86978A 1 Mercruiser DRIVE SHAFT 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.
Overhaul intervals are guidelines and depend on the maintenance and usage factors described in this Operation and Maintenance Manual.
Maintenance intervals must be reduced for engines that operate in a severe service application. Maintenance intervals must be reduced for engines that operate beyond the engine rating.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 the oil consumption of an engine has risen to three times the original oil consumption rate, 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
InstallationRefer to the standards for your engine or consult your Cat dealer 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 lifeBecause of individual applications, all the factors which can contribute to severe operation cannot be identified. Consult your Cat 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 too cold or too hot can damage components. Valve components can be damaged by carbon buildup if the engine is frequently started and stopped in temperatures that are too cold. Inlet air that is too hot reduces the performance capabilities of the engine.Note: See this Operation and Maintenance Manual, "Cold-Weather Operation" topic (Operation Section), or see Special Publication, 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 and make maintenance difficult. The buildup can contain corrosive chemicals. Corrosive chemicals and salt can damage some components.Improper Operating Procedures
Extended operation at low idle
Minimum cool down periods after high load factor operation
Operating the engine beyond the guidelines for the engine rating
Operating the engine at loads that are greater than the rated load
Operating the engine at speeds that are greater than the rated speed
Use of the engine for an application that is not approvedImproper Maintenance Practices
Extension of maintenance intervals
Not using recommended fuel, lubricants, and coolant