Figure 3-45.—A typical P-250 pump unit.For more detailed information concerningoperation, maintenance and repair of the P-250, refer tothe NAVSEA technical manual, Firefighter PumpP-250 Mod 1, S6225-BW-MM0-010.Some gasoline engines serve as outboard motors topower small boats. A high percentage of the motors’problems are electrical. A large number of problems arealso caused by the use of fuel with a lower octane contentthan specified by the manufacturer. To gain knowledgeabout operating, maintaining, and repairing outboardmotors, review manufacturers’ service manuals andassigned PMS publications. Most outboard motormanufacturers offer a high quality training course, freeof charge.JACKING GEARThe Engineman 3, NAVEDTRA 10539, introducedthe two primary types of jacking gear, the ring gear, andthe pinion assembly, and described their use. The onlymaintenance required for jacking gear is periodicinspection for wear and minor lubrication of the movingparts of the pinion assembly.FUEL AND OIL PURIFIERSSpecific directions for operating a purifier are givenin the manufacturer’s instructions provided with theunit. The following information is general and appliesto both the fuel and the oil purifiers.For maximum efficiency, purifiers should beoperated at their maximum designed speed and ratedcapacity. An exception to operating a purifier at itsdesigned rated capacity is when the unit is used as aseparator with 9000 series detergent oil. Some enginesusing the 9000 series oils are exposed to large quantitiesof water. When the oil becomes contaminated withwater, it has a tendency to emulsify. The tendency toemulsify is most pronounced when the oil is new andgradually decreases during the first 50 to 75 hours ofengine operation. During this period, the purifiercapacity should be reduced to approximately 80 percentof its rated capacity.Most oils used in Navy installations can be heatedto 180°F without damage to the oils. Prolonged heatingat higher temperatures is not recommended becausesuch oils tend to oxidize at high temperatures. Oxidationresults in rapid deterioration. In general, oil should beheated enough to produce a viscosity of approximately90 seconds Saybolt universal (90 SSU), but thetemperature should not exceed 180°F. The followingtemperatures are recommended for purifying oils in the9000 series:3-46
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