9011G43 Mercury GEAR HOUSING ASSEMBLY-COMPLETE

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 service life 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 serviced. An increase in the levels of noise and vibration indicates that rotating parts require service.Note: Oil analysis may 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 Cat 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
Experience has shown that maintenance intervals are most accurately based on fuel consumption. Fuel consumption corresponds more accurately to the engine load. Table 1 list average ranges of fuel consumption and service hours for a load factor of approximately 40 percent. Table 2 list average ranges of fuel consumption and service hours for a load factor of approximately 25 percent.
Table 1
Maintenance Interval Schedule
Service Hours and Fuel Consumption for 3512C Locomotive Engines (1)    
Interval     Rated 1601 To 1800 RPM    
Top End Overhaul     10000 Service Hours    
1500000 L (396300 US gal)
In-Frame Inspection/Overhaul     20000 Service Hours    
3000000 L (792600 US gal)
Second Top End Overhaul     30000 Service Hours    
4500000 L (1188900 US gal)
Major Overhaul     40000 Service Hours    
6000000 L (1585200 US gal)
( 1 ) Fuel consumption is based on a load factor of approximately 40 percent.
Table 2
Maintenance Interval Schedule
Service Hours and Fuel Consumption for 3512C Locomotive Engines (1)    
Interval     Rated 1601 To 1800 RPM    
Top End Overhaul     18000 Service Hours    
1500000 L (396300 US gal)
In-Frame Inspection/Overhaul     36000 Service Hours    
3000000 L (792600 US gal)
Second Top End Overhaul     54000 Service Hours    
4500000 L (1188900 US gal)
Major Overhaul     72000 Service Hours    
6000000 L (1585200 US gal)
( 1 ) Fuel consumption is based on a load factor of approximately 25 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 data 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 3. For more information about the Technical Marketing Information (TMI) for your engine, consult your Cat dealer.
Table 3
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 Cat 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 Cat dealer for assistance in determining the typical oil consumption rate for your engine.When engine 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.