Daewoo Nubira User Manual page 409

GENERAL ENGINE INFORMATION
DIAGNOSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
COMPRESSION TEST
OIL PRESSURE TEST
OIL LEAK DIAGNOSIS
KNOCK DIAGNOSIS
DIAGNOSIS
COMPRESSION TEST
Important : Disconnect the Crankshaft Position Sensor
(CPS) connector to disable the fuel and the ignition sys-
tems.
Test the compression pressure for each cylinder. Low
compression pressure may be the fault of the valves or the
pistons. The following conditions should be considered
when checking the cylinder compression:
S
The engine should be at normal operating tempera-
ture.
S
The throttle must be wide open.
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All the spark plugs should be removed.
S
The battery must be at or near full charge.
1. Place approximately three squirts of oil from a
plunger type oiler into each spark plug port.
2. Insert the engine compression gauge into each
spark plug port.
SECTION : 1A
TABLE OF CONTENTS
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1A–1 NOISE DIAGNOSIS
1A–1
GENERAL INFORMATION
1A–2
CLEANLINESS AND CARE
1A–3
1A–4 ON–ENGINE SERVICE
3. Crank test each cylinder with four to five compres-
sion strokes using the starter motor.
4. The lowest reading should not be less than 70% of
the highest reading. The compression gauge read-
ing should not be less than 689 kPa (100 psi) for
any of the cylinders.
5. Examine the gauge readings obtained after the four
"puffs" per cylinder are obtained from cranking the
starter motor. The readings are explained in the
following descriptions:
S
Normal Condition – Compression builds up quickly
and evenly to specified compression on each cylin-
der.
S
Piston Rings Faulty – Compression is low on the
first stroke and tends to build up on following
strokes, but does not reach normal. The compres-
sion pressure improves considerably with the addi-
tion of oil into the cylinder.
S
Valves Faulty – Low compression pressure on the
first stroke. The compression pressure does not
tend to build up on the following strokes. The com-
pression pressure does not improve much with the
addition of oil into the cylinder.
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1A–8
1A–11
1A–11
1A–11