From W-H ➥ Installation | WH Autopilots, Inc.
Filling and Bleeding the Hydraulic System
Install two plastic hoses on the two bleed tees (barbed fittings), located on each end of the hydraulic cylinder. Place the hose ends into a small clean pail of one or two quart size. Fill the container about half full of thin hydraulic oil.
Use any hydraulic oil, which meets MIL-H-5606 specifications. These oils are thinner than automatic transmission
fluid and most other commonly used hydraulic oil. Type “A” automatic transmission
fluid can be used but will slightly increase your hand steering
Open both bleed tees by turning the nut 1 turn counter clockwise and pulling the nipple out to the open position. Turn the bypass valve to the AP ON position. (Pull the Tee handle up.) Move the steering wheel
back and forth from one extreme to the other, adding oil to the pail and reservoir as it runs out. Continue moving the rudder
from one extreme to the other until no more air bubbles appear. Do not allow air to be sucked into the cylinder from the pail or reservoir. Now center the rudder
with the steering wheel
and close one of the bleed valves (leave one open).
Run the autopilot
in standby mode by holding down one dodge button. Push the dodge button that seems to drain the reservoir the most rapidly. Add oil to the reservoir as needed. Now open the bypass valve (push the tee handle down to put the system in the manual steering mode).
Continue to run the motor
until solid oil (no air) comes out of the bleed hose. Again close the bypass valve (tee handle pulled up) and repeat the above procedure closing the open bleed tee and opening the other one. If the pump will not suck oil from the reservoir (this may happen with extra long lines) then oil must be fed directly into one of the main lines on the pump.
Now, with the autopilot turned off (electrically with the rotary mode switch), close the bypass valve (tee handle pulled up), close both bleed tees. Try moving the steering wheel with about 40 or 50 lb. of force. Watch the rod in the cylinder. It should not move more than 1/8”. If it moves further, there is still air in the cylinder and the above procedures must be repeated, or continue to step 8. If there is still a problem with air in the system, try the following: Remove the linkage from RAT, (rudder angle transmitter) and center the RAT arm (align the red marks).
Now move the rudder to its extreme position in one direction (using the steering wheel.) And repeat procedure #3 above. Now close that bleed valve and open the other one and repeat the procedure again. Move the rudder to the other extreme position and repeat the procedure. Close the bypass valve (tee handle pulled up), place the autopilot in STANDBY MODE and make sure both bleed tees are closed. Press the port and then the starboard dodge buttons. Check to see that the rudder will move the boat to port when the red, left side dodge button is pressed.