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servicing Cummins® ISX15 engines

There have been a number of important updates and changes that could significantly impact parts selection and service procedures when servicing Cummins® ISX15 engines. This engine series has become a very popular power source for vocational applications.
With a power range of 430 to 650 hp, these changes warrant attention—whether repairing an engine or performing a complete overhaul.
“There have been five different changes to the cylinder liner design,” says Steve Scott, director of technical support for Industrial Parts Depot in Torrance, California. IPD manufactures and distributes a broad range of replacement parts for Caterpillar, Cummins, Detroit Diesel, Volvo, and Waukesha series engines. “It’s very important that purchasing and service personnel are aware of the differences in engine designs and installation procedures when they are servicing ISX engines—or severe problems can occur.”
Potential problems include excessive engine parts wear, premature failures, avoidable downtime, and even catastrophic engine damage.


Scott offers five tips that can help fleet specialists and engine rebuilders service Cummins ISX15 engines more accurately and efficiently, and in some cases with added savings of time and costs.

  1. Choose updated critical parts: Cylinder kits are the heart of the Cummins ISX series engine overhauls. Many engine rebuilders realize the importance of using cylinder kits that reflect the latest design updates. For example, the current update of OE pistons for ISX15 (15-liter, single cam) engines features a special bushingless design with a closed skirt that is specifically made to work with an anti-polishing ring (APR) cylinder liners.“These are very significant design updates,” says Scott. He adds that unfortunately, not all parts suppliers are in a position to keep up with the latest OE design changes and remain competitive. Scott explains that IPD makes it a high priority to replicate OE updates for product lines when possible to ensure durability, endurance, and interchangeability.
  2. Use the special piston installation tool: Cummins ISX15 cylinder liners feature a removable APR that overhangs the liner bore. “The purpose of this ring is to remove carbon deposits from the upper portion of the piston,” explains Scott. “This helps prevent bore polishing of the liner walls, a situation that can result in significantly increased oil consumption.” Bore polishing is surface wear that damages the liner surface. To use the piston installation tool, remove the APR ring from the liner, insert the special tool, and then proceed to complete the piston installation. The piston installation tool prevents the piston rings from expanding into the APR ring groove, thus providing a smooth transition of the piston into the cylinder liner. Scott says that IPD’s special installation tool is currently included with each IPD ISX15 engine kit order (a $149 OE value). He adds that the updated style APR cylinder liner from IPD is induction heat-treated includes a precision-honed ID, and has an OE-style APR carbon scraper ring. This liner also comes with a premium brass shim for ease of installation.
  3. Protect oil ports and passages from particulates: Replacement of gaskets is an integral part of every in-frame or out-of-frame engine overhaul. When it comes to servicing ISX series engines, complete gasket sets should also contain a number of small plugs that are used to protect the oil ports of the cylinder head, as well as the cylinder block, from dirt or other debris. “This is an important procedure to follow,” says Scott, “in fact, most bearing manufacturers report that the presence of dirt or foreign objects in oil passages is a leading cause of bearing failure,” Scott adds that there is also the danger of debris entering the cylinder head ports and interfering with the camshaft and upper bushings.
  4. Choose the correct style of connecting rod bearings: Cummins ISX series engines use three different styles of connecting rods, making it vital to use the proper type of bearings when replacing these parts. The early engines use non-drilled rods, which do not have an oil passage running through the connecting rod. Later engines use two types of drilled rods: a saw-cut type and a fractured type. These terms refer to the surfaces between the connecting rod and rod cap.

    “Matching the connecting rod with the correct bearings is critical,” says Scott. The saw-cut connecting rod bearings (big end) are composed of an upper and lower bearing shell. The shells are marked according to their proper locations, and feature tabs that are slightly offset.“This bearing shell design does leave room for installation errors,” Scott says. “In fact, it is possible to install them incorrectly and still be able to bolt the rod onto the crankshaft. If this happens, the rod will not get the needed oil supply and the engine will fail.”The fractured type of rods also requires upper and lower bearing shells, but due to the design cannot be installed incorrectly.
  5. Press-in type camshaft bushings: On earlier ISX dual cam engines, the injector camshafts are massive compared to the valve camshaft, with a journal diameter of 85 mm (3.346 inches), and weighs almost 65 lbs. While it may be a common practice to drive the camshaft bushings in for other engines, installation instructions specify that the cam bushings (injector and valve) need to be pressed in (rather than driven), and also pre-lubricated. According to several cylinder head rebuilders, due to the size and amount of retention (crush) holding the injector camshaft bearings in place, the bushings cannot be driven in without distorting or otherwise damaging them, which can lead to bushing failure when the engine is put into service.

Scott notes that considering the load that’s placed on the injector camshaft bushings, the timing for pressurized lube oil to reach the bushings (via the large oil port inside the camshaft) is critical.
In summary, it is important to review and understand manufacturer updates and changes in order to select the correct parts for your specific application, and also to follow current procedures when servicing Cummins ISX15 engines.


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