Hydraulic Fluid Level; Setting Fluid Level; Maintaining Fluid Level; System Check - Mercury MerCruiser Service Manual

5. Helm and hose identification.

Hydraulic Fluid Level

Failure to fill the system properly can damage steering components, causing serious injury or death from loss of boat control.
Completely retract the cylinder rod before checking or adding hydraulic fluid.

Setting Fluid Level

The system must be filled and purged as outlined previously before setting the fluid level.
1. Ensure that the cylinder rod is fully retracted.
2. With the filler tube screwed into the helm filler plug hole, fill the tube approximately half full of air‑free hydraulic fluid.
3. Open the starboard bleeder valve and slowly turn the steering wheel clockwise until the fluid level in the filler tube is at the
top of the plastic filler fitting. Continue turning steering wheel clockwise ¼ turn more, and then stop. Close the bleeder
valve.
4. Remove the filler tube. The fluid level should be at the bottom of filler hole. Install the vent/fill plug.

Maintaining Fluid Level

To maintain proper fluid level, observe the following:
• Do not allow the fluid level to drop more than 6 mm (¼ in.) below the bottom of the filler hole.
• Check the fluid level periodically.

System Check

After filling, purging, and setting the fluid level the system must be checked for proper connections, possible leaks, and
complete purging of air.
IMPORTANT: In the following procedure, turn the wheel with enough force to exceed the pressure relief valve in the helm. This
action should not harm the helm or the system.
1. Turn the steering wheel (any wheel on a multi‑steering station) very hard to port to pressurize the system.
90-8M0099748 eng DECEMBER 2015
a - Thin wrench
b - Helm hex fitting "P & T"
c - Helm hex fitting "R & L"
d - Hydraulic hose hex fitting "P & T"
e - Hydraulic hose hex fitting "R STAR & L PORT"
42888
WARNING
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© 2016 Mercury Marine
Compact Hydraulic Steering
Page 8B-9