The chart below shows the most common questions asked by owners of Detroit Diesel® engines 12V149 Turbo when trying to troubleshoot why their engines underperform.  It categorizes areas of possible malfunction, likely cause and recommended action to bring your new, rebuilt or used  Detroit Diesel® engine back to proper operation.  The chart will give you confidence when speaking with your Detroit Diesel® engine mechanic or ordering parts.  As a quick reference guide only, the chart must not be thought of as a substitute for the use of your Detroit Diesel® engine 12V149 Turbo Owner's operating or service manual. PROBLEM POSSIBLE REASON CHECK
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Engine will not start
Lack of air intake or restricted air intake
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Broken blower shaft
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Worn out blower shaft
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Defective fuel pump
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Defective starter
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Discharged battery
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High exhaust back pressure
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Black smoke coming out of engine
Defective injector
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Contaminated fuel
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Broken or worn cylinder parts
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Engine overloaded
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Faulty intercooler or aftercooler (for turbo engines only)
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White smoke coming out of engine
Broken piston ring
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Incorrectly installed ring set
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Defective injector
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Fuel quality or grade
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Long idle periods
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Broken or bent push rod
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Injector or governor improperly adjusted
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Low engine oil pressure
Water in engine oil pan
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Fuel in engine oil pan
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Defective oil cooler
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Engine overloaded
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Crankcase overfilled
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Low engine RPM
Improperly working injector
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Governor calibration
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Hi engine RPM
Governor calibration
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Engine overheating
Defective fresh water pump
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Defective raw water pump (marine engines only)
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Defective thermostat or thermostat seal
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Clogged radiator or heat exchanger (marine engine only)
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Grey smoke coming out of engine
Long idle periods
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Defective intercooler or aftercooler (for turbo engine only)
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Restricted air intake
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Defective injector
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Contaminated fuel
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Blower or turbocharger seals leaking
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Geartrain makes noises
Low oil level
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Engine driven accesories
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Damage main or rod bearing
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