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Cummins ISM Engine

Cummins ISM Engines For Sale

Red Cummins ISM Engine on Top of a Black PlatformCummins ISM engines are at the forefront of the heavy-duty diesel engines in its class. The ISM undergoes thorough testing to ensure it meets the high standard Cummins demands for its products. The six-cylinder engine produces a range of horsepower from 280 to 450 hp. The ISM previously identified as the M11 CELECT plus but earned its ‘IS’ label in 1998 when it harnessed an Interact System. Each and every element of the Cummins ISM Engine is produced using the Six Sigma process, which ensures a high level of quality throughout each model.

Cummins designed the M11 ISM motor with drivers in mind. This is why the ISM provides coaching and feedback of trip data for the driver in order to aid in efficient and comfortable operation. Adding to this, the ISM benefits from a variable geometry turbocharger (CGT) meaning sharp throttle response and reduced turbo lag to help get loads moving.

ISM Engine Applications and Uses

Blue Logo of AERA

  • Transit Bus
  • Fire & Emergency
  • Heavy-Duty Truck
  • Motorhome & RV
  • Transit Bus

Common ISM Engine Problems & Failures

Below, you’ll find the most frequent engine problems and malfunctions encountered by costumers seeking to replace their Cummins ISM due to an engine failure. Unfortunately, some of these problems have the potential to cause irreparable damage to your M11 ISM motor. However, timely detection of others can result in effective remedies.Side View of a Red Cummins ISM Engine

  • Camshaft Failure
  • Crankshaft Failure
  • Lifter/Roller Failure
  • Connecting Rod Failure
  • Spun Crankshaft Bearings
  • Cracked Cylinder Head(s)
  • Scored Pistons and Liners
  • Over fueling
  • Lack of oil or oil pressure
  • Excessive Blow By
  • Dropped Valves

Cummins ISM Engine Replacement Options

When it comes to engine replacement, there are several options. In a worst case scenario, a failure that renders your ISM unsalvageable could force you into a complete engine replacement. However, some circumstances may only require you to replace some parts or components. Other circumstances can make a mere refresh the best choice. Of course, overall cost, time, and availability will likely play a part in your decision, so let us inform you of the pro’s and con’s of a new Cummins ISM engine from the dealer.

Replacement Option Chart of a Cummins ISM Engine

Remanufacturing Process

A remanufactured Cummins ISM long block is a great replacement for someone who has been the victim of an engine that has suffered a catastrophic internal engine failure, but luckily escaped with good re-useable external components. that can be salvaged from their old motor. A long blocks are is also a good alternative when trying to reduce costs in when faced with such an issue.

At Big Bear Engine Company, our team of machinists and engine builders come to perform a full core tear down, cleaning, inspection, and machining of the engine before it leaves our facility. to These processes ensure perfection the highest standards of quality are met each and every time we remanufacture and engine.

It is important to note that all of our Cummins ISM remanufactured long blocks are constructed using a combination of both reman and new parts. However, we do not recondition or refurbish former engine parts. Rather, we completely rebuild your old ISM motor to OEM specs.

Thorough Cleaning

Every Cummins M11/ISM motor is completely stripped. The block, head, rods, crankshaft and camshaft are comprehensively cleaned in a chemical jet wash or hot tank to get rid of any impurities that could lead to both early component and/or engine failure.


Prior to being thoroughly inspected by our quality control department, all crankshafts are precision machined to exact tolerances, polished, and magnafluxed.

Cylinder Head

The head is resurfaced both to ensure a proper sealing surface with the block and a finish consistent with today's new head gasket materials. Valve height is mic-d and every head is vacuum tested to assure accurate valve seating.

Cylinder Block

Blocks naturally develop imperfections over time. Therefore, we magnaflux each crankcase to carefully inspect for cracks and defects. Cylinders are then bored, honed and brought within precise tolerances. Torque plate honing is performed on some engines to prevent cylinder head distortion once the head is bolted in place and torqued to spec on the block. This process eliminates a major cause of engine blow-by. All block surfaces are machined and surveyed to ensure proper finish.


All ISM camshafts are carefully inspected and precisely machined to provide correct lift. Lobes are also measured with a micrometer to make certain that OEM tolerances are met.

Connecting Rods

Connecting rods are first cleaned, then machined to OEM specifications and honed to the standard diameter of original equipment for even distribution of stress on the bearings. New bushings are fitted and machined in all bushed rods. Additionally, each rod is carefully inspected for bend and twist.

New Parts

Our Cummins M11/ISM long block engines receive a standard set of new parts such as pistons and piston rings, bearings, gaskets and seals, and liners. These new parts guarantee excellent performance and consistency throughout the lifetime of the your Cummins ISM. The All new parts are a combination of both OEM and Aftermarket aftermarket parts when available.

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Remanufactured Engines Standards

The definition of remanufacture is to make something as close to new as possible—and that’s exactly what we do at Big Bear. Wearable parts are automatically replaced and all Cummins ISM  core material is thoroughly inspected and examined against the original equipment specifications to guarantee correct dimensional tolerances. Replacement parts are new or requalified. If new, parts are made in the same production procedures as the original equipment was. Testing is then carried out to manufacturer specifications and original production standards.

Reman ISM Long Block Parts List:

Red Cummins ISM Engine

  • Intermediate Cover
  • Timed Front Gear Group
  • New Upper and Lower Gasket Set
  • Complete, Loaded Cylinder Head
  • Crankshaft
  • Connecting Rods
  • Cylinder Block
  • Camshaft
  • Followers/Lifters
  • Pistons
  • Liners
  • Piston Rings
  • **1 Year Warranty

*Note: We can provide new oil pumps, oil coolers, water pumps, turbos, injectors and fuel pumps for additional cost with the long block, but the components will not come assembled to the engine.

**First 6 Months Parts & Labor, Second 6 Months Parts Replacement Only. Ask your sales representative for a full copy of our remanufactured long block warranty.

Cummins ISM Spec

Engine Data

ConfigurationInline 6 Cylinder
Displacement10.8 L, 661 cubic inches
Bore x Stroke4.921 in x 5.787 in
Cylinder HeadCast Iron
Engine BlockDeep-skirt, Cast Iron
Firing Order1-5-3-6-2-4
Compression Ratio16.3: 1
AspirationTurbocharged and intercooled

Back View of a Cummins ISM Engine

Give us a call today at 844-340-4114 for immediate sales and support for the Cummins ISM Engine, Cummins 4BT, Cummins 6BT, 6CT, ISC, 855, QSB 4.5 L or CAT 3306. If you have any questions check out our FAQ Page. We are always ready to help or just listen to your crazy off-roading adventures!

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