Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 206

6A–11

ENGINE MECHANICAL (6VE1 3.5L)

Condition

Correction

Possible cause

Engine overheating

Level of Engine Coolant too low

Replenish

Fan clutch defective

Replace

Incorrect fan installed

Replace

Thermostat defective

Replace

Engine Coolant pump defective

Correct or replace

Radiator clogged

Clean or replace

Radiator filler cap defective

Replace

Level of oil in engine crankcase too
low or wrong engine oil

Change or replenish

Resistance in exhaust system
increased

Clean exhaust system or replace
defective parts

Throttle Position Sensor adjustment
incorrect

Replace with Throttle Valve ASM

Throttle Position Sensor circuit open
or shorted

Correct or replace

Cylinder head gasket damaged

Replace

Engine overcooling

Thermostat defective

Replace (Use a thermostat set to
open at 82

°

C (180

°

F))

Engine lacks compression

————

Refer to Hard Start

Others

Tire inflation pressure abnormal

Adjust to recommended pressures

Brake drag

Adjust

Clutch slipping

Adjust or replace

Level of oil in engine crankcase too
high

Correct level of engine oil

Exhaust Gas Recirculation Valve
defective

Replace

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

y

j

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

y

g

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

k

bi

d

h

i

l

Piston clearance increased due to
cylinder wear

Replace piston and cylinder body

makes a combined mechanical
thumping noise which increases

Piston seized

Replace piston and cylinder body

g

when engine is suddenly accelerated
but diminishes gradually 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

6A–13

ENGINE MECHANICAL (6VE1 3.5L)

Troubleshooting Procedure for Slapping or Hitting etc Noise
The slapping sound stops when spark plug on bad
cylinder is shorted out.

Condition

Possible cause

Correction

Timing belt noise

Timing belt tension is incorrect

Replace pusher or adjust the tension
pulley or replace timing belt

Tensioner bearing defective

Replace

Timing belt defective

Replace

Timing pulley defective

Replace

Timing belt comes in contact with
timing cover

Replace timing belt and timing cover

Valve noise

Valve clearance incorrect

Replace adjusting shim

Valve and valve guide seized

Replace valve and valve guide

Valve spring broken or weakened

Replace

Valve seat off–positioned

Correct

Camshaft worn out

Replace

Crankshaft noise

Crankshaft end play excessive
(noise occurs when clutch is
engaged)

Replace thrust bearing

Engine knocking

Preignition due to use of spark plugs
of inadequate heat range

Install Spark Plugs of adequate heat
range

Carbon deposits in combustion
chambers

Clean

Fuel too low in octane rating

Replace fuel

Wide Open Throttle enrichment
system failure

Refer to Section 6E

Selection of transmission gear
incorrect

Caution operator of incorrect gear
selection

Engine overheating

Refer to “Engine Lacks Power”

Others

Water pump defective

Replace

Drive belt slipping

Replace auto tensioner or drive belt

6A–14

ENGINE MECHANICAL (6VE1 3.5L)

Abnormal Combustion

Condition

Possible cause

Correction

Trouble in fuel system

Fuel pressure control valve defective

Replace

Fuel filter clogged

Replace

Fuel pump clogged

Clean or replace

Fuel tank or fuel pipe clogged

Clean or replace

Fuel injector clogged

Clean or replace

Fuel pump relay defective

Replace

Power supply cable for fuel pump
broken or poor connections

Reconnect, correct or replace

Mass Airflow (MAF) Sensor circuit
open or defective

Correct or replace

MAF Sensor defective

Replace

Manifold Absolute Pressure Sensor
circuit open or shorted

Correct or replace

Manifold Absolute Pressure Sensor
defective

Replace

Engine Coolant Temperature (ECT)
Sensor circuit open or shorted

Correct or replace

ECT Sensor defective

Replace

Throttle Position Sensor adjustment
incorrect

Readjust

Throttle Position Sensor defective

Replace

Throttle Position Sensor connector
poor connections

Reconnect

Vehicle Speed Sensor cable poor
connections or defective

Correct or replace

Vehicle Speed Sensor loosely fixed

Fix tightly

Vehicle Speed Sensor in wrong
contact or defective

Replace

Powertrain Control Module cable
poor connections or defective

Correct or replace

Trouble in emission control system

Heated Oxygen Sensor circuit open

Correct or replace

Heated Oxygen Sensor defective

Replace

Signal vacuum hose loosely fitted or
defective

Correct or replace

EGR Valve circuit open or shorted

Correct or replace

Exhaust Gas Recirculation Valve
defective

Replace

ECT Sensor circuit open or shorted

Correct or replace

Canister Purge Valve circuit open or
shorted

Correct or replace

Canister Purge Valve defective

Replace

ECT Sensor defective

Replace

Positive Crankcase Ventilation
(PCV) valve and hose clogged

Correct or replace

Evaporator system

Refer to Section 6E

Trouble in ignition system

————

Refer to “Engine Lacks Power”