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Tips for Bleeding the Hydraulic System
When performing any changes to a hydraulic system, such as installing an autopilot pump, the system must be bled. Check with the helm manufacturers' owner’s manual for brand specific directions on bleeding the steering hydraulics on the vessel.
Make sure the proper amount of hydraulic fluid is added when installing the autopilot
The autopilot will be viewed as 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 with new hydraulic fluid
If reusing hydraulic fluid and there are issues with bleeding, try using a fine mesh filter such as those for gasoline. A Power Purge (Seastar) or the Bubble Buster (Uflex) systems have 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 there is air in the lines; consider using a power purge to bleed the system
Several steering systems / helms can be bled easily by hand. Whereas more complex systems may require the use of additional equipment, such as a power purge. If you are not comfortable performing such tasks, seek a certified Garmin Marine Installer.
Additional Considerations
Are you getting a "Pump Stall" error?
If a "Pump Stall" error doesn't appear promptly upon driving to the starboard or port stops, there is still air in the lines
Air or dirt in the lines can cause it to fail bleeding properly
Was the Helm previously working?
How many helms are on the boat?
In a multiple helm system, it is recommended to use a power purge system as air can get trapped in the lines of complex systems that is not easily hand bled
What type of fluid is being used? Automatic Transmission Fluid (ATF) is not recommended
ATF's aren’t designed for hydraulic systems; ATF's are designed for lower pressure/temperature systems
ATF does not have the viscosity that hydraulic fluid does
ATF's have detergents in them and are often used for cleaning an engine.
ATF can be identified by the color; it's either green or red. Hydraulic fluid should be clear or milky in color
Hydraulic Fluid has the correct viscosity, oxidation stability and is foaming resistant. 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, additional hydraulic fluid will need to be added to the system
Where and what position is the pump mounted at?
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 manufacturers recommended turns, there is air 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
Is the Helm Hydraulic system a new install? If yes, was steering system fully bled per manufacturer’s directions?
This is to verify that there wasn’t an issue with the hydraulic system prior to the installation of the autopilot system
When adding the Autopilot pump, how much hydraulic fluid was used?
Consult the manufacturers helm and cylinder information and check manufacturers specifications for amounts
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
Basic Bleeding Procedure
Start at the helm closest to the steering cylinder (multi-helm only)
Remove fill plug and install hose fitting and hoses
Wrap an oil absorb pad around the helm to prevent leaks
Make sure any other helms in the system have non vented plugs installed or leaks will occur
Connect hoses to steering cylinder and loosen the bleed fittings one turn
Connect 12V power
Switch on purge, check for leaks
Turn the steering wheel clockwise until steering ram is fully extended, continue turning slowly for at least 30 seconds or until no bubbles are visible in the cylinder hose
Repeat in counterclockwise as above
If there are addition helm stations, repeat the above steps as necessary
Set autopilot to Dealer Mode* and use 'Verify Steering Direction' to operate the pump for at least 30 seconds in each direction
Disconnect hoses, power, etc. Tighten bleed fittings, verify fluid level in helm and install plug
Operate helm in both directions and check for smoothness and positive end stops
Operate autopilot and verify rudder moves smoothly
*To put the autopilot into dealer mode follow these steps
From the GHC 20:
Press the Menu Button
Select Set Up
Select System
Select System Information
Press and hold the center soft key until Dealer Mode appears above it
From the GHC 50:
The GHC 50 has Autopilot Setup and 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