Shibaura SG280E, Workshop Manual

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13
1) During an overhaul
Wear in cylinders, pistons, rings, and valves lead directly to the need for an engine overhaul. External indications of
such wear take a variety of forms, making it difficult to make a certain judgment. Therefore, the best method is to
perform inspections and maintenance on a regular basis, record the results, and then make a judgment based on that
data.
External indications of wear and/or damage to cylinders and pistons often include the following, in various combinations:
Reduced compression pressure
Increased consumption of engine oil
Increased consumption of fuel
Poor start up
Reduced output
Increased engine noise
Increased blow-by of explosive gas into the cylinder block, and increased gas from the air breather
Primary indicators for the need of an overhaul include the following:
1. Reduced functioning of battery and starting motor
2. Wear on cylinders, pistons, and piston rings
3. No valve clearance
4. Reduced functioning of injection pump
5. Defective nozzle and valve during injection
2) General precautions during an overhaul
When disassembling the engine, use an engine stand and a work stand for the disassembled parts, and arrange the
parts in order according to the disassembly procedure.
When disassembling the engine, pay careful attention to the assembly marks so that the engine can be assembled
back the way it was. If some parts do not have assembly marks, add marks as necessary.
When disassembling and/or washing the engine, always be careful to check for defects that would not be noticed
after disassembly and/or washing is complete.
During disassembly and assembly, use the correct tools to avoid damaging parts. In addition, be sure to lubricate
movable parts, and use a torque wrench to tighten parts that have a specific tightening torque.
Replace gaskets and packing. Use fluid packing when necessary to prevent leaks.
Use appropriate tools to tighten bolts and nuts to an appropriate torque, unless specified otherwise.
2-3 General precautions for disassembly/
assembly