Isuzu 1999 RODEO Workshop Manual page 1097

6A–12 ENGINE MECHANICAL (6VD1 3.2L)
Troubleshooting Procedure
Short out each spark plug in sequence using insulated
spark plug wire removers. Locate cylinder with defective
Condition
Noise from connecting rods or from
connecting rod bearings
(Faulty y connecting g
connecting rod bearings usually
make an abnormal noise slightly
higher than the crank bearing noise,
which becomes more evident when which becomes more evident when
engine is accelerated) g )
Troubleshooting Procedure
Abnormal noise stops when the spark plug on the cylinder
with defective part is shorted out.
Condition
Piston and cylinder noise
(Faulty piston or cylinder usually
makes a combined mechanical k bi d
thumping noise which increases g
when engine is suddenly accelerated
but diminishes gradually as the but diminishes gradually as the
engine warms up)
Troubleshooting Procedure
Short out each spark plug and listen for change in engine
noise.
Condition
Piston pin noise
(Piston makes noise each time it
goes up and down)
Possible cause
Bearing or crankshaft pin worn
rods or
Crankpin out of round
Connecting rod bent
Connecting rod bearing seized
Possible cause
Piston clearance increased due to
cylinder wear
h i l
Piston seized
Piston ring broken
Piston defective
Possible cause
Piston pin or piston pin hole worn
bearing by listening for abnormal noise that stops when
spark plug is shorted out.
Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
Correct or replace
Replace connecting rod bearings
and crankshaft or regrind crankshaft
pin and install the undersize bearing
Replace piston and cylinder body
Replace piston and cylinder body
Replace piston and cylinder body
Replace pistons and others
Replace piston, piston pin and
connecting rod assy
Correction
Correction
Correction