Operation of a diesel engine cannot be separated from the operation of the equipment the engine is driving. Therefore, for purposes of our discussion, we will assume that you, as the operator, are fully aware of the complete system you are running. Each type of engine and installation has its special operating routine. A systematic procedure has already been established, based on these special requirements and on the experience of the engine operators with the particular installation. You must respect and follow this procedure. The following information is general and should be considered as incomplete in terms of operation of any specific plant. While an engine is operating, its performance is monitored and observed for two purposes: (1) to recognize early any unsatisfactory opera-tion or impending malfunctions so that immediate casualty control procedures can be started, and (2) to develop a comparative record over a period of time so that gradually deteriorating conditions can be detected. For the latter purpose, you must keep a complete log of all operating conditions. Observe and record the operating pressures and temperatures in the log at hourly intervals. Compare the entries over a period of time and note any deviations from normal conditions. An example of an engine operating record is provided in figure 11-2.

You must be alert to changing or unusual noises made by the operating machinery. Gradually changing sounds are difficult to detect, especially if you are inexperienced. Often an on-coming watch will detect a new sound that the present watch was not aware of.

When unusual operating conditions occur, load, lubrication, cooling, engine speed, or fuel supply problems are usually responsible, either directly or indirectly. You must be alert to changes in any of these areas. In the next sections, we will provide you with some general guidelines.

Load

The manner of applying a load to an engine and the regulation of the load will depend on the type of load and the design of the system. The procedures for loading an engine, or placing it on the line, are established by the EOSS.

Whenever you are starting a cold engine, allow ample time to build the load up gradually. NEVER fully load an engine before it has been warmed up. Gradual application of the load will prevent damage to the engine from such conditions as uneven rates of expansion and inadequate lubrication at low temperatures. (An exception to this rule is the use of emergency generators, set up for automatic mode, in which the engines must take on rated loads as soon as they are started.)

Never operate a diesel engine for prolonged periods with less than one-third of its rated load. Combustion at low load is incomplete, so partially burned fuel and lubricating oil may cause heavy carbon deposits which will foul the valve stems, injector tips, piston rings, and exhaust systems. In addition to these problems, prolonged operation at low-load conditions may cause the exhaust valves to stick and burn, dilute the lubricating oil, scuff the cylinder liners, in-crease fuel consumption, and cause excessive smoke when the load is increased. If you must operate an engine at less than 30 percent power for more than 30 minutes, you should increase the load to above 50 percent power at the first opportunity.

Diesel engines are designed to operate up to full-load conditions for prolonged periods. However, diesel engines should NEVER be operated at an overload except in an emergency. This includes both excessive torque and engine speed. Overload may be indicated by excessive firing pressures and exhaust temperatures. When conditions indicate an overload, reduce the load immediately.

Lubrication

We discussed the importance of lubrication in chapter 8 of this training manual. The performance of the lubrication system is one of the most important factors of engine operation you can monitor. Indicators continuously show oil temperature and pressure in key parts of the system. While the engine is operating, you should monitor the indicators and sight glasses on a regular basis. An alarm (horn or siren) will usually warn you of low pressure. If an alarm is not installed (as for example on an engine that is used in a small boat), you must continuously monitor the oil pressure and check the oil level. Under typical operating conditions, you should be able to estimate the rate at which the engine burns its lubricating oil and to predict when replenishment will be needed.

The condition and cleanliness of the lubricating oil is critical for long engine life. Therefore, you should clear the metal-edge type of lubricating oil strainers by rotating the cleaning handle. (This procedure should be performed during each watch.) The condition of filters is often indicated by the amount of pressure drop from the inlet to the outlet. Gauges are installed to indicate this differential. You should check these gauges frequently. As mentioned in chapter 8, and as specified by PMS, a test kit is available for you to use to check the condition of the lubricating oil.

Figure 11-2.-Diesel engine operating record.