Chrysler neon 1997 Service Manual page 1358

PL
DESCRIPTION AND OPERATION (Continued)
Rectangular pumping vanes in the shaft driven
rotor, move power steering fluid from the intake to
the cam ring pressure cavities of the power steering
pump. As the rotor begins to turn, centrifugal force
throws the vanes against the inside surface of the
cam ring to pickup residual oil. This oil is then forced
into the high pressure area. As more oil is picked up
by the vanes, the additional oil is forced into the cav-
ities of the thrust plate through two crossover holes
in the cam ring and pressure plate. The crossover
holes empty into the high pressure area between the
pressure plate and the housing end cover.
As the high pressure area is filled, oil flows under
the vanes in the rotor slots, forcing the vanes to fol-
low the inside surface of the cam ring. As the vanes
reach the restricted area of the cam ring, oil is forced
out from between the vanes. When excess oil flow is
generated during high-speed operation, a regulated
amount of oil returns to the pump intake side
through a flow control valve. The flow control valve
reduces the power required to drive the pump and
holds down temperature build-up.
When steering conditions exceed maximum pres-
sure requirements, such as when the wheels are
turned against the stops. The pressure built up in
the steering gear exerts pressure on the spring end of
the flow control valve. The high pressure lifts the
relief valve ball from its seat and allows oil to flow
through a trigger orifice located in the outlet fitting.
This reduces pressure on the spring end of the flow
control valve which then opens and allows the oil to
return to the intake side of the pump. This action
limits maximum pressure output of the pump to a
safe level.
Under normal power steering pump operating con-
ditions, pressure requirements of the pump are below
maximum, causing the pressure relief valve to
remain closed.
DIAGNOSIS AND TESTING
POWER STEERING SYSTEM TEST PROCEDURE
The following procedure can be used to test the
operation of the power steering system on the vehi-
cle. This test will provide the flow rate of the power
steering pump along with the maximum relief pres-
sure. This test is to be performed any time a power
steering system problem is present to determine if
the power steering pump or power steering gear is
not functioning properly. The following pressure and
flow test is performed using Pressure/Flow Tester,
Special Tool 6815 (Fig. 2).
TO TO PRESSURE HOSE STEERINGPUMP STEERING GEAR POWER POWER SPECIAL TOOL 6815
Fig. 2 Power Steering Pump Flow/Pressure Tester
POWER STEERING PUMP FLOW AND
PRESSURE TEST PROCEDURE
(1) Check power steering pump drive belt tension
and adjust as necessary.
(2) Disconnect power steering fluid pressure hose,
at power steering pump. Use a container for dripping
fluid.
(3) Connect Pressure Gauge, Special Tool from kit
6815 (Fig. 3) to both hoses using adapter fittings.
Connect spare pressure hose, to power steering pump
pressure hose banjo fitting.
Fig. 3 Power Steering Pump Flow/Pressure Tester
Connected To Power Steering Pump
(4) Completely open valve on Special Tool 6815
(Fig. 3).
(5) Start engine and let idle long enough to circu-
late power steering fluid through flow/pressure test
and get air out of fluid. Then shut off engine.
(6) Check power steering fluid level, and add fluid
as necessary. Start engine again and let idle.
(7) Pressure gauge should read below 862 kPa
(125 psi), if above, inspect the hoses for restrictions
and repair as necessary. The initial pressure reading
ADAPTER POWER TINGS FIT- SPECIAL ING PUMP STEER- TOOL 6815
STEERING 19 - 11