Low oil level in hydraulic governors may be causedby oil leaking from the governor or failure to maintainthe proper oil level. Leakage of oil from a governor cangenerally be traced to a faulty oil seal on the drive shaftor power piston rod, or to a poor gasket seal betweenparts of the governor case.Check the condition of the oil seals if oil must beadded too frequently to governors with independent oilsupplies. Oil seal leakage may or may not be visible onexternal surfaces. There will be no external sign ifleakage occurs through the seal around the drive shaft,while leakage through the seal around the power pistonwill be visible.Oil seals must be kept clean and pliable. Store themproperly so they do not become dirty or dry and brittle.Leaky oil seals cannot be repaired. They must bereplaced. You can prevent some leakage troubles simplyby following proper installation and storage instructionsfor the seals.Most manufacturer’s technical manuals supplyinformation on the governor. Special hydraulic governormaintenance manuals made available by the Naval SeaSystems Command are the Marquette GovernorManual, NAVSHIPS 341-5505 (0341-LP-550-5000),and theWoodward Governor Manual, NAVSHIPS341-5017 (0341-LP-501-7000).Inoperative Overspeed Safety DevicesOverspeed safety devices are designed to shut offfuel or air in case of excessive engine speed. Thesedevices must be maintained in operable condition at alltimes. Inoperative overspeed devices may also cause anengine not to start. They may be inoperative because ofimproper adjustment, faulty linkage, or a broken spring,or the overspeed device may have been accidentallytripped during the attempt to start the engine.If the overspeed device fails to operate when theengine overspeeds, the engine may be secured bymanually cutting off the fuel oil or the air supply to theengine. Most engines have special devices or valves tocut off the air or fuel in an emergency.Insufficient Cranking SpeedIf the engine cranks slowly, the necessarycompression temperature cannot be reached. Lowstarting air pressure may be the cause of such trouble.Slow cranking speed may also be the result of anincrease in the viscosity of the lubricating oil. Thistrouble occurs during periods when the air temperatureis lower than usual. The oil specified for use duringnormal operation and temperature is not generallysuitable for cold climate operation.IRREGULAR ENGINE OPERATIONAs the engine operator, you must constantly be alertto detect any symptoms that might indicate trouble. Suchsymptoms may be sudden or abnormal changes in thesupply, temperature, or pressure of the lubricating oil orcooling water. Color and temperature of the exhaust mayalso indicate abnormal conditions. Check themfrequently. Fuel, oil, and water leaks indicate possibletroubles. Keep the engine clean to make such leakseasier to spot.You will soon become accustomed to the normalsounds and vibrations of a properly operating engine. Ifyou are alert, an abnormal or unexpected change in thepitch or tone of an engine’s noise or a change in themagnitude or frequency of a vibration will warn you thatall is not well. A new sound such as a knock a drop inthe fuel injection pressure, or a misfiring cylinder areother trouble warnings for which you should beconstantly alert during engine operation.The following discussion on possible troubles, theircauses, and the corrective action necessary is generalrather than specific. The information is based oninstructions for some of the engines used by the Navyand is typical of most. A few troubles listed may applyto only one model. For specific information on anyparticular engine, consult the manufacturer’s technicalmanual.ENGINE STALLS FREQUENTLY OR STOPSSUDDENLYWe discussed earlier several of the troubles that maycause an engine to stall or stop. Such troubles as air inthe fuel system, clogged fuel filters, unsatisfactoryoperation of fuel injection equipment, and incorrectgovernor action not only cause starting failures orstalling but also cause other troubles as well. Forexample, clogged fuel oil filters and strainers may leadto a loss of power, to misfires or erratic firing, or to lowfuel oil pressure. Unfortunately, a single engine troubledoes not always manifest itself as a single difficulty butmay be the cause of several major difficulties.Factors that may cause an engine to stall includemisfiring, low cooling water temperature, improperapplication of load, improper timing, obstruction in thecombustion space or in the exhaust system, insufficient3-30
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