The engine is often referred to as the heart of the machine and must be cared for accordingly. It is not unusual to find that recommended engine oil and filter replacement intervals are adhered to only intermittently and haphazardly. Many mechanics are unaware that when they change the engine oil, as well as oil and fuel filters, they must also check and replace the coolant filters and crankcase breathers at the required intervals.
1. Replace Filters at Recommended Intervals
Remember to replace engine oils as specified for the application and grade.
Regular "off-the-shelf" engine oils must be replaced after 250 hours of operation, and it is good practice to replace the engine oil filters every time and the fuel filters every other time the engine oil is changed. There are severe-duty engine oils (such as: API CI-4 and ACEA E5-02) that can be stretched to 500 hours of operation. However, these oils are very expensive and customers shy away from using them.
2. Service the Cooling System
Most of today's high-performance diesel engines feature a coolant filter and require a specific DCA4 additive concentration in the coolant fluid. This additive builds up a protective coating in the entire cooling system that is important to avoid cavitations around the liner walls.
If this coating is missing, material starts to erode from the outer surface of the cylinder liner wall that is surrounded by the streaming coolant fluid. Such erosion can result in the development of pinholes through the entire liner wall. When coolant and antifreeze enter and dilute the engine oil, engine failure soon follows.
Coolant fluid should be checked every 500 hours to ensure that the prescribed DCA4 additive level is maintained.
3. Maintain Crankcase Breather Assembly
The crankcase breather assembly filters hot gases escaping from the crankcase. The filter insert (part of the breather assembly), separates the residual oil from the gases and returns it to the oil pan. The filtered gases are recycled through the combustion air intake system of the engine. If this filter insert is soaked with oil, plugged with solid particles or the crankcase breather housing is dented, the suction of the turbocharger will actually attempt to siphon engine oil out of the crankcase. Many mechanics mistake the developing smoke as a consequence of a failing turbo charger.
Additionally, if a malfunctioning crankcase breather is not replaced in time, the entire combustion air system will be coated with oil residue that may cause the after-cooler to become less effective, a problem that, over time, can cause the engine to overheat.
4. Check the Air Cleaner Daily
Operators should check the air cleaner indicator daily. Plugged-up air filter elements will cause the turbo charger to suck the air out of the crankcase, or the engine's fuel injection system may try to compensate for the lack of air with an increase in fuel injection, which will cause the engine to overheat and eventually fail.
To keep the engine healthy and productive for a long time, the air cleaner must be checked daily and the filter elements changed at the manufacturer's recommended exchange intervals-more often if the application requires.
4 Steps to Implementing a Successful Preventive Maintenance Program
- Strictly follow the OEM's recommendations. It should be company policy for each mechanic to read the safety and maintenance sections in the operation and maintenance manual, supplied with each unit.
- Participate in annual maintenance training.
- Establish a machine cleaning and inspection schedule that must be documented and adhered to. If severe, deficiencies should be corrected immediately, or if they can wait, deficiencies should be documented and corrected during the next machine service.
- Make the operator part of the maintenance team. A good operator should perform a walk-around inspection prior to each shift.
5. Fuel and Injectors
Government regulations regarding the gradual reduction of harmful emission gases and particles make it necessary to constantly redesign engines in order to comply with the prevailing U.S. Environmental Protection Agency (EPA) regulations.
One of the initial changes to the injection system was to reduce harmful emission gases by improving the combustion process. This was accomplished by increasing the fuel injection pressure, which produced improved atomization of the fuel-to-air mixture. However, the increased fuel pressure caused the injectors and fuel lines to wear out sooner, especially if the fuel supply is not absolutely clean.
It is recommended to check and replace fuel injectors every 3,000 hours of operation to avoid worn out and dripping injector nozzles, which can cause over-fueling and piston
6. Hydraulic System Maintenance
Today's hydraulic systems are self-contained and need little maintenance with the exception of an occasional filter change and hydraulic fluid replacement.
Replacing the hydraulic fluid and filters at the required intervals is the best prevention to avoid premature failure and expensive component repair. Owners and operators are best served when they monitor the hydraulic fluid by taking frequent oil samples. However, oil samples must be taken carefully and the oil analysis reports must be properly interpreted to be of value as a maintenance tool.
Also, it is good practice to fill and bleed hydraulic pumps or motors after replacement to prevent a dry run, which can destroy the component minutes after installation. This pre-filling procedure is especially important if a hydraulic component is installed above the hydraulic fluid level in the tank.
7. Use Proper Viscosity Fluid
Another problem that occasionally crops up is that customers do not always use the quality oils and viscosity grade recommended by original equipment manufacturers (OEMs). Hydraulic fluid with too low of a viscosity will cause excessive internal wear and lead to overheating that will harden and destroy seals and hydraulic hoses. As a result, the machine will start to leak and lose efficiency.
8. Adding Electrical Components
Jobsite conditions frequently require the installation of auxiliary electrical or electronic equipment, such as additional working lights or converters that require high amperage. Many times, such accessories are connected without checking the available maximum alternator output on the machine. For example, an excavator may be equipped with a 50-amp alternator; therefore, the maximum current draw of all electrical components combined must remain below the maximum alternator output.
Power supply (hot) wires are often spliced into what appears to be a hot wire or connected to a hot terminal. Electrical problems are often the direct result of such an installation. Most manufacturers make provisions for electrical accessories-check your machine manual prior to making a hasty electrical connection.
9. Inspect on a Regular Basis
Most machine or component failures could be completely avoided with a few preventive machine inspections. Structural cracks in particular can be detected most of the time in their initial stages at a time when corrective repairs and reinforcements are still possible.
Consider initiating a preventive maintenance program that includes steam cleaning the entire machine at reasonable intervals and performing a thorough visual inspection of all structures, especially attachments.
Most equipment manufacturers design their machines to be as user friendly as possible, but they also need to make their machines more efficient and productive. Because the later requirements are accomplished by integrating electronics and microprocessors, these machines have, throughout time, become more and more sophisticated and require a new maintenance approach. The service mechanic of today has to learn to use sophisticated electronic equipment and a laptop computer. Proper maintenance will ensure not only safe operation, but extended service life.
Construction Business Owner, October 2009
