Find the most frequently asked questions and Tips pertaining to Cummins, Cummins Power Generation and Onan equipment. If you’re experiencing continuing difficulties with your equipment we suggest letting a qualified technician resolve the problem. You can also find owners manuals, engine dataplate information and maintenance parts listings at Cummins QuickServe Online.



Dodge Engine    Engines ISB, ISC, ISM, N14    Alternative Fuel/Power Engine Information (Natural Gas, Propane, Fuel Cell)    How To Interpret The Cummins Engine Names (i.e. ISX, ISL, QSX15)   

Engine Series

IS = Interact System (i.e. ISX, ISB)
Q/QS = Signifies that an industrial engine is electronically controlled. QS stands for QUANTUM SYSTEM CONTROLS
B = B series engine line, includes 3.3 , 3.9, 4.5 and 5.9 liter engines. Offered in both fully mechanical and electronic models. 5.9 liter engine is available in both industrial and automotive versions.
C = C series engine line, includes only 8.3 liter engines. Offered in both fully mechanical and electronic models, industrial and automotive versions available.
E = On older engine models this meant the engine was electronic. EXAMPLE: K2000E
K = K series engine line, includes 19, 23, 38, 45, 50 and 60 liter engine models.
L = L series engine line, includes older 10 liter and current 9 liter engine models. Industrial and automotive versions available.
M = M series engine line, includes M11, 11liter engines only. Industrial and automotive versions available.
N = N series engine line, no longer being produced for U.S. market. Included NTA855 and N14 engine series. Industrial and automotive versions available.
T = T series engine line such as the QST30.
X = X series engine line, includes 15 liter engines only. Industrial and automotive versions available.

Engine Technology

If a number comes first in the engine name it represents the number of cylinders (i.e. 4BTAA3.9)
3.3 , 3.9, 4.5 and 5.9 = Liters of the engine
A= Water aftercooled. Will always be written as TA after the number of cylinders and an engine model letter. EXAMPLE: 4BTA3.9-P110
AA = Air to air after cooling AKA charge air cooling. EXAMPLE: 4BTAA3.9-P110
NA = Naturally aspirated
T = Turbo in any mechanically controlled engine (A-6CTAA8.3). On the QST30 the T is the actual engine model.
I/IS = Signifies that an automotive engine is also electronically controlled. The "I" was adopted to represent all versions of automotive electronic controls.

Why Buy A Diesel?   


Torque: The ISB typically has over 60% more torque capability than the gas alternative (Max 660 lb.-ft). The ISC typically has over 120% greater torque capability than the gas alternative (Max 1050 lb.-ft).

Horsepower at Altitude: Turbocharged Diesels are rated at 10,000 ft with no loss of power. Typical gas engines will lose 3% of power every 1000 ft in altitude. (E.g. a 290 hp has would deliver only about 200hp at 10,000ft, while a C8.3 300hp engine would still deliver 300hp)

Fuel Economy: Diesel engines typically get 50-100% better fuel mileage than gasoline engines due to lower engine speeds, high compression ratio, advanced combustion technology, and the higher energy content of diesel fuel vs. gasoline.

Exhaust Brake Capability: Exhaust brakes provide improved braking capability, improved safety, and lower maintenance costs. Not used with gas engines due to much lower compression ratios.


Advanced diesel technology makes a diesel engine last up to 3 times as long as comparable gas engines due to:

Lower piston speeds
Larger bearing surfaces
Piston Cooling
Gear driven camshaft instead of chain driven
Internal Engine Oil Cooler
Up to 50% Fewer External Parts

ISB is rated up to 52,000 lbs. GVW with a projected life-to-overhaul of 400,000 miles.
ISC is rated up to 80,000 lbs. GVW with a projected life-to-overhaul of 500,000 miles.

Diesel…a powerful advantage over gasoline

First, consider the two key factors for judging engine performance…horsepower and torque.

Horsepower determines how fast your vehicle can go, and how well it handles the hills. Torque, measured in pound-feet (lb-ft), determines how quickly your vehicle accelerates from a stop or passes another vehicle. Put simply, torque is what gets you going, and horsepower is what keeps you going…down the road.

Compared to a gasoline engine, a Cummins diesel engine will deliver peak torque quicker, for superior pulling power…especially when towing. And that’s just one reason why a Cummins diesel engine is the power of choice in hardworking vehicles.

At 230 horsepower, a gasoline engine delivers only 390 lb.-ft of torque. But a Cummins B5.9 engine at 230 horsepower really flexes its muscle with 605 lb-ft of torque. And for even greater power, Cummins C8.3 diesel engines are available up to 350 horsepower with 1050 lb.-ft of torque. That’s the kind of strength you can really feel working for you.

Easier Maintenance

Cummins engines have a simpler, more efficient design than gasoline engines. They have fewer parts, which means less to go wrong. In fact, Cummins diesels require fewer oil changes and maintenance intervals than gasoline engines. Over the life of your diesel, your maintenance frequency will be 40-50% less than gasoline engines. In short, you’ll spend more time on the road, and less time in the shop.

Fuel Economy

Diesel engines have always been designed and built to deliver the most work from the least amount of fuel. That means when a Cummins diesel engine is working its hardest, you’re saving the most…up to 75% in fuel costs. Bottom line…they are by far more efficient than gasoline engines.

The higher compression ratio and advanced combustion technology of Cummins diesel engines extract more energy from every drop of diesel fuel. So with every mile you drive, you’re saving on fuel. And that means you’ll save money while spending less time at the pump.


Greater durability allows diesel manufacturers to offer longer warranties. The typical diesel engine warranty is 5 years and at least 100,000 miles, while the typical gas engine warranty is 3 years / 36,000 miles.

Diesel engines provide longer maintenance intervals. Typical recommendation is 15,000 miles vs. 3 months or 3000 miles for gasoline engines.

Cummins offers the QuickServe program as well. QuickServe is a program that offers you an entire service network geared to providing rapid response with the highest quality service expertise in the industry. Our mobile QuickServe team:
• Provides you with a toll-free 800 number to call, staffed 24 hours a day, seven days a week.
• Calls you back with a comprehensive service plan within 30 minutes.
• Dispatches a mobile QuickServe truck and technician within four hours to your site.
• Provides a complete diagnosis within one hour of arrival.
• Completes most repairs within 24 hours.

Routine Maintenance Recommendations   

Check coolant level daily -

  • Change coolant filter every 80,000 km [50,000 mi], 1500 hours or 1 yr.  
  • Drain and flush system every 6000 hours or 3 yrs. and refill with heavy-duty coolant 50/50 mix of water and antifreeze.  
  • If Fleetguard's ES Coolant and ES filters are used, check chloride, sulfate, and pH levels according to Service Bulletin 3666209 to determine whether the coolant must be replaced.  
  • Always use antifreeze. In addition to freeze protection, antifreeze is essential for overheat and corrosion protection.  
  • The supplemental coolant additive (SCA) is required with Signature and ISX.
Check lubricating oil level daily -
  • Replace oil filter at every oil drain interval.  
  • Fleetguard Filter LF-9000 (Cummins Part No. 3406810)  
  • Use only high quality multigrade oil which meets Cummins Engineering Standards (CES) 20071 or CES 20076, such as Cummins Premium Blue® or its equivalent, in Cummins engines.
Synthetic Oil -
  • Synthetic oil may be used provided it meets performance and chemical requirements. However, the use of synthetic oil does not justify extended oil change intervals.
Other Fuel Additives -
  • Any fuel additive product should be accompanied with performance data supporting its performance and benefit. Engine failures caused by incorrect fuel are NOT covered under warranty. It is not the policy of Cummins to test, approve or endorse any product not manufactured or sold by Cummins.
Excessive Idle -
  • Should be avoided when possible and can result in reduced fuel economy and increased engine wear. An automatic shutdown feature is available. Contact a Cummins distributor for details.
Engine Warm-up -
  • Do not operate at full speed/load until coolant temperature reaches normal operating range.  
  • Do not operate above low idle until oil pressure is indicated.
Engine Cooldown -
  • Prior to shutdown, an engine should be idled 3-5 minutes after extended full throttle or high power operation. However, under normal driving conditions, such as exiting a highway, engine operation is generally lighter in nature and thereby, the 3-5 minute cooldown is not necessary.  
  • Cummins recommends the use of ASTM No. 2 diesel fuel.  
  • The use of No. 2 diesel fuel will result in optimum engine performance. At operating temperatures below 32° F (0° C), acceptable performance can be obtained by using blends of No. 2 D and No. 1 D. The use of lighter fuels can reduce fuel economy. The viscosity of the fuel MUST be kept above 1.3 cSt at 212° F (100° C) to provide adequate fuel system lubrication.
Other Recommendations -
  • Fuel-water separator should be drained daily  
  • Fuel filter replacement at 80,000 km [50,000 mi], 1500 hours or 1 yr. Fleetguard fuel filter
  • Fleetguard Fuel Filter # FS 1007 (Cummins Part No.3331096

Marine Engine FAQs