Lexus SC300 / Lexus SC400. Manual - part 705

(b)  Using a plastic–faced hammer, carefully tap out the front

housing.

(c)  Remove the O–ring from the casing.

7. 

REMOVE FRONT THRUST WASHER AND DRIVE SHAFT

8. 

REMOVE DRIVE AND DRIVEN ROTORS

9. 

REMOVE REAR THRUST WASHER

10. REMOVE CASING

(a)  Remove the casing.
(b)  Remove the O–ring from the rear housing.

11.  REMOUNT REAR HOUSING

HINT: Mount the parts in a vise as shown in the illustration.

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COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Hydraulic Pump)

CO–33

12.  REMOVE SPOOL VALVE

(a)  Using a 10 mm hexagon wrench, remove the end plug

and following parts:

(1)

Spool valve

(2)

Compression spring

(3)

Spool sleeve

(b)  Remove the O–ring from the end plug.

INSPECTION OF HYDRAULIC PUMP

1. CLEAN 

DISASSEMBLED 

PARTS

Using a cleaner and compressed air, clean the disassembled
parts.
CAUTION: Thoroughly clean the oil passages of the rear
housing. Oil passage A includes a filter which should be
cleaned carefully.

2. 

INSPECT SPOOL VALVE
(a)  Coat the spool valve with PS fluid, and check that it falls

smoothly into the spool sleeve by its own weight.

(b)  Check the spool valve for leakage.

Close one of the holes and apply compressed air
392–490 kPa (4–5 kgf/cm2, 57–71 psi) into the opposite
side, check that air does not come out of the end hole.

If it doesn’t, replace the spool valve and sleeve as a set.

3. 

INSPECT SPOOL COMPRESSION SPRING
Using a vernier calipers, measure the free length of the com-
pression spring.

Free length: 45.8 mm (1.803 in.)

If the free length is not as specified, replace the compression
spring.

CO–34

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COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Hydraulic Pump)

4. 

INSPECT DRIVE AND DRIVEN ROTORS

A.

Install casing and rotors to rear housing
Face the dot mark of the rotors upward.

B.

Inspect rotor side clearance
HINT: Before measuring the clearance, remove one side of
the rotor.
Using a feeler gauge and precision straight edge, measure
the clearance between the rotor and precision straight edge.

Standard side clearance:

Drive rotor 0.02 mm (0.0008 in.)

Driven rotor 0.03 mm (0.0012 in.)

Maximum side clearance:

Drive rotor 0.03 mm (0.0012 in.)

Driven rotor 0.04 mm (0.0016 in.)

If the clearance is greater than maximum, replace the rotors
as a set. If necessary, replace the housings.

C.

Inspect rotor body clearance
Using a feeler gauge, measure the clearance between the
driven rotor and casing.

Standard body clearance: 0.05–0.09 mm

(0.0020–0.0035 in.)

Maximum body clearance: 0.10 mm (0.0039 in.)

If the clearance is greater than maximum, replace the rotors
as a set. If necessary, replace the casing.

D.

Inspect rotor tip clearance
Using a feeler gauge, measure the clearance of all the six
drive rotor tips between the drive and driven rotors.

Standard tip clearance: 0.02 mm (0.0008 in.)

Maximum tip clearance: 0.03 mm (0.0012 in.)

If the clearance is greater than maximum, replace the rotors
as a set.

E.

Remove rotors and causing from rear housing

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COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Hydraulic Pump)

CO–35

5. 

INSPECT OIL CLEARANCE OF DRIVE SHAFT
(a)  Using a caliper gauge, measure the bushing inside

diameter on the housing.

Bushing inside diameter: 17.00–17.05 mm

(0.6693–0.6713 in.)

(b)  Using a micrometer, measure the drive shaft diameter.

Shaft diameter: 16.97–16.98 mm

(0.6681–0.6685 in.)

(c) Subtract 

the drive shaft diameter measurement from the

bushing inside diameter measurement.

Standard clearance: 0.02–0.08 mm

(0.0008–0.0031 in.)

Maximum clearance: 0.08 mm (0.0031 in.)

If the clearance is greater than maximum, replace the shaft.
If necessary, replace the housings.

6. 

INSPECT SOLENOID VALVE RESISTANCE
Using an ohmmeter, measure the resistance between the ter-
minals.

Resistance (Cold): 7.5–8.5 

CO–36

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COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Hydraulic Pump)