Maintenance of internal combustion engine parts


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Maintenance of internal combustion engine parts

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Maintenance of internal combustion engine parts

  1. 1. After studying this exercise, students will be able to understand: i. the inspection methods of various parts of I.C. engines, ii. the repair procedure of various parts of I.C. engines. f ! " Preventive maintenance ensures that an internal combustion (I.C.) engine will operate efficiently. By following the schedule, engine casualties are reduced and engine achieves its normal number of operating hours between overhaul periods. While performing Whi an engine maintenance or overhaul, some precautions have to be taken such as: planning the work, before beginning a repair keep necessary tools/parts ready, keeping the necessary forms ready to record the clearances, dimensions, and measurements and measureme checking precision measuring instruments before using them. Apart from this keeping the work area clean, not allowing oil to accumulate on the deck or accumula on the tools, Before starting to inspect/repair, clean the outside of the engine thoroughly. This will help you spot cracks, leaks, and other problems more easily than if the engine is dirty. " Engine block is made of grey cast iron. It is single piece casting consisting of cylinders, water jacket, passageways, openings for inlet and outlet valves etc. Engine block inspections: Inspect the top surface of the cylinder block for damage (warpage). You can use a straightedge, a feeler gauge, and a good light. Figure 4(a) illustrates how to use a straightedge and a feeler gauge to check the top surface of the cylinder block. Visually inspect the cylinder block for cracks, breaks, or other damage. Measure the bore in the cylinder block, with a dial indicating bore gauge, to determine if wear or an outdetermine out of-round condition exceeds the manufacturer’s specification. Figure 4(b) illustrates the use of a bore gauge to measure a cylinder bore. An inside micrometer can be used as well, but a dial indicating bore gauge is easier to use. ! ! "
  2. 2. Tests: A dye penetrant test should be conducted on the engine block’s surface to identify cracks that are not identified by visual inspection. # $ ! " Cylinders are provided with liners which may be of wet and dry type depending on whether water comes into direct contact with liner or not. Cylinder liners have to be inspected if any of the following problems have encountered: Excessive water in the lubricating oil, Oil in the cooling water etc. Reasons for cracking, distorting of cylinder liners: poor cooling which causes hot spots on liners, Scale formation due to improper cooling foreign bodies in the combustion space, or erosion and corrosion etc. Visual inspection and tests: Use testing method, such as the water pressure test or air pressure test i.e. passing pressurised air or water through liners. To check liners for leaks, fill it with glycol-type antifreeze. This liquid will leak from even the smallest cracks. Use of magnaflux equipment or penetrating dye to locate these cracks is also possible. $ ! " Cylinder Head is mounted on the cylinder block and valves, spark plug etc. are fitted in it. The cylinder head is held tight to the cylinder block by number of bolts or studs. Common problems in and on cylinder head are: Cracks, Distortion and Warpage. Cracks in cylinder heads are located by either visual inspection or dye penetrant test. Distortion may be caused by improper welding of cracks or by improper tightening of the cylinder head studs. Repair of distorted or damaged cylinder heads is impossible. They should be replaced as soon as possible. Procedure for cleaning cylinder head: 1. Immerse the cylinder head into a dip or soak type of cleaning tank and allow it to soak until all baked grease, oil and paint have been removed. Two hours are sufficient for this purpose. 2. Remove the cylinder head from cleaning tank and steam clean or rinse with hot water. 3. Blow out all the passageways with compressed air. 4. Place the head on some type of suitable stand or bench and san the cylinder head gasket surface with a sander. ! " # ! ! "
  3. 3. $ % & # ' ( # ) * % & # ! " Piston: It receives the energy from the combustion of fuel and transmits it to the crankshaft. The piston must withstand heavy stress under severe temperature extremes. It is a cylindrical component fitted into the cylinder forming the moving boundary of the combustion system. It fits perfectly into the cylinder providing a gas-tight space with the piston rings and the lubricant. Piston wear is affected by lubrication. An adequate supply of oil is essential to provide the film necessary to cushion the piston and other parts within the cylinder and prevent metal-to-metal contact. Inadequate lubrication will cause piston seizure, and piston pin busing wear. The pressure-recording instruments usually give warning of low oil pressure before any great harm results. Piston faces troubles due to improper cooling water temperature. If an engine is not operated within the specified temperature limits, lubrication troubles will develop. High cylinder surface temperatures will reduce the viscosity of the oil. As the cylinder lubricant thins, it will run off the surfaces. The resulting lack of lubrication leads to excessive piston and liner wear. ' ! " There are certain unavoidable troubles, such as cracked connecting rods caused by defective material. Such cracks must be discovered before they develop to a point that the rod fails. Magnaflux testing is considered the best method for locating cracks. If you discover a crack in a connecting rod, replace the rod; do not try to repair it. If you have to replace a damaged rod, send it, with other damaged parts, to a salvage center for possible reclamation. Do not repair defective connecting rod bolts, except for removing ! ! "
  4. 4. small burrs by using a fine rectangular file. If you doubt the condition of a bolt or a nut, replace it. Check the connecting rod bore for out-of-roundness with an inside micrometer. Make the correction and recheck the bore. If the distortion is permanent, replace the rod. You can make plugged oil passages of connecting rods serviceable by running a wire through them. In extreme cases, you may need to drill the passages free of foreign matter. Procedure for inspection of connecting rods: 1. Measure the rod end bore out of roundness with the help of snap gauge. 2. Rod big bore end should be measured with the help of snap gauge and inside micrometer in same manner like small end. If big end does not meet specifications it should be reconditioned and replaced. 3. If it meets the specifications, it should be checked for straightness. 4. If rod is not straight, it should be replaced or reconditioned. + , (1) . " # (2) (3) ! (4) . (5) # / " 0 % (1) . (2) 1 (3) # /# 5 (5) " 5 (4) " 2 3 6 2 " 4 & " * " " # * 7 % 8 " (1) 9: 3 (2) 6 " " " ; # " " # ; ! ! "
  5. 5. (3) 3# (4) = (5) & < 3 # " ; ; & ; , # # 1 # # 2 # # # $ '/ # )( # # # # " # # +> 2 # Date and Signature of Faculty: ________________ ! ! "