1999 HONDA CIVIC ac system

System Description
Steering Pump (cont'dl
The flow control valve and sub-valve in the pump per-
forms the following steps @ through @ to control the
flow of fluid, that is to increase the discharge volume
when engine speed is low, and to decrease it when the
engine speed increases. The assistance thrust of the
steering gearbox changes in compliance with the
change in the discharge volume.
When the engine starts, fluid discharged from the
discharge port starts to flow through oil passage A,
the fixed orifice and the variable orifice to the steer-
ing gearbox. When the engine speed is extremely
low, the return port is closed by the flow control
Fluid pressure discharged from the discharge port
is applied to the top of the sub-valve, and the fluid
pressure that passed through oil passage A is applied
to the bottom of the sub-valve. When this happens,
the pressure difference between the ends of oil pas-
sage A, which is caused by the resistance oil passage
A when the fluid flows through the passage. is
applied to the sub-valve, However, the pressure dif-
ference applied to the sub-valve. that is the force
that pushes the sub-valve down, is too small to
overcome the spring force, and the variable orifice is
fully open when the engine speed is extremely low.
Because the fluid volume flowing through the fixed
orifice and variable orifice increases, a pressure dif-
terence is created between the ends of these ori-
fices, and it increases in proportion to the engine
speed. As the fluid pressure that passed the fixed
orifice and variable orifice is directed to the bottom
of the flow control valve. a pressure difference is
created between the top and bottom of the valve,
which pushes down the flow control valve and
opens the return port. As a result, pan of the fluid
discharged from the discharge port feturns to the
pump suction port, keeping the discharge volume
constant.
In this condition, the sub-valve does not move. and
the variable orifice stays fully open.
lo
trrtrrlo3
J
o
PUMP R.P.M.
To STEERING GEARBOXSUB.VALVE
To STEEnING GEARBOX
FLOW CURVE
!rs+/f/ffih\
o,,-i^"l^tKzYt)91y ul3Yl
FLOW CONTNOL VALVE
su8-vALvE
ORIFICE
ToP
17-18
FLOW CONTROL VALVE

t
To STEERING GEARBOX
To STEERING GEAREOx
@ The fluid volume that flows thorough oil passage A
and the pressure djfference applied to the sub-valve
increase in proportion to the engine speed. The
sub-valve lowers overcoming the spring force, and
it stans to close the variable orifice to regulate the
discharge volume, When this happens, the fluid vol-
ume flowing to the steering gearbox decreases as
the engine speed increases. At the same time, the
flow control valve continues to control the fluid vol-
ume to the return Port,
@ As the engine speed increases funher, the pressure
difference at the sub-valve increases further as well.
The sub-valve then closes the variable orifice com-
pletely, regulating the discharge volume further.
When this happens, the fluid volume discharged
from the pump to the steering gearbox is regulated
and maintained at a given level until the engine
speed reaches the high speed range The flow con-
trol valve functions continues to control the fluid
volume to the return Port.
Pressure Relief
Pressure at the discharge side of the fixed orifice is
directed to the bottom of the flow control valve. When
the pressure builds up, the relief valve in the flow con-
trol valve opens to release the pressure at the bottom of
the valve. This allows the flow control valve to be
pushed back by the pressure difference, and the fluid
volume to the pump return port increases.
As explained above. the system keeps the pump dis-
charge pressure (relief pressure) from exceeding the
given level by controlling the volume of the fluid to the
pump relurn pon,
1.,DAMPING ORIFICE{Docreases excessiv€vibration in the valv6.)
17-19
)
RELIEF VALVE {Opan)
SUB.VALVE
FLOW CONTROL VALVE
/F ft>..\
'-€/K\A/A
o'.'to"5lo'#2"n af11\D7
FLOW CONTROL VALVE

System Description
Steering Gearbox
The rack-and-pinion type steering gearbox has a valve body unit incorporated with the pinion to control the steering fluidpressure. Steering fluid from the pump is regulated by a rotary valve in the valve body unit and is sent through the cylin,der line to the power cylinder, where hydraulic pressure is applied. The steering fluid in the other side of the power cylin,der returns through the cylinder line and valve body unit to the reservoii.
VALVE EODY UNIT
CYLINDER LINE
To RESERVOm +-From PUMP -;
POWER CYLINDER
Valve Body Unit
Inside the valve body unit is the valve, which is coaxial with the pinion shaft, and controls the steering fluid pressure. Thevalve housing is connected with the fluid line from the pump, the return line to the reservoir, and the two cylinder linesfrom the respective power cylinder. The pinion shaft is double - structured with the input shaft connected to the piniongear, both of which are interconnected with the torsion bar.
The pin inserted in the valve and the pinion shaft groove engage; this allows the pinion shaft to rotate together with thevalve. Because of this construction, the difference in angle in the circumferential direction between the input shaft and thevalve becomes larger according to the torsional strength of the pinion or steering resistance. However, maximum torsionbetween the shafts is regulated by the engaged splines of the shafts at the pin engagement section to hold the torsion barwithin the set value,
This allows the steering system to function as an ordinary rack-and-pinion type steering if the steering fluid is not pressur-
ized because of a faulty pump,
VALVE
Difforence in angle botwoon theinput shaft and pinion shsft
PINION SHAFT
lo
INPUT SHAFT
-l
a
17-20
INPUT SHAFT

/
Uneven or rough steering
Steering wheel kicks back
during wide t!rns.
ll,
)
Adjust the rac* guide (see page 17-3).
lf the problem is not corrected bY
adjusting the rack guide, replace
the gearbox.
Adiust the belt tension. Feplace the
belt, il necessary (see Page 17 32).
lfthe engine stalls when the wheel
is turned while car is stopped or
moving at low speed, adjust the
idle spe€d (see section 11)
ldle speed low or erratic.
Check power sleering fluid level lf
the level is excessively low, check
lor leaks in the system. Add lluid
to the specified level.
Air in reservoir, or check Powersteering Iluid level.
lf ltuid level is OK, check O-rings
and seals on both ends of thepump inlet hose, and the P/Spump housing mating surfaces
and the pumP shaft oil seal for
suction leaks. RePlace Parts as
nocessary.
Adjust the belt tension (see Page17 32)or replace belt.Pump belt sliPPing on PLrlleY(pump stops momentarilY)
Check if pump press{rre is normal
and the gauge needle travel is 500
kPa (5 kgl/cm?, 7l Psi) or less.
Chock the flow control valve if the
needle travel exceeds 500 kPa (5
kgflcm', 71 Psi). l{ the flow control
valve is normal, replace the PumPas an assemoly.
Install the power steering pressure
gauge, Close the Pressure contrcl
valve fully and m6ssure the PumPpressure {s€e page 17-34}.
17 -25,

IRack Guide Adjustment
NOTE: Perform rack guide adjustment with the wheels
in the straight ahead Position.
1. Loosen the rack guide screw locknut with the
cialtool.
'96 - '97 models:
Loosen the rack guide screw
'98 - '00 models:
Remove the rack guide screw and remove the old
sealant off of the threaded section.
Apply new sealant all around the threads. Loosely
installthe rack guide screw
Tighten the rack guide screw to 25 N'm (2.5 kgf'm.
18 lbf.ft), then loosen it.
Retighten the rack guide screw to 3 9 N'm (0.4 kgim,
2.9 lbf.ft), then back it off to specified angle.
Specified Return Angle: 20" max.
Tighten the locknut while holding the rack guide
screw.
Check for tight or loose steering through the com-
plete turning travel.
Perform following insPections:
. Steering operation (see page 17-30).
. Power assist with vehicle parked.
4.
LOCKNUT WRENCH, 40 mm
lr
17-33
Fluid Replacement
Check the reservoir at regular intervals, and add fluid as
necessary.
CAUTION: Always us€ Genuine Honda Power Stearing
Fluid-V or S. Using any other type of power sto€ring
tluid or automatic transmission lluid can cause
increased wear and poor steering in cold weathor.
SYSTEM CAPACITY:
0.85 liter 10.90 US' qt,0.75 lmp'qt)
at disassembly
RESERVOIR CAPACITY:
0.4 liter (0.42 US. qt, 0.35 lmP.qt)
LEVEL LINE
LOWER LEVEL LINE
1. Raise the reservoir, then disconnect the return nose.
2. Connect a hose of suitable diameter to the discon-
nected return hose, and put the hose end in a suit-
able container.
CAUTION: Take care not to spill tho fluid on the
body and parts. Wipe off any spill€d fluid at oncs'
3. Start the engine, let it run at idle, and turn the steer-
ing wheel from lock-to-lock several times When
fluid stops running out of the hose, shut off the
engine, Discard the fluid.
4. Reinstall the return hose on the reservoir'
5. Fill the reservoir to the upper level line.
6. Start the engine and run it at fast idle, then turn the
steering trom lock-to-lock several times to bleed air
trom the system.
7. Recheck the fluid level and add some it necessary.
CAUTION: Do not fill the reservoir beYond the
upper l€vel line.
HOSE

Steering Wheel
l,/
Removal
SRS components are located in this area Review the
SRS component locations, precautions, and procedures
in the SRS section (24) before performing repairs or ser-
vice.
NOTE: Before removing the steering wheel. align the
front wheels straight ahead.
1. Remove the driver's airbag assembly from the
steering wheel (see section 24)
2. Disconnect the horn connector and cruise control
switches connector.
CRUISESWITCHES CONNECTOR
3. Remove the steering wheel nut
STEERING WHEEL NUT
Replace.
Remove the steering wheel by rocking it slightly from
side-to-side as you pull steadily with both hands.
ag N.m {5.0 kgt rn, 36lbfft)
1.,
17-35
lnstallation
CAUTION: Do not tap on the steering wheel or steering
column shaft when installing the stsering wheel.
NOTE: Before installing the steering wheel, align the
front wheels straight ahead.
1. Before installing the steering wheel, center the
cable reel, Do this by first rotating the cable reel
clockwise until it stops. Then rotate it counterclock-
wise approximately two turns The arrow mark on
the cable reel label should points straight up.
Install the steering wheel with the steering wheel
nut.
NOTE: Be sure the steering wheel shaft engages
the cable reel and canceling sleeve.
Attach the cruise control switches connector io the
steering wheel cliP,
Connect the horn connector.
Install the driver's airbag assembly, and confirm
proper system operation (see section 24).
Check the horn and cruise control switches for
proper operatrons.
CAELE REEL

Disassembly
CAUTION: The power steering components are made of aluminum. Avoid damaging the components during assembly.
NOTE:
. Ctean the disassembled parts with a solvent, and dry them with compressed air. Do not dip the rubber parts in a sol-
vent.
. Alwavs replace the O-rings and rubber seals with new ones before assembly.
. Apply recommended power steering fluid to the parts indicated in the assembly procedures'
. Do not allow dust, dirt, or other foreign materials to enter the power steering system.
. Replace the pump as an assembly ifthe parts indicated with asterisk (*) are worn or damaged'
FLANGE BOLTS20 N.m {2.0 kgf.m,14 rbf ft)
5 mm ROLLER
4.5 mm ROLLER
*OUTER SIOE PLATE
*SUB-VALVE
.PUMP NOTOR
}SIDE PLATE
l,/SNAP RING13 x 1.9 mm O-RINGReplace.
15.2 x 2.4 mm O-RINGReplace.
INLET JOINT
51 x 2.4 mm O-RINGReplace.
FLANGE BOLTS11 N m 11.1 kgf.m,8 rbf.ftl
PUMP SEALReplace.
PUMP SEAL SPAC€R
.PUMP DRIVE SHAFT
BALL BEARINGlnspection and RePlacement,see page 17-43
10 mm CIRCLIP
*FLOW CONTROI- VALVEInspection and Overhaul,se[ pase tt.tz g
4 --{;'rX!;'seatuc/ $
mm O-RINGPULLEY NUT6il N.m {6.5 kgf.m,47 tbf.frlFI-OW CONTROL VALV€ CAP49 N.m {5.0 kgt m,36 rb{.ft)
(cont'd)
17-41
J

)Reassembly
NOTE:
. clean the disassembled parts wrth a solvent, and dry them with compressed air. Do not dip the rubber parts in a sol-
vent.
. Always replace the O-rings and rubber seals with new ones before assembly'
. Apply the recommended power steering fluid to the parts+ndicated in the assembly procedures'
o Do not a||ow dust, dirt, or other foreign materials to enter the power steering system.
a Use the appropriate special tools where necessary'
FLANGE BOLTS20 N.m (2.0 kgt'm, 14lbf ftl
CYLINDER LINE B
VALVE HOUSINGFLARE NUTS
28 N.m (2.7 ksf m,20 lbf ftl
VALVE OIL SEAL
Replace.
CYLINDER END SEAL
Replace.
f itllTllli".",'r'o,.n,ft
''*^'*-1$*€-/s6-,,mode,3:
EUSHINGReplace 'P'\-- BEARING
SLEEVE SEAL RINGS ..-------...... SS
.----
",a"a,,
*---
--,
Replace. lss-, Replace.
Xll,Y5"l'.
"o. --r...- gY------..r.u,
,-f-..-S: _ ,96 _,9? models:
--€l€--------=- ircriip'ii.rt'-l./BACKUPReplace.
I,
wAvE wAsHER d
-.-.-r_ i"pru"".
CYLINDER HOUSING // -\-
, AJ - O.RING
/ ,S-'..- ReDtace.
_ j GEAR HouslNG l.g --'\-
\- t F
tonsrnrr
.,_- s
- 'oo ,,iod"t., -s-'--------- vALvE SEAL R'NG
S_.<---,tj- 97 models onlY:
CYLINDER END SEAL
)@OOD m n"prac".
/'\N,."._nrNG I '98 - 'oo - RACK GUIDE
models:
:scREw I
O.RINGReplace..98 - '00 models:
CYLINDER END69 N.m {?.0 kgt'm,51 lbl'ft)
(cont'd)
17-55
CYLINDER LINE A
tJ