Written By, Mike McGlothlin
Cummins ISB 24-Valve
Replacing The 6BT
To meet more stringent U.S. emission regulations, the 6BT evolved into the Cummins ISB 24-Valve in 1998. The Interact System, B series engine (i.e. ISB) featured electronic control in the form of a Bosch VP44 injection pump. It also came equipped with a 24-valve cylinder head, a revised block, and a host of other changes. The implementation of 4-valve (per cylinder) head technology improved engine airflow and played a key role in decreasing NOx production. The original 5.9L ISB engine debuted midway through the 1998 model year in Dodge Ram 2500 and 3500 trucks. For the 2003 model year, the ISB gained high-pressure common-rail injection and complete electronic control (injectors and injection pump).
Common Applications
There is no question that the Cummins ISB 24-Valve is best-known for its use in Dodge Ram ¾-ton and larger pickup trucks, and to be sure most of the ISB engines produced during the ISB’s run were shipped to Chrysler. However, the ISB 5.9L became a mainstay engine in various other vehicles. School buses and transit buses were regularly equipped with the 24-valve 5.9L Cummins and, though smaller than its ISC cousin, the ISB was a fairly popular option in motorhomes. Many medium duty vehicles such as box trucks and single axle dump trucks relied on ISB propulsion, too, as did a host of step van applications. Across all these applications, operators frequently reference Cummins ISB specs to evaluate reliability and output.
A 9-Year Production Run
Throughout the course of its manufacturing cycle, demand for the Cummins ISB grew in leaps and bounds. For Dodge trucks alone, somewhere between 400,000 and 500,000 24-valve 5.9L engines were built for ’98.5-’02 model year Rams. It’s estimated that as many as 750,000 common-rail ISB’s were shipped to Ram for use in its ’03-’07 trucks. In 2007, Cummins built its 1.5 millionth 5.9L engine for Chrysler (production which began in 1988 and that included both the 6BT and ISB platforms). Engines supplied to the automaker were assembled at Columbus Midrange Engine Plant in Indiana (CMEP), but the ISB was also produced in Rocky Mount, North Carolina, Sao Paulo, Brazil, and Darlington, England. Both the VP44 and common-rail generations of the 24 Valve Cummins continue to be widely supported thanks to high production volume.
Why It’s Hard To Beat
Like the 6BT Cummins that came before it, the ISB 24-valve engines are quality, hard-working power plants that have proven very durable over the years. They return good fuel economy and turn out solid horsepower figures, especially in high-pressure common-rail form. An added bonus is that the ISB is a pre-emissions engine. Throughout its production, it was void of the problematic EGR and DPF systems that began to infiltrate Cummins engines in 2007. Last but not least, Cummins’ ISB 24-valve saw high production volume. Core parts and components are plentiful and the ISB enjoys tremendous aftermarket parts support. Trust us, these engines will continue to be around a while.
Sources:
A Dodge/Cummins Turbo Diesel Historical Perspective
-Turbo Diesel Registry, PDF
Big Bear Engine Company
https://www.4btengines.com/cummins-isb24-valve-engine-for-sale/
Cummins
www.cummins.com
Trucking Info
https://www.truckinginfo.com/93694/cummins-ships-dodge-ram-engine-no-1-million
Work Truck Online
https://www.worktruckonline.com/83860/cummins-builds-2-millionth-pickup-engine-for-chrysler
