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Bleeding the Hydraulic Steering System
Bleeding the Hydraulic Steering System
Bleed the hydraulic system (Simple hydraulic system)
Connect the port and starboard bleed valves on the steering cylinder with a section of 1/4" fuel hose and two hose clamps
Open the bleed valves until they are reasonably loose - almost coming off
Turn the helm in one direction until the rudder reaches the stop. Keep turning for a few minutes longer
Check the fluid level on the helm reservoir while turning the helm. Add fluid as needed. As air bubbles cycle out of the hoses, the hydraulic system will make noises, and the fluid level will drop
Continue to turn until there is no noise coming from the helm, and the turns feel smooth for many seconds
Bleed the pump
Air goes to the highest point. If the hoses from the pump face downward, then this will be a lot harder.
If the autopilot pump is a SmartPump open the bleed valve on it (black knob counter-clockwise turning)
Run the pump in one direction using Verify Steering Direction. Let it go for 30 seconds
GHC (Garmin Helm Control) Menu > Setup > Dealer Autopilot Setup > Steering System Setup > Verify Steering Direction or Steering Dir
Chartplotter Settings > My Vessel > Autopilot > Installation Setup> Steering System Setup > Verify Steering Direction or Steering Dir
If the reservoir hose is letting fluid flow freely to the pump, then this should do it
Vent the reservoir by leaving the cap off unless the autopilot pump is part of a pressurized Hynautic system. Do not vent in that case
Ensure the reservoir is uphill to the pump
Ensure the reservoir hose doesn't have loops, u-bends, kinks, or is twisted. Avoid things that would block flow
If in doubt, this can be easily checked by disconnecting the reservoir hose at the pump and checking for fluid flowing easily. If it doesn't flow freely, then inspect the system looking for a blockage
Close off bleed valve on SmartPump
Complete steps 3-5 again
When finished, tighten the bleed valves back up. Do not overtighten; the bleed valves should be snug, not tight
More complex hydraulic systems (multi-helm, hoses that run up-down-up inside the boat that trap air, etc.) may need a power purge system to get the air out.
Test the System
After bleeding, test by turning the helm all the way to port and starboard hard over. It should feel solid. If it is not firm, check the reservoir level, add fluid as needed, and test again.
If still mushy, then it may require careful bleeding. Also, test the pump by running the autopilot to both the port side and starboard side hard over. It should stall promptly and come off the stop without a lot of trouble. The 1.2 and 2.0 pumps will retry the hard stop twice, but those should be a much quieter buzzing noise that repeats twice. If the helm wheel is turning very slowly on its own while the pump is running, especially at the stop, then the helm check valve/s may be stuck open and flow from the pump is back driving the helm; fix and try again.
Things that can go wrong
The fuel hose connecting the bleed valves can blow off and spray a little fluid. If this happens, it's typically one of the bleed valves not being loose enough. Reconnect and loosen
Overtightened bleed valves easily strip the threads. Purchase replacement brass fittings
The system was not fully bled or was not bled well. Turn the helm in either direction to the stop. If it's soft, there is still air in the lines. The autopilot may have a hard time steering the rudder off of one stop or another
The helm/reservoir at the highest elevation must have a ventilation hole to allow proper flow. Usually, the ventilation is a tiny hole drilled into the screw-on cap for the filling hole. If a ventilation hole is not present, it will interfere with bleeding and exhibit behaviors similar to air in the system