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The chart below shows the most common questions asked by owners of Detroit Diesel® engines 3-71 natural 4 valves 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 3-71 natural 4 valve Owner's operating or service manual.

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Engine will not start Lack of air intake or restricted air intake
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 3-71 Usefull Information 

The 371 Detroit Diesel is a relatively small but reliable engine. Finding parts can be difficult, but not with Diesel Pro. We have a huge selection of parts ready to be shipped virtually anywhere in the world. Our website is designed to offer multiple shipping options, including next-day air. We offer fast order processing, less than one business day, to get your parts to you faster than many other sources. We are fully equipped to ship internationally quickly and seamlessly as well, so if you have problems with a generator in the Yukon of Canada, or need to repair a boat in the Caribbean, we can get you what you need. Be sure to check out our cylinder kit, which is one of our best sellers for this engine, and will come with everything you will need for the overhaul, including rings, retainers and liners. Whatever you need, give us a call and we will be happy to get an order started for you. Try us today and you will see, Diesel Pro is a better way to buy parts online.

If you are unsure that this is your engine, locate the model and serial number stamped on the engine block. For this series, this number will start with a 3A, and be similar to 3A12345. Older models may have a marking that starts with 371, such as 371-12345 or a serial number that starts with a 3-, such as 3-12345.

This engine is also called the GM 371 in some uses.

General Specs, Information and Horsepower

Listed here are the 3-71 Detroit Diesel specs. Please note that torque is based on rated power at 85 degrees F, and horsepower is based on brake horsepower.

The Detroit Diesel 371 is a 3 cylinder engine with a total displacement of 213 cubic inches and has 4 main bearings.

Normal lubricating oil pressure is 30-60 PSI at 1200 RPM, 38-60 PSI at 1800 RPM and 40-60 PSI at 2000 RPM.

With N60 Injectors:

Horsepower (BHP): 66 at 1200 RPM, 84 at 1600 RPM, 97 at 2000 RPM.

Torque (LB FT): 287 at 1200 RPM, 277 at 1600 RPM, 252 at 2000 RPM.

With N70 Injectors:

Horsepower (BHP): 65 at 1200 RPM, 90 at 1600 RPM, 111 at 2000 RPM.

Torque (LB FT): 272 at 1200 RPM, 294 at 1600 RPM, 288 at 2000 RPM.

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