There have been a number of important updates and changes that could significantly impact parts selection and service procedures when servicing Cummins ISX15 engines – Cummins’ most popular heavy duty engine, says Steve Scott, director, technical support, Industrial Parts Depot (IPD). These changes warrant attention, whether repairing an engine or performing a complete overhaul.
IPD (www.ipdparts.com) manufactures and distributes a broad range of replacement parts for Caterpillar, Cummins, Detroit Diesel, Volvo and Waukesha series engines.
There have been five different changes to the cylinder liner design, he notes. “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 fleets 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
Because cylinder kits are the heart of the Cummins ISX series engine overhauls, it is important to use cylinder kits that reflect the latest design updates. “Unfortunately,” observes IPD’s Scott, not all parts suppliers are in a position to keep up with the latest OE design changes.”
2. Use the special piston installation tool
Cummins ISX15 cylinder liners feature a removable APR (anti-polishing ring) that overhangs the liner bore. Its purpose is to remove carbon deposits from the upper portion of the piston.
The special piston installation tool helps prevent bore polishing – surface wear that damages the liner surface – of the liner walls, a situation that can result in a significant increase in oil consumption.
To use the tool, remove the APR from the liner, insert the tool and complete the piston installation, Scott explains. The tool prevents the piston rings from expanding into the APR groove, thus providing a smooth transition of the piston into the cylinder liner.
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, says IPD’s Scott.
The use of these plugs is important, he notes, because “most bearing manufacturers report that the presence of dirt or foreign objects in oil passages is a leading cause of bearing failure. 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
Scott points out Cummins ISX series engines use three different styles of connecting rods, making it critical to match the connecting rod with the correct 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.
The saw-cut connecting rod bearings 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,” he 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, he says.
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 in.) and weight of nearly 65lbs, says Scott of IPD. 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 in and also be 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,” he says.
“Considering the load that is 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, Scott says it is important to review and understand manufacturer updates and changes in order to select the correct parts for the specific application, and also to follow current procedures when servicing Cummins ISX15 engines.
