How To Bleed Air From Power Steering System

Just like the brakes, a power steering system must be bled anytime you open the system to replace a PS pump, hose or rack.  After bleeding the PS system on my 2002 Kia Optima, I recommend the following bleeding protocol suggested by GM.

BLEEDING THE POWER STEERING
Aerated fluid will result in noise from the power steering pump. The system should be bled any time a power steering component has been replaced, a fluid line disconnected, or for moaning and groaning noises. To bleed the power steering system, most technicians just fill the reservoir and turn the wheel from lock to lock. This is not the way GM recommends bleeding their system. Prior to bleeding the system, perform a visual inspection to be certain the hoses are not touching any part of the frame or body which can promote a noise. Make certain all hoses are tight, as a loose connection can allow air to enter the system even though fluid will not leak from the connection.

GM’s Recommended Bleeding Procedure:
1) Ignition switch off.
2) Turn steering wheel full left.
3) Fill fluid reservoir to Full Cold level. Leave
cap off.
4) Raise front wheels off ground.
5) With assistant checking fluid level and
condition, turn steering wheel lock to lock
at least 20 times. Engine remains off.
a) On systems with long return lines or
fluid coolers, turn steering wheel lock
to lock at least 40 times.
b) Trapped air may cause fluid to
overflow. Thoroughly clean any
spilled fluid to allow for leak check.
c) Keep fluid level at Full Cold.
6) While turning wheel, check fluid
constantly.
a) No bubbles are allowed.
b) If bubbles appear, recheck connections.
Repeat step 5.
7) Start engine. With engine idling, maintain
fluid level. Reinstall cap.
8) Return wheels to center position. Lower
front wheels to ground.
9) Keep engine running for two minutes.
10) Turn steering wheel in both directions.
Verify:
a) Smooth power assist
b) Noiseless operation
c) Proper fluid level
d) No leaks
e) No bubbles, foam or fluid
discoloration
11) If all conditions apply, procedure is
complete.
12) If any problems remain, see “Special
Conditions.”
Special Conditions:
1) Foam or bubbles in fluid: Fluid must be
completely free of bubbles. In step 5, be alert
to periodic bubbles that could indicate a
loose connection or leaky O-ring seal.
2) Discolored fluid: Fluid which is milky or tan
in color is an indication of aerated fluid.
Switch ignition off. Wait two minutes and
recheck hose connections. Repeat steps 7-
10. If condition still exists, replace O-ring
seals and clamps. Fill system and repeat
bleed procedure.
3) Pump whine or groan: With the engine running,
recheck hoses for possible contact with
frame, body panels or engine. If no contact is
found, allow fluid to cool down and repressurize
system.
If noise persists, remove and replace the power
steering pump. Repeat the bleeding procedure
following the pump replacement.
Following the procedures illustrated can save you
much frustration and your customer money, plus
you fix the problem the first time around. This keeps
the customer happy and coming back for more
service. A happy customer tells his friends about
your shop and that keeps the bays filled.