1999 HONDA CR-V low oil pressure

Description
Rear Differential
Outline
The Real-time 4WD-Dual Pump System model has a hydraulic clutch and a differential mechanism in the rear differential
assembly. Under normal conditions, the vehicle is driven by the front wheels. However, depending on to the driving force
of the front wheels and the road conditions. the system instantly transmits appropriate driving force to the rear wheels
without requiring the driver to switch between 2WD (tront wheel drive) and 4WD (four wheel drive). The switching mecha-
nism between 2WD and 4WD is integrated into the rear differential assembly to make the system light and compact.
ln addition, the dual-pump system switches off the rear-wheel-drive force when braking in a forward gear. This allows the
braking system to work properly on models equipped with an Anti-lock Braking System (ABS).
Construction
The rear differential assembly consists of the torque control differential case assembly and the rear differential carrier
assembly. The torque control differential case assembly consists of the differential clutch assembly, the companion
flange, and the oil pump body assembly. The rear differential carrier assembly consists of the differential mechanism. The
differential drive and driven gears are hypoid gears.
The oil pump body assembly consists of the front oil pump, the rear oil pump, the hydraulic control mechanism, and the
clutch piston. The clutch piston has a disc spring that constantly provides the differential clutch assembly with a preset
torque to Drevent abnormal sound.
The clutch guide in the differential clutch assembly is connected to the propeller shaft via the companion flange, and it
receives the driving force lrom the transfer assembly. The clutch guide rotates the clutch plate and the front oil pump in
the oil pump body.
The clutch hub in the differential clutch assembly has a clutch disc that is splined with the hypoid drive pinion gear. The
hypoid drive gear drives the rear oil pump.
The front and rear oil pumps are trochoidal pumps. The rear oil pump capacity is 2.5 percent larger that the front oil pump
to handle the rotation difference between the front and rear wheels caused by worn front tires and tight corner braking.
The oil pumps are designed so the fluid intake works as a fluid discharge when the oil pumps rotate in reverse. Genuine
Honda CVT fluid is used instead of differential fluid.
Operation
When there is a difference in rotation speed between the front wheels (clutch guide) and rear wheels (hypoid driven gear),
hydraulic pressure from the front and rear oil pumps engages the differential clutch, and drive force from the transler
assembly is applied to the rear wheels.
The hydraulic pressure control mechanism in the oil pump body selects 4WD mode when the vehicle is started abruptly,
or when accelerating in a forward or reverse gear (causing rotation difference between the front and rear wheels). or
when braking in reverse gear {when decelerating). lt switches to 2WD mode when the vehicle is driven at a constant speed
in forwar! or reverse gear (when there is no rotation difference between the front and rear wheels), or when braking in a
fo rwa rd gear (when decelerating).
To protect the system, the differential clutch assembly is lubricated by hydraulic pressure generated by the oil pumps in
both 4WD and 2WD modes. Also, the thermal switch relieves the hydraulic pressure on the clutch piston and cancels 4WD
mode if the temDerature of the differential fluid rises above normal.
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Description
Hydraulic Flow
Forward Start and Acceleration l4WD)During a forward start and forward acceleration, the dual pump system can engage four wheel drive.lf the front wheels spin faster than the rear wheels, the front oil pump spins faster than the rear oil pump. The front pump
draws fluid through check valve B and discharges it. Some of the discharged fluid is drawn in the by the rear oil pump.The remaining fluid will pass through check valve E into the clutch piston. There, hydraulic pressure is regulated by twoorifices.
The regulated hydraulic pressure at the clutch piston pushes the plates and discs of the clutch together to form a connec-tion. The engaged clutch then passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRrFtcEsFRONT OIL PUMPREAR OIL PUMP
Forward Driving at Constant Speed lzWD)When driving forward at a constant speed (cruising), the dual pump system functions in two wheel drive mode.The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same.Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. Becausethere is no pressure built up at the clutch piston, the clutch does not engage, and the vehicle remains in 2WD (front wheeldrive).
FRONT OIL PUMP
15-6
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Description
Hydraulic Flow (cont'dl
Reverse Driving at Constant Speed l2WD)when driving in reverse at a constant speed, the dual pump system functions in two wheel drive mode.The rotation speed of the front and rear wheels is the same, so the speed of the front and rear pumps is also the same,Fluid discharged by the front oil pump is drawn in by the rear oil pump and is circulated through the system. But, becausethe there is a difference in the capacity between the two pumps, fluid flows through check valve E, and then through ori-Iices. This fluid lubricates and cools the clutch assembly and bearings.ls this condition, only a low pressure is built up at the clutch piston. Therefore the clutch does not engage, and the vehicleremains in 2WD (front wheel drive).
Reverse Deceleration l/tWDl
During reverse deceleration, the dual pump system can engage four wheel drive.When decelerating in reverse direction, the speed of the rear wheels may exceed the speed of the front wheels (due toengine braking). In this condition, the rear oil pump draws fluid through check valves B and C. Fluid discharged from therear oil pump then flows through check valve E to the clutch piston. There, pressure is regulated by two orifices.The regulated hydraulic pressure at the clutch piston may force the plates and discs of the clutch together to form a con,nection. The engaged clutch passes driving force from the transfer assembly to the rear wheels, producing 4WD.
oRtFtcEsREAR OIL PUMP
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Uneven or rough steering.Ad,ust the rack gu ide (see page 17- 15).
ll the problem is not corrected byadjusting the rack guide, replacethe gearbox.
Adjust the belttension. Replace thebelt, if necessary (see page 17-14).Belt slipping on pulley.
lf the engine stalls when thewheel is turned while the vehicleis stopped or moving at lowspeed, adjust the idle speed (seesection 111.
ldle speed low or erratic.
Check power steering lluid level. lfthe level is excessively low checkfor leaks in the system. Add fluidto the specified level.
Air in reservoir, or check powersteering tluid level.
lf fluid level is OK, check O-ringsand seals on both ends of thepump inlet hose, and the P/Spump housing mating surlacesand drive shaft oil seal for suction leaks. Check the reservoir forcracks, Replace parts as neces-
Pump belt slipping on pulley(pump stops momentarily).Adjust the belt tension (see page17-14) or replace belt.
Check if pump pressure is normaland the gauge needle travel is 500kPa (5 kgl/cm,, 71 psi) or less.Check the flow control valve if theneedle travel exceeds 500 kPa (5kgflcm', 71 psi). lI the flow controlvalve is normal, replace the pumpas an assembly,
Install the power steering pres-sure gauge, Close the pressurecontrol valve and shut off valve (if
so equipped) fully and measurethe pump pressure (see page 17-16ot 17 17).
Steering wheel kicks backduring wide turns.
7-7
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Wheel Sensor
The wheel sensors are the magnetic contactless type. As the gear pulser teeth rotate past the wheel sensor's magnetic
coil, AC current is generated. The AC frequency changes in accordance with the wheel speed. The ABS control unit detects
the wheel sensor signal frequency and thereby detects the wheel speed
at LOW SPEED
wheel Sp€od and Modulatot Control
VEHICLE SPEED
VEHICLE SPEED
WHEEL SPEED
PRESSU
OUTLETVALVE ON
OFF
INLETVALVE ON
OFF
MOTOR
ON
OFF
When the wheel speed drops sharply below the vehicle speed, the outlet valve opens momentarily to reduce the caliper
fluid pressure. The pump motor starts at this time. As the wheel speed is restored. the inlet valve opens momentarily to
increase the caliDer fluid oressure.
F
GEAR PULSER
19-31
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Description
The air conditioner system removes heat from the passenger compartment by circulating refrigerant through the systemas shown below.
High'temperature/ High-temperature/
high-pressure gas h igh-pressure liquid
Suction and compression Radiation of heat
High-temperature/
high-pressu re liq uidr raps oeons,
and removes
motsture
More liquidified
row-pressure vapor
EVAPoRAToR (-l EXPANSToN vAL
SUCTION LINEtLow-PRESSURE S|OEt
LIOUID LINE
CONDENSER
coMpREssoR Il- coruoerusenl* necetve
Less moisturized
low-pressure vapor
Absorption of heat
DISCHARGE LINEIHIGH.PRESSURE SIDEI
This vehicle uses HFC-I34a (R-l34a) refrigerant which does not contain chlorofluorocarbons. Pay attention to the follow-ing service items:
. Do not mix refrigerants CFC-12 (R-12) and HFC-l34a (R-134a). They are not compatible.. Use only the recommended polyalkyleneglycol (PAG) refrigerant oil (SP-10) designed for the R-134a compressor.Intermixing the recommended (PAG) refrigerant oil with any other refrigerant oil will result in compressor failure.. Afl Ay'C system parts (compressor, discharge line. suction line, evaporator, condenser. receiver/dryer, expansion valve,O-rings for joints) have to be proper for refrigerant R-134a. Do not confuse with R-12 parts.
. Use a halogen gas leak detector designed for refrigerant R-134a.. R-12 and R-134a refrigerant servicing equipment are not interchangeable. Use only a recovery/recycling/charging stationthat is U.L.iisted and is certified to meet the requirements of SAE J2210 to service R-134a air conditioning system.. Always recover the refrigerant R-134a with an approved recovery/recycling/charging station before disconnecting anylVC fitting.
EVAPORAYOR
22-7
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A/C Service Tips and Precautions
The air conditioner system uses HFC-'134a (R-134a) refrigerant and polyalkyleneglycol {PAG) refrigerant oil*, which are not
compatible with CFC-12 (R-12) refrigerant and mineral oil. Do not use R-12 refrigerant or mineral oil in this system, and do
not attempt to use R-12 servicing equipmenu damage to the air conditioner system or your servicing equipment will
resutr.
*KEIHIN SP-10:
. P/N 38897 - Pl3 - A01AH: 120 m{ (4 fl.oz, il.2 lmp.oz)
. P/N 38899 - Pl3 - A01: 40 mf 11113tl.oz,1.4 lmp.oz)
Use only service equipment that is U.L.-listed and is certified to meet the requirements of SAE J2210 to remove R-134a
from the air conditioner system,
CAUTION: Exposure to air conditioner refrigerant and lubricant vapor or misl can irritats eyes, nose and throat. Avoid
breathing the air conditioner refrigerant and lubricant vapor or mist,
lf accidental system discharge occurs, ventilate work area before resuming service.
R 134a service equipment or vehicle air conditioner systems should not be pressure tested or leak tested with compressed
air.
E@ Some mixtures of air and R-13,1a have been shown to be combustible at elevat€d pressures and can result
in fire or explosion causing iniury or property damage. Never use complessed air to pressure test R-l3,[a service equip-
ment or vehicle air conditioner systems.
Additional health and safety information may be obtained from the refrigerant and lubricant manufacturers.
1. Always disconnect the negative cable from the battery whenever replacing air conditioning parts.
2. Keep moisture and dust out of the system. When disconnecting any lines, plug or cap the fittings immediately; don't
remove the caps or plugs until just before you reconnect each line.
3. Before connecting any hose or line. apply a few drops of refrigerant oilto the O-ring,
4. When tightening or loosening a fitting, use a second wrench to support the matching fitting.
5. When discharging the system, use a R l34a refrigerant recovery/recycling/charging station; don't release refrigerant
into the atmosphere.
6. Add refrigerant oil after replacing the following parts.
Note these items when handling refrigerant oil:
o To avoid contamination, do not return the oil to the container once dispensed, and never mix it with other refriger-
ant oils.
. lmmediately after using the oil, replace the cap on the container, and seal it to avoid moisture absorption.
. Do not spill the refrigerant oil on the vehicle; it may damage the painu if the refrigerant oil contacts the paint, wash
it off immediately.
Condenser . 25 ml (5/6 tl.oz, 0.9 lmp.oz)
Evaporator.,................................40 m/ 11 113ll.oz,l.4 lmp.ozl
Line or hose ........... 10 ml (1/3 fl.oz, 0.4 lmp.oz)
Receiver/Dryer....... 10 ml (1/3 fl.oz, 0.4 lmp.oz)
Leakage repair............................ 25 m/ (5/6 ll.oz, 0.9 lmp.oz)
Compressor.......,..., For compressor replacement, subtract the volumg ol oil drained from the removed
compressor from 130 m{ (4 113 tl.oz, 1,6lmp.ozl, and drain the calculatsd volume of
oif from the now comprossor: 130 ml (,1 113 tl,oz, 1.6lmp'ozl - Volume of removed
compressor = Volume to drain from new compressor.
NOTE: Even if no oil is drained trom the removed compressor, don't drain more than
50mt 11 213ll,oz,1.8 lmp.oz) from the newcompressor.
22-54I
rso m r rr:0.o., r.s r-o.o.t
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A/C System Service
Pressure Test Chart
NOTE: Performance Test is on page 22-56.
Test resultsRelatad symptomsPrcbable caus€Remody
Discharge (high)pressure 6bnormallyhagh
After stopping compressor, pressuredrops to about 200 kPa 12.0 kgtlcm,,28 psi) quickly, and then lalls gradualty.
Air in systemDischarge, evacuate, and rechargewith specified amount.Evacuation: see page 22-60Charging: see page 22-61No bubbles in sight glass whencondenser is cooled by waterExcessive refrigerant in systemDischarge, evacuate, and rechargewith specilied amount.Reduced or no air flow throughcondenser. Clogged condenser or radia-tor fins. Condenser or radiator fannot wo.king properly
CleanCheck voltage and fan rpm.Check fan direction.
Line to condensor is excossivelv hot.Restricted flow of relrigerant insy$emFestricted lines
Discharge pressureabnormally lowExcessive bubbles in sight glass;condenser is not hot.Insufficient retrigerant inCheck for leak.Charge system.High and low pressures are balancedsoon after stopping compressor. Lowside is higher than normal.
. Faulty compressor discharge
. Faulty compressor seal
Replace the comprossor.
Outlet ot expansion valve is notfrosted, low-pressure gauge indicates
' Faulty expansion valve. Moisture in system. Replace. Discharge, evacuate, andrecharge with specified amount.Suction {low) pros,sure abnormallyExcessive bubbles in sight glass;condenser is not hot.Insufficiont relrigerant inRepair the leaks.Discharge, evacuate, andrecharge with specified amount.Charge as r€quired.Expansion valve is not frosted, andlow-pressure line is not cold. Low-pressure gauge indicates vacuum.
' Frozen expansion valvelMoisture in system). Faulty expansion valve
. Discharge, evacuate, andrecharge with specitied amount.. Replace th€ expansion valve.Discharge temperature is low, and theair llow trom vents is restricted.Frozen evaporatorRun the fan with compressor off,then check evaporator tempera,ture sensor.Expansion valve is frosted.Clogged expansion valveClean or replace.Feceiver/dryer outlet is cool, and inlotrs w6rm (should be warm duringoperation).
Clogged receiver/dryerReplace
Suction pressureabnormally highLow-pressure hose and check joint arecooler than tho temperature aroundevaporator.
. Expansion valve open too long. Loose expansion capillarytube
Repair or roplace.
Suction pressure is lowored whencondenser is cooled by water.Excessive refrigerant in systemDischarge, evacuate, and rechargewath specified amount.High and low-pressure are equalizedas soon as tho compressor is stopped,and both gauges tluctuate whilerunning.
Faulty gasketFaulty high-pressure valveForeign panicle stuck in high-
Replace the compressor.
Slction and dis,charge pressutesabnormally high
Reduced air flow through condens€r,. Clogged condenser orradiator tins. Condenser or radiator fannot working properly
CleanCheck voltage and fan rpm.Check Ian direction.
No bubbles in sight glass whencondenser is cooled by walerExcessive refrigerant jn systemDischarge, evacuate, and rechargewith specified amount.Suction and dis-charge pressureabnormally low
Low-pressure hose and motalendareas are cooterlhan evaporator.Clogged or kinked low-pressure hose pansRepair or replace.
Temperature around expansion valvers too low compared with that aroundClogged high-pressure lineRepair or replace.
Refrigerant leaksCompressor clutch is diny.Compressor shaft seal leakingReplace the compressor.Compressor boltls) are dirty.Leaking around bolt(s)Tighton bolt{s) or replacecompressor.Compressor gasket is wet with oil.Gasket leakingReplace the compressor,
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