Lexus SC300 / Lexus SC400. Manual — part 531

A pressure feeding lubrication system has been adopted to supply oil to the moving parts of this engine. The

lubrication system consists of an oil pan, oil pump, oil filter and other external parts which supply oil to the moving
parts in the engine block. The oil circuit is shown in the illustration at the top of the previous page. Oil from the
oil pan is pumped up by the oil pump. After it passes through the oil filter, it is fed through the various oil holes
in the crankshaft and cylinder block. After passing through the cylinder block and performing its lubricating func-
tion, the oil is returned by gravity to the oil pan. A dipstick on the center left side of the cylinder block is provided
to check the oil level.

OIL PUMP

The oil pump pumps up oil from the oil pan and sends it under pressure to the various parts of the engine.

An oil strainer is mounted in front of the inlet to the oil pump. The oil pump itself is a trochoid type pump, inside
of which there is a drive rotor and a driven rotor. When the drive rotor rotates, the driven rotor rotates in the same
direction, and since the axis of the driven rotor shaft is different from the center of the driven rotor, the space
between the two rotors is changed as they rotate. Oil is drawn in when the space is wide and is discharged when
the space in narrow.

OIL PRESSURE REGULATOR

At high engine speeds, the engine oil supplied by the oil pump exceeds the capacity of the engine to utilize

it. For that reason, the oil pressure regulator works to prevent an oversupply of oil. During normal oil supply, a
coil spring and valve keep the bypass closed, but when too much oil is being fed, the pressure become extremely
high, overpowering the force of the spring and opening the valves. This allows the excess oil to flow through
the valve and return to the oil pump inlet.

OIL FILTER

The oil filter is a full flow type filter with a built–in paper filter element. Particles of metal from wear, airborne

dirt, carbon and other impurities can get into the oil during use and could cause accelerated wear or seizing if
allowed to circulate through the engine. The oil filter, integrated into the oil line, removes these impurities as the
oil passes through it. The filter is mounted outside the engine to simplify replacement of the filter element. A relief
valve is also included ahead of the filter element to relieve the high oil pressure in case the filter element be-
comes clogged with impurities. The relief valve opens when the oil pressure overpowers the force of the spring.
Oil passing through the relief valve by–passes the oil filter and flows directly into the main oil hole in the engine.

–

LUBRICATION SYSTEM

Precautions

LU–3

PREPARATION

SST (SPECIAL SERVICE TOOLS)

RECOMMENDED TOOLS

EQUIPMENT

Part Name

Note

Oil pressure gauge

Precision straight edge

Oil pump

Torque wrench

LUBRICANT

Item

Capacity

Classification

Item

Liters

US qts

lmp. qts

Classification

Engine oil

API grade SG, Energy–Conserving II

Dry fill

6 0

6 3

5 3

multigrade. Recommended viscosity is

Drain and refill

6.0

6.3

5.3

g

y

as shown, with SAE 5W–30 being the

w/ Oil filter change

4.8

5.1

4.2

preferred engine oil.

w/o Oil filter change

4.5

4.8

5.3

g

SSM (SPECIAL SERVICE MATERIALS)

Part Name

Part No.

Use etc.

Seal packing or equivalent

08826–00080

Oil pump, Oil pan

Adhesive 1344,

Three bond 1344,

08833–00080

Oil pressure switch

Loctite 242 or equivalent

LU–4

–

LUBRICATION SYSTEM

System Circuit, Operation

OIL PRESSURE CHECK

1.

CHECK ENGINE OIL QUALITY
Check the oil for deterioration, presence of water, discoloring
or thinning.
If the quality is poor, replace the oil.

Oil grade: API grade SG, Energy–Conserving II multigrade.

Recommended viscosity is as shown, with SAE 5W–30 being

the preferred engine oil.

2.

CHECK ENGINE OIL LEVEL
The oil level should be between the ”L” and ”F” marks on the
dipstick.
If low, check for the leakage and add oil up to ”F” mark.

3.

REMOVE ENGINE UNDER COVER

4.

REMOVE DRIVE BELT
Loosen the drive belt tension by turning the drive belt tension-
er clockwise, and remove the drive belt.

5. DISCONNECT A/C COMPRESSOR WITHOUT

DISCONNECTING HOSES
(a) Disconnect the compressor connector.
(b) Remove the four mounting bolts and nut.
(c) Remove the throught bolt, and disconnect the

compressor from the engine.

HINT: Put aside the compressor, and suspend it.

6. REMOVE OIL PRESSURE SWITCH, AND INSTALL OIL

PRESSURE GAUGE
(a) Disconnect the oil pressure switch connector.
(b) Using SST, remove the oil pressure switch.

SST 09816–30010

(c) Install an oil pressure gauge.

–

LUBRICATION SYSTEM

Oil pressure Check

LU–5

7.

REINSTALL A/C COMPRESSOR
(a) Install the A/C compressor with the through bolt, four

bolts and nut.

Torque:

Through bolt 26 N

⋅

m (265 kgf

⋅

cm, 19 ft

⋅

lbf)

Bolt and nut 52 N

⋅

m (530 kgf

⋅

cm, 38 ft

⋅

lbf)

(b) Connect the compressor connector.

8.

REINSTALL DRIVE BELT
Install the drive belt by turning the drive belt tensioner clock-
wise.

9.

WARM UP ENGINE

Allow the engine to warm up to normal operating
temperature.

10. CHECK OIL PRESSURE

Oil pressure:

At idle speed

29 kPa (0.3 kgf/cm

, 4.3 psi)

or more

At 3,000 rpm

294–539 kPa

(3.0–5.5 kgf/cm

, 78 psi)

11. REMOVE DRIVE BELT (See step 4)

12. DISCONNECT A/C COMPRESSOR FROM ENGINE

(See step 5)

13. REMOVE OIL PRESSURE GAUGE AND REINSTALL OIL

PRESSURE SWITCH
(a) Remove an oil pressure gauge.
(b) Apply

adhesive to two or three threads of the oil

pressure switch.

Adhesive:

Part No. 08833–00080, THREE BOND 1344,

LOCTITE 242 or equivalent

(c) Using SST, install the oil pressure switch.
SST 09816–30010

Torque: 14 N

⋅

m (150 kgf

⋅

cm, 11 ft

⋅

lbf)

(d) Connect the compressor connector.

14. REINSTALL A/C COMPRESSOR (See step 7)

15. REINSTALL DRIVE BELT (See step 8)

16. START ENGINE AND CHECK FOR LEAKS

17. REINSTALL ENGINE UNDER COVER

LU–6

–

LUBRICATION SYSTEM

Oil pressure Check