Reduced hours of operation at full load will result in a lower average power demand. A decreased average power demand should increase both the engine service life and the overhaul interval.
The need for an overhaul is generally indicated by increased fuel consumption and by reduced power.
The following factors are important when a decision is being made on the proper time for an engine overhaul:
Oil consumption, fuel consumption, and maintenance information can be used to estimate the total operating cost for your Caterpillar engine. Oil consumption can also be used to estimate the required capacity of a makeup oil tank that is suitable for the maintenance intervals.
Oil consumption is in proportion to the percentage of the rated engine load. As the percentage of the engine load is increased, the amount of oil that is consumed per hour also increases.
The oil consumption rate (brake specific oil consumption) is measured in grams per kW/h (lb per bhp). The brake specific oil consumption (BSOC) depends on the engine load. Consult your Caterpillar dealer for assistance in determining the typical oil consumption rate for your engine.
When an engine's oil consumption has risen to three times the original oil consumption rate due to normal wear, an engine overhaul should be scheduled. There may be a corresponding increase in blowby and a slight increase in fuel consumption.
A planned overhaul before failure may be the best value for the following reasons:
If a major engine failure occurs and the engine must be removed, many options are available. An overhaul should be performed if the engine block or the crankshaft needs to be repaired.
If the engine block is repairable and/or the crankshaft is repairable, the overhaul cost should be between 40 percent and 50 percent of the cost of a new engine with a similar exchange core.
This lower cost can be attributed to three aspects:
To minimize downtime, a scheduled engine overhaul by your Caterpillar dealer is recommended. This will provide you with the best cost/value relationship.
Note: Overhaul programs vary according to the engine application and according to the dealer that performs the overhaul. Consult your Caterpillar dealer for specific information about the available overhaul programs and about overhaul services for extending the engine life.
If an overhaul is performed without overhaul service from your Caterpillar dealer, be aware of the following maintenance recommendations.
Clean the fuel injector body and replace the O-rings. Replace the O-rings and the gasket on the injector sleeve. Clean the area around the injector seating in the injector sleeve. Refer to the Service Manual for the complete procedure, or consult with your Caterpillar dealer for assistance.
These components should be inspected according to the instructions that are found in various Caterpillar reusability publications. The Special Publication, SEBF8029 lists the reusability publications that are needed for inspecting the engine parts.
If the parts comply with the established inspection specifications that are expressed in the reusable parts guideline, the parts should be reused.
Parts that are not within the established inspection specifications should be dealt with in one of the following manners:
Parts that do not comply with the established inspection specifications can result in the following problems:
Reduced engine efficiency and increased fuel consumption translates into higher operating costs. Therefore, Caterpillar Inc. recommends repairing out-of-spec parts or replacing out-of-spec parts.
The following components may not last until the second overhaul.
Caterpillar Inc. recommends the installation of new parts at each overhaul period.
Inspect these parts while the engine is disassembled for an overhaul.
Inspect the crankshaft for any of the following conditions:
Check the journal taper and the profile of the crankshaft journals. Check these components by interpreting the wear patterns on the following components:
Note: If the crankshaft is removed for any reason, use the magnetic particle inspection process to check for cracks in the crankshaft.
Inspect the camshaft for damage to the journals and to the lobes.
Note: If the camshaft is removed for any reason, use the magnetic particle inspection process to check for cracks in the camshaft.
Inspect the following components for signs of wear or for signs of scuffing:
Caterpillar Inc. recommends replacing the crankshaft vibration damper.
During an overhaul, the removal of the oil cooler core and the aftercooler core is recommended. The oil cooler core and the aftercooler core should be cleaned and pressure tested.
Do not use caustic cleaners to clean the core.
Caustic cleaners can attack the internal metals of the core and cause leakage.
The concentration of supplemental coolant additive (SCA) should be checked regularly with test kits or with S·O·S Coolant Analysis (Level 1). Further coolant analysis is recommended when the engine is overhauled.
A coolant analysis can be conducted in order to verify the condition of the water that is being used in the cooling system. A full water analysis can be obtained by consulting your local water utility company or an agricultural agent. Private laboratories are also available for water analysis.
Caterpillar Inc. recommends an S·O·S Coolant Analysis (Level 2).
An S·O·S Coolant Analysis (Level 2) is a comprehensive coolant analysis which completely analyzes the coolant and the effects on the cooling system. An S·O·S Coolant Analysis (Level 2) provides the following information:
S·O·S Coolant Analysis (Level 2) provides a report of the results of both the analysis and the maintenance recommendations.For more information about coolant analysis, consult your Caterpillar dealer.