Workshop Manual

6A–12
ENGINE MECHANICAL (6VE1 3.5L)
Engine Noisy
Abnormal engine noise often consists of various noises
originating in rotating parts, sliding parts and other
moving parts of the engine. It is, therefore, advisable to
locate the source of noise systematically.
Troubleshooting Procedure for Crankshaft Journals or Crankshaft Bearing Noise
Condition Possible cause Correction
Noise from crank journals or from
crank bearings
(Faulty crank journals and crank
Oil clearance increased due to worn
crank journals or crank bearings
Replace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
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bearings usually make dull noise that
becomes more evident when
accelerating)
Crankshaft out of round Replace crank bearings and
crankshaft or regrind crankshaft and
install the undersize bearing
Crank bearing seized Crank bearing seized Replace crank
bearings and crankshaft or regrind
crankshaft and install the undersize
bearing
Troubleshooting Procedure for Connecting Rods or Connecting Rod Bearing Noise
Short out each spark plug in sequence using insulated
spark plug wire removers. Locate cylinder with defective
bearing by listening for abnormal noise that stops when
spark plug is shorted out.
Condition Possible cause Correction
Noise from connecting rods or from
connecting rod bearings
(Faulty connecting rods or
Bearing or crankshaft pin worn Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
yg
connecting rod bearings usually
make an abnormal noise slightly
higher than the crank bearing noise,
which becomes more evident when
Crankpin out of round Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
which
becomes
more
evident
when
engine is accelerated)
Connecting rod bent Correct or replace
g)
Connecting rod bearing seized Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
Troubleshooting Procedure for Piston and Cylinder Noise
Abnormal noise stops when the spark plug on the cylinder
with defective part is shorted out.
Condition
Possible cause Correction
Piston and cylinder noise
(Faulty piston or cylinder usually
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Piston clearance increased due to
cylinder wear
Replace piston and cylinder body
ma
k
es a com
bi
ne
d
mec
h
an
i
ca
l
thumping noise which increases
Piston seized Replace piston and cylinder body
g
when engine is suddenly accelerated
but diminishes
g
raduall
y
as the
Piston ring broken Replace piston and cylinder body
but
diminishes
gradually
as
the
engine warms up)
Piston defective Replace pistons and others
Troubleshooting Procedure for Piston Pin Noise
Short out each spark plug and listen for change in engine
noise.
Condition
Possible cause Correction
Piston pin noise
(Piston makes noise each time it
goes up and down)
Piston pin or piston pin hole worn Replace piston, piston pin and
connecting rod assy