3512C Engine Caterpillar

Maintenance Recommendations

Usage:

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 speed

Generally, 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 vibration

An 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

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 a load factor of approximately 60 percent.

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Table 1
Interval	Fuel Consumption ⁽¹⁾	Service Hours
Top End Overhaul	1,500,000 L (396,255 US gal)	9,000
Major Overhaul	3,000,000 L (792,510 US gal)	18,000

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^( 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.

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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.

Severe Operation

Severe operation is the use of an engine that exceeds current published standards for that engine. Caterpillar maintains standards for the following engine parameters:

Horsepower
Range of rpm
Fuel consumption
Fuel quality
Altitude
Maintenance intervals
Selection of oil
Selection of coolant
Environmental qualities
Installation

Refer to the standards for your engine or consult your Caterpillar dealer in order to determine if your engine is operating within the defined parameters.

Severe operation can accelerate component wear. Engines that are operating under severe conditions may need more frequent maintenance intervals for the following reasons:

Maximum reliability
Retention of full service life

Because of individual applications, it is not possible to identify all of the factors which can contribute to severe operation. Consult your Caterpillar dealer about the maintenance that is needed for your specific engine.

The following factors can contribute to severe operation: environment, improper operating procedures and improper maintenance practices.

Environmental Factors

Extreme Ambient Temperatures

Extended operation in environments that are extremely cold or hot can damage components. Valve components can be damaged by carbon buildup if the engine is frequently started and stopped in very cold temperatures. Extremely hot inlet air reduces the performance capabilities of the engine.

Note: See this Operation and Maintenance Manual, "Cold Weather Operation" topic (Operation Section), or see Supplement, SEBU5898, "Cold Weather Recommendations".

Cleanliness

Unless the equipment is cleaned regularly, extended operation in a dirty environment and in a dusty environment can damage components. Built up mud, dirt, and dust can encase components. This can make maintenance difficult. The buildup can contain corrosive chemicals. Corrosive chemicals and salt can damage some components.