, and continue turning slowly for at least 30 seconds or until no bubbles are visible in the cylinder hose
Repeat counterclockwise as above
If there are additional helm stations, repeat the above steps as necessary
Set autopilot to Dealer Mode* and use 'Verify Steering Direction' to operate the pump in each direction for at least 30 seconds
Disconnect hoses and power cables. Tighten bleed fittings, verify fluid level in helm, and install plug
Operate the helm in both directions and check for smoothness and positive end stops
Operate autopilot and verify that the rudder moves smoothly
*To put the autopilot into dealer mode follow these steps:
From the GHC™ 20autopilot controller: Press the Menu Button > Set Up > System > System Information Press and hold the center soft key until Dealer Mode appears above it.
From the GHC™ 50 autopilot controller:
The GHC 50 autopilot controller does not require extra steps to access Dealer Mode.
From the main screen, press the three dots > Autopilot Setup > Autopilot Installation, and press OK to the caution message. The following options display under Autopilot Installation.
Wizards
Speed Source Setup
Steering system Setup
Compass Setup
Autopilot tuning
Restore Defaults
Tips for bleeding the hydraulic system
Performing any changes to a hydraulic system requires bleeding the system. Check with the helm manufacturer's owner's manual for brand-specific directions on bleeding the steering hydraulics on the vessel.
Use the proper amount of hydraulic fluid when installing the autopilot
The autopilot is considered the lowest station in the hydraulic steering system
Do not use Teflon tape on any part of the hydraulic system
If replacing the pump and contamination of the hydraulic fluid is suspected, flush the old hydraulic fluid and replace it with new fluid
If there are bleeding issues reusing hydraulic fluid, try using a fine mesh filter such as those for gasoline. A Power Purge (Seastar) or the Bubble Buster (Uflex) system has built-in screen filters on the pump pickup line
When performing the Autotune Steering direction, if it does not go hard over and give a "Pump Stall" error, air is still in the lines; consider using a power purge to bleed the system
Several steering systems and helms can quickly be bled by hand. Meanwhile, more complex systems may require additional equipment, such as a power purge, so it is recommended to seek a certified Garmin Marine Installer.
Additional Considerations
How many helms are on the boat?
In a multiple helm system, use a power purge system as air can get trapped in the lines of complex systems and not easily hand-bled
What type of fluid is used? Automatic Transmission Fluid (ATF) is not recommended.
ATFs are not designed for hydraulic systems; ATFs are designed for lower-pressure and lower-temperature systems
ATF does not have the viscosity that hydraulic fluid does
ATFs have detergents in them and are often used for cleaning an engine
The color can identify ATF; it's either green or red. Hydraulic fluid should be clear or milky in color
Does the hydraulic fluid have the correct viscosity oxidation stability, and is foaming resistant? A higher operating temperature range will aid in sealing O-rings better, with lubrication, and will perform better in the hydraulic system
What is the steering fluid level at the helm?
- To check this, remove the filler plug on the helm. View into the hole hydraulic fluid should be visible; check the helm manufacturer's recommended level, as these can vary. When adding an Autopilot pump, add additional hydraulic fluid to the system
Where and in what position is the pump mounted?
If mounted in the incorrect position (upside down, vertically with the manifold pointed down), air can become trapped
How many turns does the manufacturer list as hard over? How many turns is it going?
If it's going past the manufacturer-recommended turns, air is in the lines
It should come to a hard stop when performing the turns in the bleeding process; if it's soft or slips, there is either air in the lines or not enough fluid in the reservoir
Was hydraulic fluid reused? It is common to reuse hydraulic fluid; however, if there are issues with bleeding the system, replace the fluid and use a Power Purge (Seastar) or Bubble Buster (UFlex) for bleeding. Both of these systems have a built-in filter in the pump pickup line.