922522-6410 Nissan SCREW

Table 1
Major Overhaul
Service Hours and Fuel Consumption for 3512B Marine Auxiliary Engines (1)
Rated 1601 To 1800 RPM
15 000 Service Hours
2 920 000 L (770,000 US gal) of fuel
(1) Fuel consumption is based on a load factor of approximately 60 percent.The need for a major overhaul is determined by several factors.
An increase of oil consumption
An increase of crankcase blowby
The total amount of fuel consumption
The service hours of the engine
The wear metal analysis of the lube oil
An increase in the levels of noise and vibrationAn 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.A major overhaul includes all of the work that is done for the top end overhaul and the general inspection. A major overhaul includes additional parts and labor. Additional parts and labor are required in order to completely rebuild the engine.For the major overhaul, all of the bearings, seals, gaskets, and components that wear are disassembled. The parts are cleaned and inspected. If necessary, the parts are replaced. The crankshaft is measured for wear. The crankshaft may require regrinding. Alternatively, the crankshaft may be replaced with a Caterpillar replacement part.Your Caterpillar dealer can provide these services and components. Your Caterpillar dealer can ensure that the components are operating within the appropriate specifications.If you elect to perform an overhaul without the services of a Caterpillar dealer, be aware of the following recommendations.Replacement of Components
During the major overhaul, replace the components that are listed in Table 2.
Table 2
Components For Replacement During A Major Overhaul
Connecting rod bearings
Crankshaft seals
Crankshaft vibration damper
Electronic unit injectors
Engine wiring harness
Main bearings
Piston rings Inspection, Reconditioning or Exchanging of Components
Inspect the components that are listed in Table 3 according to the instructions that are in Caterpillar reusability publications. Refer to Guidelines for Reusable Parts and Salvage Operations, SEBF8029, "Index of Publications on Reusability or Salvage of Used Parts".Recondition the worn components or exchange the components, if necessary. Your Caterpillar dealer can provide these services and components.
Table 3
Components For Inspection, Reconditioning, Or Replacement During A Major Overhaul
Camshaft followers
Connecting rods
Cylinder head assembly
Cylinder liners
Exhaust bellows
Fuel transfer pump
Oil pump
Pistons
Piston pins
Prelube pump
Spacer plate
Turbochargers Inspection of Components
Inspect the components that are listed in Table 4 according to the instructions that are in Caterpillar reusability publications. Refer to Guidelines for Reusable Parts and Salvage Operations, SEBF8029, "Index of Publications on Reusability or Salvage of Used Parts".
Table 4
Components For Inspection During A Major Overhaul
Camshaft
Camshaft bearings
Crankshaft
Crankshaft thrust washers
Driven equipment (alignment)
Electronic control module
Front gear train
Gear train bushings and bearings
Rear gear train Inspect the camshaft for damage to the journals and the lobes. Inspect the following components for signs of wear and/or for signs of fatigue:
camshaft bearings
camshaft followersInspect the crankshaft for any of the following conditions:
deflection
damage to the journals
bearing material that has seized to the journalsCheck the journal taper and the profile of the crankshaft journals. Check these components by interpreting the wear patterns on the following components:
rod bearing
main bearingsNote: If the crankshaft or the camshaft are removed for any reason, use the magnetic particle inspection process to check for cracks.Replace the crankshaft vibration damper if any of the following conditions occur:
Engine failure due to a broken crankshaft
Excessive wear of the front bearing for the crankshaft
Excessive wear of the gear train that is not caused by a lack of lubricationInspect the gears of the gear train and inspect the gear train bushings for the following conditions:
Worn gear teeth
Unusual fit
Unusual wearIn addition to the inspection of components, inspect the alignment of the driven equipment. See the Application and Installation Guide for the engine or see the literature that is provided by the OEM of the driven equipment.Cleaning of Components
Clean the components that are listed in Table 5. For instructions on removal and installation of components, see the Service Manual, "Disassembly and Assembly" module.
Table 5
Components For Cleaning During A Major Overhaul
Aftercooler core (1)
Oil cooler core (1)
Oil suction screen
Oil sump
(1) After the core has been cleaned, pressure test the core.Obtain a Coolant Analysis
Obtain a coolant analysis during a major overhaul. Caterpillar recommends an S O S coolant analysis (Level II). This is a comprehensive chemical evaluation of the coolant. This analysis is also a check of the overall condition of the inside of the cooling system. The following services are provided:
Full Level I analysis
Identification of the source of metal corrosion and of contaminants
Identification of buildup of the impurities that cause corrosion
Identification of buildup of the impurities that cause scaling
Determination of poss