0391630 JOHNSON CAP ASSEMBLY

Using Fuel Consumption For Calculating the Overhaul Intervals
Experience has shown that maintenance intervals are most accurately based on fuel consumption. Fuel consumption corresponds more accurately to the engine load. Table 1 lists average ranges of fuel consumption and service hours for 3512Bengines. These tables are based on a load factor of approximately 60 percent.
Table 1
Service Hours and Fuel Consumption for 3512B Engines (1)    
Interval     Rated Up To 1300 RPM     Rated 1301 to 1600 RPM     Rated 1601 to 1800 RPM    
250 Service Hours    
33400 L (8800 US gal)    
41000 L (10800 US gal) of fuel    
48500 L (12800 US gal) of fuel    
500 Service Hours    
66800 L (17600 US gal)    
82000 L (21600 US gal) of fuel    
97000 L (25600 US gal) of fuel    
1000 Service Hours    
133500 L (35000 US gal)    
164000 L (43200 US gal) of fuel    
194000 L (51200 US gal) of fuel    
2000 Service Hours    
267000 L (70000 US gal)    
328000 L (86400 US gal) of fuel    
388000 L (102400 US gal) of fuel    
3000 Service Hours    
398000 L (105000 US gal)    
491000 L (129600 US gal) of fuel    
582000 L (153600 US gal) of fuel    
6000 Service Hours    
796000 L (210000 US gal)    
982000 L (259200 US gal) of fuel    
1164000 L (307200 US gal) of fuel    
Top End Overhaul     11000 Service Hours     9000 Service Hours     7500 Service Hours    
1500000 L (395000 US gal) of fuel
Second Top End Overhaul     22000 Service Hours     18000 Service Hours     15000 Service Hours    
3000000 L (790000 US gal) of fuel
Major Overhaul     33000 Service Hours     27000 Service Hours     22500 Service Hours    
4500000 L (1185000 US gal) of fuel
( 1 ) Fuel consumption is based on a load factor of approximately 60 percent.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 fuel consumption data in the Technical Marketing Information (TMI) for your engine. This will determine the fuel consumption for the percent of the load that was estimated in Step 1. Use this figure as variable "F" for the equation in Table 2. For more information about the Technical Marketing Information (TMI) for your engine, consult your Caterpillar dealer.
Table 2
Equation For Calculating Overhaul Intervals    
F/R = H    
"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.    
"H" is the number of estimated hours until the overhaul interval.    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.