Lexus SC300 / Lexus SC400. Service manual — part 412

The 1 UZ–FE engine has 8–cylinders in a V–arrangement at a bank angle of 90

. From the front of the RH

bank cylinders are numbered 2–4–6–8, and from the front of the LH bank cylinders are numbered 1 –3–5–7.
The crankshaft is supported by 5 bearings specified by the inside of the crankcase. These bearings are made
of a copper and lead alloy.

The crankshaft is integrated with 8 weights which are cast along with it for balancing. Oil holes are built

into the center of the crankshaft for supplying oil to the connecting rods, pistons and other components.

The ignition order is 1–8–4–3–6–5–7–2. The cylinder head is made of aluminum alloy, with a cross flow

type intake and exhaust layout and with pent–roof type combustion chambers. The spark plugs are located in
the center of the combustion chambers.

At the front and rear of the intake manifold, a water passage has been provided which connects the RH

and LH cylinder heads.

Exhaust and intake valves are equipped with irregular pitch springs made of special valve spring carbon

steel which are capable of following no matter what the engine speed.

The RH and LH intake camshafts are driven by a single timing belt, and a gear on the intake camshaft en-

gages with a gear on the exhaust camshaft to drive it. The camshaft journal is supported at 5 (intake) or 4 (ex-
haust) places between the valve lifters of each cylinder and on the front end of the cylinder head. Lubrication
of the cam journal gear is accomplished by oil being supplied through the oiler port in the center of the camshaft.

Adjustment of the valve clearance is done by means of an outer shim type system, in which valve adjusting

shims are located above the valve lifters. This permits replacement of the shims without removal of the cam-
shafts.

Pistons are made of high temperature–resistant aluminum alloy, and a depression is built into the piston

head to prevent interference with valves.

Piston pins are the full–floating type, with the pins fastened to neither the piston boss nor the connecting

rods. Instead, snap rings are fitted on both ends of the pins, preventing the pins from falling out.

The No.1 compression ring is made of steel and the No.2 compression ring is made of cast iron. The oil

ring is made of a combination of steel and stainless steel. The outer diameter of each piston ring is slightly larger
than the diameter of the piston and the flexibility of the rings allows them to hug the cylinder walls when they
are mounted on the piston. Compression rings No.1 and No.2 work to prevent the leakage of gas from the cylin-
der and the oil ring works to scrape oil off the cylinder walls to prevent it from entering the combustion chamber.

The cylinder block is made of aluminum alloy with a bank angle of 90

. Cast iron cylinders are installed

inside the cylinder block. It has 8 cylinders which are approximately twice the length of the piston stroke. The
top of each cylinder is closed off by the cylinder heads and the lower end of the cylinders becomes the crank-
case, in which the crankshaft is installed. In addition, the cylinder block contains a water jacket, through which
coolant is pumped to cool the cylinders.

The No.1 and No.2 oil pans are bolted onto the bottom of the cylinder block. The No.1 oil pan is made of

aluminum alloy. The No.2 oil pan is an oil reservoir made of pressed steel sheet. An oil level sensor is installed
in the No.1 oil pan (If the oil level drops below a set level, a warning light lights up.). A oil pan baffle plate keeps
sufficient oil in the bottom of the No.2 oil pan even when the vehicle is tilted. This dividing plate also prevents
the oil from making waves when the vehicle is stopped suddenly and the oil shifts away from the oil pump suction
pipe.

Plastic region tightening bolts are used for the cylinder head, main bearing cap and connecting rod.

EM–4

–

ENGINE MECHANICAL

Operation

PREPARATION

SST (SPECIAL SERVICE TOOLS)

09201–70010

Valve Guide Bushing

Remover & Replacer

09202–70010

Valve Spring

Compressor

09213–31021

Crankshaft Pulley

Puller

09213–54015

Crankshaft Pulley

Holding Toll

(91651–60855)

(Bolt)

(09213–00020)

(Body with Bolt)

(09213–00030)

(Handle)

(09213–00040)

(Attachment Set)

(09213–00050)

(Bolt Set)

09213–60017

Crankshaft Pulley &

Gear Puller Set

(09248–05011)

(Valve Lifter Press)

09222–30010

Connecting Rod

Bushing Remover

& Replacer

09223–15030

Oil Seal and

Bearing Replacer

09248–55020

Valve Clearance

Adjust Tool Set

Crankshaft rear oil seal

EM–4

–

ENGINE MECHANICAL

Preparation

SST (SPECIAL SERVICE TOOLS) (Cont’d)

(09248–05021)

(Valve Lifter

Stopper)

09316–60010

Transmission &

Transfer Bearing

Replacer

Crankshaft timing pulley

09278–54012

Drive Shaft Holding

Tool

M/T (W58) only

09325–20010

Transmission Oil

Plug

(09316–00010)

(Replacer Pipe)

Crankshaft front oil seal and camshaft oil seal

(09316–00050)

(Replacer ”D”)

Camshaft oil seal

A/T (A340E) only

09325–40010

Transmission Oil

Plug

Crankshaft pulley

09330–00021

Companion Flange

Holding Tool

09608–30022

Front Hub Bearing

Replacer Set

Knock sensor and oil pressure switch

09816–30010

Oil Pressure

Switch Socket

(09608–05010)

(Handle)

Crankshaft rear oiil seal

RECOMMENDED TOOLS

Cylinder head bolt

09043–50100

10 mm Bi–Hexagon

wrench

A/C compressor mounting through bolt

09044–00020

Torx Socket

E10

–

ENGINE MECHANICAL

Preparation

EM–5

RECOMMENDED TOOLS (Cont’d)

For suspending engine

09090–04010

Engine Sling

Device

Plug for the vacuum hose. fuel hose etc.

09258–00030

Hose Plug Set

09200–00010

Engine Adjust

Kit

EQUIPMENT

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Part Name

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Note

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Caliper gauge

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CO/HC analyzer

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Compression gauge

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Cylinder compression pressure

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Connecting rod aligner

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Cylinder gauge

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Dial indicator

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Engine tune–up tester

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Feeler gauge

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Micrometer

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Straight edge

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Spring tester

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Valve spring

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Steel square

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Valve spring

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Torque wrench

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Vernier caliper

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SSM (SPECIAL SERVICE MATERIALS)

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Part Name

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Part No.

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Use etc.

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Seal packing or equivalent

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08826–00080

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Camshaft bearing cap, Cylinder head cover,
Rear oil seal retainer and Oil pump

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Adhesive 1324,
THREE BOND 1324 or equivalent

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08833–00070

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Drive plate mounting bolt

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Adhesive 1344,
THREE BOND 1344,
LOCTITE 242 or equivalent

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08833–00080

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Idler pulley mounting bolt

EM–6

–

ENGINE MECHANICAL

Preparation

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Lexus SC300 / Lexus SC400. Service manual — part 412

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