Cummins ISX11.9 CM2250 – Service Manual 000-999   Complete Engine – Overview

General Information

Concern has been generated at both the factory and in the field about engine failures that occur a short time after an in-frame repair. Analyses of the returned parts indicate many of the damaged parts are the result of dirt entering the engine during repair. In particular, investigation of the failure of ISX engine connecting rod and main bearings very soon after field repairs of the oil cooler, front cover, or cylinder head has shown that 30 percent of the failures are the result of contamination of some main oil drillings. Investigation into the type and source of the contamination indicates return engines are contaminated during engine repairs, due to oil passages not being plugged and cavities not be masked off to protect against contamination.

It is important that oil passages plugged and cavities are masked prior to scraping gaskets material and/or cleaning the joint surfaces. Good housekeeping that alleviates the amount of dust in the shop’s atmosphere is needed.   Washed parts that will not immediately be assembled into an engine, must be covered up to protect against contamination.   Regularly clean sockets, wrenches, gauges and containers used for engine repairs. Clean the work surfaces of carts, tool boxes and tables regularly to prevent contaminations of parts.

Review the General Cleaning Instructions in this manual. Field shops are strongly encouraged to review these instructions with all technicians and to include general cleaning instructions in technician training programs and new technician orientation programs.

Before servicing any fuel system components such as fuel lines, fuel pump, injectors, etc. which would expose the fuel system or internal engine components to potential contaminants prior to disassembly, clean the fittings, mounting hardware, and the area around the component to be removed. If the surrounding areas are not cleaned, dirt or contaminants can be introduced into the fuel system and engine, resulting in damage to the fuel system and engine. See the engine steam cleaning procedure in the service manual.

The modern fuel system plays a major part in reducing diesel engine emissions. In order for the fuel system to meet these ever-increasing expectations, the fuel system must more completely atomize injected fuel and the injection events must be precisely controlled. The internal drillings of a modern injector are often extremely small and very susceptible to plugging from contamination. Plugging of the injector on some diesel engine fuel systems cause a continuous fueling event that can result in engine damage. Modern diesel fuel injection systems can operate at very high pressures. High pressure fuel can convert simple particles of dirt and rust into a highly abrasive contaminate that can damage the high pressure pumping components and fuel injectors. Many modern injectors are nonserviceable, with the exception of the nozzle and control solenoid. Some injectors are completely nonserviceable.

• For engines under warranty, Cummins Inc. does pay to steam clean an engine before beginning repairs. When repairs must be performed in the field, determine if the customer has a steam cleaner available. If not, take ample amounts of electrical contact cleaner to the jobsite.
• Use electrical contact cleaner, rather than compressed air, to wash dirt and debris away from fuel system fittings. Diesel fuel on exposed fuel system parts attracts airborne contaminants.
• Choose lint free towels for fuel system work.
• Be aware of compressed air. Avoid or limit the use of compressed air for cleaning if there is a fuel system or major engine repair underway in close proximity.
• The word micron is the abbreviation for a micrometer, or one millionth of a meter. The micron rating is the size of the smallest particles that will be captured by the filter media. As a reference, a human hair is 0.09 mm [0.0038 in] in diameter. One micron measures 0.001 mm [0.00004 in]. There are many Cummins® engines that require secondary fuel filtration at the 3 micron level. These contaminants are far smaller than can be seen with the human eye, a magnifying glass, or a low powered microscope.

The tools used for fuel system troubleshooting and repair are often overlooked as a potential source of contamination. Like fuel system parts, if tools are coated with oil or fuel they are a magnet for airborne contaminants. Because a tool looks clean does not mean that it is clean. Remember the following points regarding your fuel system tools:

• Always keep your fuel system tools as clean as possible.
• Clean and dry the tools before returning them to your tool box.
• If possible, store fuel system tools in sealed containers. This also helps to keep tools organized and ready for the next service event.
• Make sure fuel system tools are clean before use, especially if they are shared tools.

Keeping a fuel system clean is easier than cleaning up and repairing a contaminated system. Once a fuel system is contaminated, it is nearly impossible to know if you have successfully removed the contaminants. Cap and plug fuel lines, fittings, and ports whenever the fuel system is opened, even if the repair is only going to take a short time to complete. Airborne contaminants can come from the next bay, from bumping the hood, or even from your clothing.

Potential contaminants can be dislodged from other parts being removed from the engine (even after the engine has been thoroughly cleaned) from accidental contact like bumping an engine cover or wiring harness. The best practice is to always cap and plug openings in the fuel system as soon as possible.

Rust, dirt, and paint can enter the fuel system whenever a fuel line or other component is loosened or removed from the engine. In many instances, a good practice is to loosen a line or fitting to break the rust and paint loose, and then clean off the loosened material.

When removing fuel lines or fittings from a new or newly-painted engine, make sure to remove loose paint flakes/chips that can be created when a wrench contacts painted line nuts or fittings, or when quick disconnect fittings are removed.

Before beginning repairs on a fuel system, be sure to understand the fuel flow of the particular engine. Information on engine fuel flows can be found in the service literature on QuickServe™ Online or in the printed service literature. Pay particular attention to the last point of filtration in the fuel system. After the last point of filtration, contaminants introduced into the fuel system have no possibility of being removed before entering contaminant-sensitive fuel system components.

A new Cummins® Virtual College course, titled Fuel System Clean Care, has been developed. This course, Number 1043, is located on the CD labeled GEN-13 of the Cummins® Midrange, Heavy Duty, and High-Horsepower Virtual College Libraries.

Cleaning products recommended and available from Cummins Inc. are listed in the table below.

If the engine is found to be magnetized, the engine will need to be disassembled and examined for:

• Engine inspection for electrical pass-through damage
• Magnetism of ferrous components
• Debris through the lubrication system
• Damage to bearings and bushings, including: crankshaft thrust bearings, main bearings, connecting rod bearings, and camshaft bushings
• Component or wear damage.

The Disassembly and Assembly sections of this manual can be used to disassemble and assemble the engine.

Measure each ferrous component with a gauss meter and record the results. If the magnetism is out of specification, the engine must be treated in general as if debris (fine particles) have been traveling throughout the lubrication system, resulting in wear and damage to components.

Components with measured gauss units greater than specification must be demagnetized or replaced. A facility capable of magnetic testing (Magnaflux) of the engine components is capable of demagnetizing (degaussing) components.

Check components in the lubrication system closely and thoroughly clean the oil galleries.

Replace all main bearings, thrust bearings, connecting rod bearings, and camshaft bushings.

NOTE: Do not attempt to demagnetize sensors, engine control modules, or actuators.

There are two methods for demagnetizing components:

• Passing the part through an alternating current coil (50 or 60 cycles per second)
• Passing a reversing, 30 point step-down current through the part.

The alternating current coil is suggested for smaller parts.

For larger mass parts, the reversing 30 point step-down is suggested.

Parts with acceptable levels of magnetization must be cleaned and inspected for reuse.

It is recommended to have the alternating current coil just large enough for the parts to pass through. A small part passed through a large coil will not be demagnetized as well as if it were passed through a smaller coil.

The coil must be located so the longest part axis of the part is perpendicular to the coil when passing through. Parts must pass through a minimum of 457.2 to 609.6 mm [18 to 24 in] beyond the coil for the most effective demagnetization.

Do not attempt to demagnetize small parts by loading them into a basket and passing the basket through a coil. Do not attempt to demagnetize a whole engine assembly.

Direct current demagnetization can be accomplished by using the magnetizing unit. Clamp the part between the head and tail stock. Activate the demagnetization controls, and the reversing, step-down current passes through the part. Check all parts with the gauss meter.

When tiny pits occur in clearly defined patterns, or surfaces are fluted, electric current can be the problem. The patterns will vary with metals, sources, and movement.

For insert bearings, pitting is a chief indication. In anti-friction bearings, such as ball bearings, fluted surfaces or wavy lines of pitting in patterns differing with rotation, vibration, and current are the chief indications.

Sources of electrical damage are:

• Electrically actuated components (such as a clutch)
• Static current from belts or other moving parts
• Grounding of electrical system through the crankshaft when some component such as the generator or engine block has not been grounded properly
• An improperly grounded 6 volt system.

Engines that have experienced dust outs because of intake air system component damage that resulted in cylinder liner and piston ring wear, must be treated as if the lubricating oil system has been contaminated with debris. The engine must be disassembled and cleaned appropriately to remove debris from the oil galleries, block cavities, cylinder head, and air intake system. Camshafts, rocker lever pins, and rollers must also be thoroughly cleaned and examined for wear.

The procedures required to replace an engine will vary with different engine models, the type of equipment, optional equipment, and the shop facilities. Use the following procedures as a guide. All replacement steps will not apply to all types of equipment. Complete only the steps that apply to the equipment involved. Use the equipment manufacturer’s recommendations and precautions for removal of chassis parts to gain access to the engine.		SMALL | MEDIUM | LARGE