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The chart below shows the most common questions asked by owners of Detroit Diesel® engines 6V71 Natural 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 6V71 Natural 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
Worn out blower shaft
Defective fuel pump
Defective starter
Discharged battery
High exhaust back pressure
Black smoke coming out of engine
Defective injector
Contaminated fuel
Broken or worn cylinder parts
Engine overloaded
Faulty intercooler or aftercooler (for turbo engines only)
White smoke coming out of engine
Broken piston ring
Incorrectly installed ring set
Defective injector
Fuel quality or grade
Long idle periods
Broken or bent push rod
Injector or governor improperly adjusted
Low engine oil pressure
Water in engine oil pan
Fuel in engine oil pan
Defective oil cooler
Engine overloaded
Crankcase overfilled
Low engine RPM
Improperly working injector
Governor calibration
Hi engine RPM
Governor calibration
Engine overheating
Defective fresh water pump
Defective raw water pump (marine engines only)
Defective thermostat or thermostat seal
Clogged radiator or heat exchanger (marine engine only)
Grey smoke coming out of engine
Long idle periods
Defective intercooler or aftercooler (for turbo engine only)
Restricted air intake
Defective injector
Contaminated fuel
Blower or turbocharger seals leaking
Geartrain makes noises
Low oil level
Engine driven accesories
Damage main or rod bearing
Detroit Diesel 6V71 Usefull Information
This engine will have a model number (eight digit code in XXXX-XXXX format) that will start with 706, such as 7062-7201. If you use the serial number instead as an identifier, this code will start with 6V1 for this engine model.
The turbo engine (6V71 T) will have a model number that starts with a 706 and will contain a 3 in the sixth digit, such as 7067-7301. If the sixth digit is a 2, then your engine is a natural, or non-turbo engine.
Detroit Diesel 6V71 Specs and General Info
The Detroit Diesel 6V71 has six cylinders, a displacement of 425.6 inches ³, a bore of 4.25 inches and a stroke of 5 inches, and four main bearings.
Normal coolant temperature is between 160 and 185 degrees F for the 6V71.
Coolant capacity is 7.5 gallons.
Normal oil temperature is between 200 and 235 degrees F.
Normal oil pressure (PSI) is between 40-55 at 1200 RPM, and 50-70 at 2100 RPM.
Oil capacity is 22 quarts.
Torque and Horsepower
Listed below is the torque and horsepower information for the 6V71 Detroit. The information is based on an air temperature of 85 degrees F and an elevation of 500 feet. Brake horsepower is used to measure horsepower.
Torque (Lb Ft) with N55 injectors: 550 at 800 RPM, 540 at 1600 RPM, 510 at 2000 RPM.
Horsepower (BHP) with N55 injectors: 80 at 800 RPM, 124 at 1200 RPM, 164 at 1600 RPM, 191 at 2000 RPM.
Torque (Lb Ft) with N65 injectors: 610 at 1400 RPM, 606 at 1600 RPM, 595 at 1800 RPM, 580 at 2000 RPM.
Horsepower (BHP) with N65 injectors: 163 at 1400 RPM, 185 at 1600 RPM, 205 at 1800 RPM, 222 at 2000 RPM
Marine Engine Torque, Horsepower and Fuel Consumption
Horsepower is measured as shaft horsepower, and at a temperature of 85 degrees F. Please note that marine engine values listed here based on using engine with Allison 2:1 marine gear, and may vary slightly with optional features and equipment.
Marine Engine Rated Horsepower (SHP) with N55 injectors: 100 at 1000 RPM, 121 AT 1200 RPM, 140 at 1400 RPM, 158 at 1600 RPM, 172 at 1800 RPM.
Fuel Consumption with above conditions: 7 gal/hour at 1200 RPM, 9.5 gal/hour at 1800 RPM.
Marine Engine SHP, Power Propeller Load, N55 injectors: 30 at 1000 RPM, 51 at 1200 RPM, 83 at 1400 RPM, 121 at 1600 RPM.
Fuel Consumption with above conditions: 3.5 gal/ hour at 1200 RPM, 5 gal/ hour at 1400 RPM, 7 gal/ hour at 1600 RPM, 9.5 gal/ hour at 1800 RPM.
Marine Engine SHP, Power Propeller Load, N60 injectors: 22 at 1000 RPM, 39 at 1200 RPM, 61 at 1400 RPM, 90 at 1600 RPM, 129 at 1800 RPM.
Fuel Consumption with above conditions: 2.75 gal/ hour at 1200 RP, 3.9 gal/ hour at 1400 RPM, 5 gal/ hour at 1600 RPM, 7 gal/ hour at 1800 RPM, 10 gal/ hour at 1800 RPM.
