Cummins ISX
Cummins ISX engine.

Five Cummins ISX15 engine service tips

Making sure you are using the latest part updates and installation techniques can prevent costly maintenance errors and even catastrophic engine failures.

A 25-year veteran of the manufacturing business, Egan Hernandez joined Industrial Parts Depot (IPD) of Torrance, CA, back in 2011.  He handles marketing and communications for IPD, which designs and manufactures a broad range of diesel & gas engine replacement parts for a wide variety of applications. In this guest column, he shares some repair tips IPD has compiled after taking care of Cummins ISX15 engines for trucking customers.

With a power range of 430-650 hp, they are workhorses for a variety of jobs.

But there have been a number of important updates and changes that could significantly impact parts selection and service procedures when servicing those engines – changes warrant attention, whether repairing an engine or performing a complete overhaul.

For example, there have been five different changes to the cylinder liner design so it’s very important that purchasing and service personnel are aware of the differences in engine designs and installation procedures when you service ISX engines – or severe problems can occur.

Potential problems include excessive engine parts wear, premature failures, avoidable downtime, and even catastrophic engine damage.

Here are five tips that can help truckers service and rebuild ISX15 eunits more accurately and efficiently, and in some cases with added savings of time and costs.

Choose updated critical parts: Cylinder kits are the heart of the Cummins ISX series engine overhauls. Many over-the-road users and engine rebuilders realize the importance of using cylinder kits that reflect the latest design updates. For example, the current update of original equipment (OE pistons for ISX15 (15-liter, single cam) engines features a special bushing-less design with a closed skirt that is specifically made to work with anti-polishing ring or “APR” cylinder liners.

Those are very significant design updates. So it’s important to choose a parts supplier that makes it a high priority to replicate OE updates for product lines when possible to ensure durability, endurance and interchangeability.

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. 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. There is also a special installation tool currently included with each engine kit order. The updated style APR cylinder liner 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.

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.

In fact, 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.

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 models, though, use two types of drilled rods – a saw-cut and a fractured type.

Those terms refer to the surfaces between the connecting rod and rod cap and am matching the connecting rod with the correct bearings is critical.

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. 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.

Press-in type camshaft bushings: On earlier-model 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 weights 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.

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 your Cummins ISX15 engines.

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