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Cummins ISL (8.9 L) Engine Program

8.9L Cummins ISL Engines For Sale

Side View of a Red 8.9L Cummins ISL Engine for Sale on Top of a Wooden Platform

Taking what it learned with the time-tested L10 (which gradually grew into the M11), the Cummins ISL was developed. It was originally launched for municipal buses in 1999, the engine itself being designed to fill the void left by the discontinued L10. Despite this, its characteristics align more so with the ISC. The ISL would quickly prove to be a wildly successful medium-duty engine, one that has now been in production (in one form or another) for more than 20 years. Not only was the Cummins 8.9L ISL more than 300 pounds lighter than its L10 predecessor, but it was also more powerful. Additionally, durability has always been one of the ISL engine’s strong suits, with a 500,000-mile service life being the norm when properly maintained.

Strong Foundation

Essentially a stroked 8.3L, the Cummins ISL boasts a crankshaft that provides a torque-friendly 5.69-inches stroke. One look at the ISL’s torque ratings and you’ll find that it was designed to produce big twist at low rpm, with peak torque being deliverable between 1,200 and 1,400 rpm. To hold up to the immense cylinder pressures that come with exceptional low-rpm torque, the Cummins ISL utilizes a high tensile strength, forged-steel crankshaft, forged-steel connecting rods, and two-piece steel pistons. Up top, the cast-iron 24-valve cylinder head remains glued to the block by way of six head bolts being employed per cylinder.


Two different injection systems have graced the ISL over the years, the first of which was the Cummins accumulator pump system (CAPS). In the CAPS arrangement, the injection pump is electronically controlled while the fuel injectors are mechanical. Beginning in 2003—and due to tightening particulate matter emissions regulations—Cummins made the change to high-pressure common rail (HPCR). The modern age HPCR system, which is still in use today, brought full-on electronic control into the equation for more precise fueling events. As for emissions equipment, despite the CAPS-equipped ISL engines never having to face the prospect of EGR, a DPF or SCR emissions technology, Cummins engineered the ISL platform to be adapted to meet the ever-increasing NOx and PM emissions of the time. All HPCR engines would eventually be fitted with EGR, DPF and SCR systems.

Highly Versatile

Due to the size, relative light weight and power output of the Cummins ISL, it has enjoyed high demand throughout its production history. In the medium-duty truck segment, you can find an ISL humming away in everything from dump trucks to refuse trucks. And in the world of transit buses and motorhomes it’s a popular power plant as well. In the latter category, the 425 hp ISL425 all but earned legendary status in motorcoach applications, where it’s renowned for its reliability, grade-climbing ability, and fuel efficiency. The ISL is also a favorite in the fire and emergency sectors.

Cummins ISL Engine Applications and Uses

  • Logo of AERA Engine Builders AssociationTransit Bus
  • Fire & Emergency
  • Medium-Duty Truck
  • Motorhome & RV
  • Motorcoach
    • Concrete Mixers

Common ISL Cummins Engine Problems & Failures

Listed below are some engine problems and failures commonly reported by customers who wish to replace their worn out or problematic Cummins ISL. Unfortunately, some of the issues listed below could lead to permanent damage of your engine, but some can be rectified if caught in their infancy.
Red 8.9L Cummins ISL Engine for Sale Wrapped with a Plastic on Top of a Wooden Platform

  • 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
  • Extreme Blow By
  • Dropped Valves

ISL Cummins Replacement Options

When it comes to the health of your engine, there could be an overabundance of complications. Worst case scenario, you could be left with an issue where your choices are limited exclusively to replacement. However, less stressing situations may just require you to replace some parts or components, or maybe your Cummins ISL just needs a new lease on life, requiring no more than a mere refreshment. Of course, cost, time, and availability will determine your decision, so let us inform you of the pro’s and con’s of a new Cummins ISL engine from the dealer as opposed to a used or reman long block option.

Replacement Options for 8.9L Cummins ISL Engine for Sale

Back View of a Red 8.9L Cummins ISL Engine for Sale on Top of a Wooden PlatformCummins ISL 8.9L Remanufacturing Process

A remanufactured Cummins ISL long block is a great replacement for someone who has experienced catastrophic internal engine failure but still has good, reusable external components that can be saved from the old engine. Long blocks are also a good alternative when trying to reduce costs in the hunt for a new engine.
Our team of machinists and engine builders perform a full-core tear down, cleaning, inspection, and machining of the engine before it leaves our facility to ensure perfection each and every time.
It is important to mention that all of our Cummins ISL remanufactured long blocks are constructed with a combination of both reman and new parts. However, we do not recondition or refurbish former engine parts but rather completely rebuild the old ISL engine back to OEM specs.

Thorough Cleaning

First, every ISL engine is wholly stripped. The block, head, rods, crankshaft and camshaft are thoroughly cleaned in a chemical jet wash or hot tank to remove all impurities that could accelerate both early component and engine failure.


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

Cylinder Heads

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

Cylinder Blocks

Blocks consist of magnetic particle which are inspected for cracks and imperfections. Cylinders are then bored and honed and inspected to precise tolerances. Torque plate honing is performed on particular engines to avoid the chances of cylinder head distortion after the head is attached and torqued to the block. This process eliminates a major cause of engine blow-by on Cummins ISL engines. Block surfaces are machined and then inspected to ensure proper finish.


Camshafts are carefully inspected and precisely machined to provide correct lift. Lobes are measured with a micrometer to make sure OEM tolerances are met.

Connecting Rods

Connecting rods are first cleaned, then machined to OEM specifications, taking care to hone them to the standard diameter of previous equipment (for even distribution of stress on the bearings). New bushings are fitted and machined in all bushed rods. Every rod is carefully inspected for bend and twist.

New Cummins ISL Parts

Our ISL long block engines receive a standard set of new parts such as pistons and rings, bearings, gaskets and seals, and liners. These new parts assure good performance and reliability throughout the lifetime of your engine. The new parts are a combination of OEM and aftermarket, when available.

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Please fill out the form below with your information and request. A member of our staff will be with you shortly.

Remanufactured Engine Standards

To remanufacture is to make as close to new as possible. Wearable parts are automatically replaced.

All Cummins 8.9 ISL core material is thoroughly inspected and examined against original equipment specifications for correct dimensional tolerances. Replacement parts are new or re-qualified. If new, parts are made in the same production processes as original equipment. Testing is performed to manufacturer specifications and original production standards.


Reman ISL Long Block Parts List:

Front View of a Red 8.9L Cummins ISL Engine for Sale on Top of a Wooden Platform

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

*Note we can provide new oil pumps, oil coolers, water pumps, turbos, injectors and fuel pumps for an additional cost with the long block but will not come assembled to the engine. In addition to diesel ISL engines, we also provide natural gas ISLG 8.9 L replacements.

**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 ISL Spec

Engine Data

Engine TypeFour Stroke, In-Line, Six Cylinder, Turbocharged/Charge Air Cooled
Displacement8.9 L  (541 ci)
Bore4.49 in (114 mm)
Stroke5.69 in (145 mm)
Compression Ratio16.6:1
Horsepower280 - 400 HP
Torque Range700 to 1255 ft-lbs
Weight (Dry)706 KG
Cylinders6 Inline
Cylinder Head MaterialCast Iron
Engine Block MaterialCast Iron, Removable Liners
Give us a call today at 844-340-4114 for immediate sales and support for the 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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