2000 HONDA CIVIC Cylinder

System Description
Fluid Flow Diagram
The system is a compact rotary-valve-type power steering, connected to the steering gearbox. The fluid pressure is pro-
vided by a vane-type pump which is driven by the engine crank pulley. The amount of fluid and pressure is regulated by
the flow control valve built into the pump. The fluid pressure from the pump is delivered to the valve body unit around the
pinion of the steering gearbox. The valve inside the valve body unit controls the hydraulic pressure and changes the direc-
tion of the flow. The fluid then flows to the power cylinder. where rack thrust is generated. Fluid returning from the power
cylinder flows back to the reservoir, where the fluid is "filtered" and supplied to the pump again.
RESERVOIR
VALVE BOOY UNIT
SUB.VALVE
FLOW CONTROL VALVESTEERING GEARBOX
17-16

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

Pressure Control
Low assist at higher speeds:
WhensteeringresistanceIsIow,suchaswhendrivingathighspeeds,orwhendrivingstraightahead,theinputshaftis
near or in the neutral position, so there is little or no fiow ro any of the power cylinder orifices. Most oI the feed pressure
fromthepumpisbypassedtothereservoir.Becauseofthis,thepressurestaysthesameinbothsidesofthepowercy||n-
der, resulting in low or no asslst
VALVE From PUMP
SECTION A-A
RETURN PASSAGElTo RESERVOIRI
POWER CYLINDER
STEERING GEARBOX
High assist at lower speeds:
When steering resistance is high. such as when driving at low speeds' or when turning the wheel wirh the vehicle
stopped,thedifference|nang|ecreatedbetweentheinputshaftandtheVa|veopensthef|uidpassageononeside,and
c|osesthefluidpassageontheotherside,ateachpairoforifices'Thef|uidpressureincreasesinthesideo|thepower
cy|inder|edbythe|argerf|uidpassage'Thisincreasedpressurepushesontherackpiston,a|lowingthesteeringwhee|to
be turned with light effort. on the other side of the power cylinder, the return passage opens allowing the steering tluid to
returnthroUghtheinputshafttothereservoir'Thef|uidpassagestothepowercy|inderautomatica||ychangeins|ze,
increasing as the steering resrstance increases. In other words, the passages become larger and power assist increases
when the steering effort would normally be high, (for example' when parking or making low speed turns)' and the pas-
sagesbecomesma||erandpowerassistdecreaseswhenthesteeringeffortwou|dnorma||ybe|ow,(forexamp|e,when
driving at high speeds or straight ahead).
FLUIO PASSAGE TO
POWER CYLINDER
/t=\\a!-4,))
=YjJ
RESERVOIR
SECTION A-A
l'
{High fluid Pressure}

I
AbnormalDeformed
Faulty cylinder lines
Adiustment OK
Faulty valve body unit
Normal
IICompair the steering to another alike
vehicle.
/
Check the force required to turn
the wheel (see Page 17 30i
Start the engine and measure the
force required to turn the wheel
to the right and left. Difference of
the lorce required to turn the
wheel to the right and to the Ieft
should be 2.9 N 10 3 kgf, 0.7 lbf)
or below.
Check for bent rack shaft
Check rack guide adiustment (see
page 17-33).
(cont'd)
17 -23
1,,

Troubleshooting
General Troubleshooting (cont'd)
Assist (excessively light steering) athigh speed.
Shock or vibration when wheel isturned to {ull lock.
Steering wheelwill not returnsmoothly.
lf the problem is not corrected byadiusting the rack guide, adjustthe front wheel alignment lseesection 181.
Check the rack guide for properadiustment (see page 17 33).
Check the rack guide for properadjustment (see page 17-33).
Rack guide is adjusted properly.
lfthe problem is not corrected byadjusting the rack guide, replacethe gearbox.Check the belt for slippage andaolust as necessary {see page11 32).
A and B cylinder lines are nor-mal, check wheel alignment (seesection 18).
Wheel alignment is abnormal,adjust as needed.
Wheel alignment is normal.Check the steering wheel opera-tion and power assist check {seepage lT-30).
It the measurements are out ofspecifications, adjust the ra ckguide.
lf the problem is not corrected byadjusting the rack guide, replacethe gearbox.
17-24

Troubleshooting
Fluid Leaks
Check the gearbox assembly for oil leaks carefully. Oil can leak out of various points. depending on location of thefaulty oil seals/seal rings. Check the following before removing the gearbox from the frame_
Steering GearboxLeaking from the oil seal on thetop of the valve housing.Replace the valve oil seal fromthe valve housing.
Leaking from cylinder end intoleft tie rod boot.Replace the valve oil seal tromthe pinion shaft.
Replace the cylinder end seal onthe gear housing side.
Leaking lrom cylinder end intoright tie-rod boot.Replace the cylinder end seal onthe cylinder end side.
Leaking lrom the shaft upper endsectron or pin engagement sec,tion ol the pinion shaft.Replace the valve body unit.
Tighten the connector. lf it's stillleakinO, replace the Iine, cylinderor valve housing unit.
Leaking from cylinder line A or Bconnections {at tlare nut}.
Leaking caused by a damagedcylinde.line A or B.Replace cvljnder line A or B.
Leaking from feed line and returnline ioint fitting on the valve bodyunit (at flare nut).
Tighten the connector. ll it's stillleaking, replace the line,,oint fit,ting or valv6 housing.
17-2a

Power Steering Hoses, Lines
Fluid Leakage Inspection
HOSES and LINES
. Inspect hoses for damage, leaks, interference or
twisting.
. Inspect tluid lines for damage, rusting and leakage.
. Inspect for leaks at hose and line joints and connec-
tions.
POWER STEERINGswtTcH12 N.m {1.2 kgt.m,9lbt.ft}
CYLINDER HOUSING-to.CYLINDER LINES28 N.m (2.7 kgf.m, 20 lbf.ft)
VALVE BODY UNIT-to-CYLINDER LINES'17 N.m {1.712 tbl.ftl
VALVE BODY UNIT-Io-FEED/RETURN LINES
Feed line: 14 x '1.5 mm llare nut
37 N.m {3.8 kgJ.m, 27 lbf'tt)
Return Line Joint 16 x 1.5 mm flare nut
28 N m 12.7 kgf.m,20 lbtft)
HOSE CLAMP:
. Position the hose clamps at the points indicated (b) in
the drawing above.
. Slide the hose over the line until it contacts the stop.
8()07Check for leaks.
OUTLET HOSE11 N.m
G€AR8OX and VALVE BODY UNITCheck for leaks at the mating surfaceand flare nut connections,
tbt(Double Ring Typei
CAUTION: Check all clamps for deterioration or delor-
mation; replace with the clamps new ones il necessary.
(1.1 kgf.m,8
PUMP ASSEMBLYCheck for leaks at the pump
seal, inlet and outlet fiftings.
Replacement
NOTE:
. Connect each hose to the corresponding pipe securely
until it contacts the stop on the line. Install the clamp
or adiustable clamp at the specified distance from the
hose end as shown.
. Add the power steering fluid to the specified level on
the reservoir and check for leaks.
ADJUSTABLE HOSE CLAMP:
. Position the adiustable hose clamps at the points
indicated (a) in the drawing above.
. Slide the hose over the line until it contacts the stop.
2.5 - 5.5 mm{0.01 - 0.22 in)2.0 - 4.0 mm(0.08 - 0.16 in)
2.5 - 5.5 mm(0.01- 0.22 in)1.,
17-39

Steering Gearbox
Removal {cont'dl
Loosen the 14 mm flare nut and disconnect the feed
line.
Loosen the adjustable hose clamp and disconnect
the return hose.
Loosen the 16 mm flare nut and remove the return
hose joint trom the valve body unit.
CAUTION: After disconnecting lhe hos6 and lin6.
plug or seal the hose and line with a pioca ol tapa
or equivalent to prevenl foreign matorials trom
entsring the valve body unit.
NOTE: Do not loosen the cvlinder line A and
between the valve body unit and cylinder.
ADJUSTABLE HOSECLAMP
Remove the stiffener Dlate.
NOTE: Some stiffener plate attaching bolts are also
used as gearbox mounting bolts. The gearbox will
tilt to side when these bolts are removed.
13.
14.
t9.
16.
17-48,
17. Remove the mounting brackets.
Pull the steering gearbox all the way down to clear
the pinion shaft from the bulkhead. then remove the
pinion shaft grommet.
Move the steering gesrbox to right so the left rack
end clears the rear beam, then tilt the left side down
to remove it from the vehicle,
CAUTION: Be careful not io bend or damage the
fagd ling and cylindsr lin99 whgn rgmoving thg
ggarbox,
18.
STEERING GEANEOX