0325038 JOHNSON SHIM

Illustration 1 g00745964
(Y) Cost
(X) Time
(1) Cost of maintenance and repair that is planned
(2) Cost of maintenance and repair that is not planned In Illustration 1, line (1) represents the maintenance and repair costs for an owner that followed the recommendations for inspection, maintenance, and repair. The peaks represent overhauls.Line (2) represents the maintenance and repair costs for an owner that chose to operate beyond the recommended intervals. The initial cost of the “repair-after-failure” philosophy is lower. Also, the first overhaul was delayed. However, the peaks are significantly higher than the peaks for the customer that used the “repair-before-failure” philosophy .The higher peaks result from two key factors:
Delaying an overhaul until a breakdown increases the chance of a catastrophic failure. This type of failure requires more parts, labor, and cleanup.
Excessive wear means that fewer components will be reusable. More labor may be required for salvage or repair of the components.When all of the costs are considered, “repair-before-failure” is the least expensive alternative for most components and engines.It is not practical to wait until the engine exhibits symptoms of excessive wear or failure. It is not less costly to wait. A planned overhaul before failure may be the best value for the following reasons:
Costly unplanned downtime can be avoided.
Many original parts can be reused according to the guidelines for reusable parts.
The service life of the engine can be extended without the risk of a major catastrophe due to engine failure.
Achieve the best cost/value relationship per hour of extended service life.Overhaul Intervals
Some factors that are important for determining the overhaul intervals include the following considerations:
Performance of preventive maintenance
Use of recommended lubricants
Use of recommended coolants
Use of recommended fuels
Proper installation
Operating conditions
Operation within acceptable limits
Engine load
Engine speedGenerally, engines that are operated at a reduced load and/or speed achieve more service life before an overhaul. However, this is for engines that are properly operated and maintained.Other factors must also be considered for determining a major overhaul:
The total amount of fuel consumption
The service hours of the engine
An increase of oil consumption
An increase of crankcase blowby
The wear metal analysis of the lube oil
An increase in the levels of noise and vibrationAn increase of wear metals in the lube oil indicates that the bearings and the surfaces that wear may need to be serviced. An increase in the levels of noise and vibration indicates that rotating parts require service.Note: It is possible for oil analysis to indicate a decrease of wear metals in the lube oil. The cylinder liners may be worn so that polishing of the bore occurs. Also, the increased use of lube oil will dilute the wear metals.Monitor the engine as the engine accumulates service hours. Consult your Caterpillar dealer about scheduling a major overhaul.Note: The driven equipment may also require service when the engine is overhauled. Refer to the literature that is provided by the OEM of the driven equipment.Using Fuel Consumption For Calculating the Overhaul Intervals
The total fuel consumption is the most important factor for estimating the overhaul interval. Fuel consumption compensates for the application and for the engine load.If the total fuel consumption has not been recorded, use the equation in Table 1 in order to estimate the hours until the overhaul. The equation may also be used to estimate overhaul intervals for new engines.
Table 1
Equation For Calculating Overhaul Intervals
H = F/R
“H” is the number of estimated hours until the overhaul interval.
“F” is the estimated total amount of fuel consumption of the engine.
“R” is the rate of fuel consumption in liters per hour or gallons per hour. Use the actual records of fuel consumption, when possible. If the actual records are not available, use the following procedure in order to estimate the fuel consumption.
Estimate the average percent of the load for the operation of the engine.
Refer to the engine's Caterpillar, "Engine Specifications" (“spec” sheet). This will determine the fuel consumption for the percent of the load that was estimated in Step 1. Use this figure for the equation in Table 1. Oil Consumption as an Overhaul Indicator
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.Overhaul Inspection
Refer to the Service Manual for the disassembly and assembly procedures that are necessary in order to perform the required maintenance on the items that are listed. Consult your Caterpillar dealer for assistance.To determine the reusability publications that are needed to inspect the engine, refer to Guidelines for Reusable Parts and Salvage Operations, SEBF8029, "Index of Publications on Reusability or Salvage of Used Parts".The Guidelines For Reusable Parts and Salvage Operations is part of an established Caterpillar parts reusability program. These guidelines were developed in order to assist Caterpillar dealers and customers reduce costs by avoiding unnecessary expenditures for new parts. If the engine parts comply with the established inspection specifications, the parts can be reused.The use of out-of-spec parts could result in unscheduled downtime and/or costly repairs. The use of out-of-spec parts can also contribute to increased fuel consumption and reduction of engine efficiency. New parts are not necessary if the old parts can be reused, repaired, or salvaged. Otherwise, the old parts can be replaced or exchanged.Your Caterpillar dealer can provide the parts that are needed to