ENGINE
3.59
TROUBLESHOOTING, CONT
Piston Failure - Scoring
S Lack of lubrication
S Dirt entering engine through cracks
in air filter or ducts
S Engine oil dirty or contaminated
Excessive Smoke and Carbon Buildup
S Excessive piston-to-cylinder
clearance
S Wet sumping
S Worn rings, piston, or cylinder
S Worn valve guides or seals
S Restricted breather
S Air filter dirty or contaminated
Low Compression
S Cylinder head gasket leak
S No valve clearance ( cam wear )
S Cylinder or piston worn
S Piston rings worn, leaking, broken,
or sticking
S Bent valve or stuck valve
S Valvespringbrokenorweak
S Valve not seating properly (bent or
carbon accumulated on sealing
surface)
S Rocker arm sticking
Backfiring
S ETC or speed limiter system
malfunction
S Fouled spark plug or incorrect plug
or plug gap
S Carburetion faulty - lean condition
S Exhaust system air leaks
S Ignition system faulty:
Spark plug cap cracked/broken
Ignition coil faulty
Ignition or kill switch circuit faulty
Ignition timing incorrect
Sheared flywheel key
S Poor connections in ignition system
S Valve sticking
S Air leaks in intake
S Lean condition
COOLING SYSTEM
TROUBLESHOOTING
Overheating
S Low coolant level
S Air in cooling system
S Wrong type/mix of coolant
S Faulty pressure cap or system
leaks
S Restricted system (mud or debris in
radiator fins causing restriction to
air flow, passages blocked in
radiator, lines, pump, or water
jacket, accident damage)
S Lean mixture (restricted jets, vents,
fuel pump or fuel valve)
S Fuel pump output weak
S Electrical malfunction
S Water pump failure/ Loose impeller
S Thermistor failure
S Cooling fan inoperative or turning
too slowly (perform current draw
test)
S Ignition timing misadjusted
S Low oil level
S Spark plug incorrect heat range
S Faulty hot light circuit
S Thermostat stuck closed or not
opening completely
Temperature Too Low
S Thermostat stuck open
Leak at Water Pump Weep Hole
S Faulty water pump mechanical seal
(coolant leak)
S Faulty pump shaft oil seal (oil leak)
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