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Chapter 10

Chapter 10. Cylinder Block Inspection and Service. Objectives. Analyze wear and damage to cylinder block Select and perform most appropriate repairs to block. Objectives. R&R cam bearings, galley plugs, and core plugs Explain theories of cylinder wall surface finishes. Cleaning the Block.

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Chapter 10

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  1. Chapter 10 Cylinder Block Inspection and Service

  2. Objectives • Analyze wear and damage to cylinder block • Select and perform most appropriate repairs to block

  3. Objectives • R&R cam bearings, galley plugs, and core plugs • Explain theories of cylinder wall surface finishes

  4. Cleaning the Block • Disassemble • Remove all core plugs and oil gallery plugs • Remove cam bearings • Hot tank block and flush thoroughly to remove caustic solution and sediment

  5. Cleaning the Block • Lubricate all machined surfaces • Check block for cracks in cylinder bores and lifter valley

  6. Oil and Water Plugs • Must be cleaned after hot tanking to prevent loosened particles from entering engine after reassembly • Use a stiff bristle brush with hot soapy water

  7. Oil and Water Plugs • Three types of gallery plugs • Female plug • Male plug • Allen-type plug

  8. Oil Jet Cooling • Original intent of the jets on the inside of piston was to provide lubrication to wrist pins • Pistons are prone to increased heat, thus cooling this area is important • Be careful when removing jets to clean the oil galleries

  9. Aligning Dowels on the Back of the Block • Dowels align the transmission or transaxle housing to the engine • Aligning dowels should be in good condition to avoid misalignment • Sweet transmission pump area with dial indicator attached to the crankshaft if misalignment is suspected

  10. Main Bearing Caps and Registers • Fit in to machined slots in block • Bores are bored at factory with caps in place • Caps are not interchangeable

  11. Main Bearing Caps and Registers • Some engines use four or more bolts to support main cap • Some engines use a bedplate for extra strength

  12. Main Bearing Caps and Registers

  13. Main Bearing Bore Alignment • Repeated heating and cooling of an engine block • Can cause misalignment of main bearing caps • Check main bearing saddle bore alignment with feeler gauge and straight bar • Blocks can be remachined to correct misalignment

  14. Main Bearing Bore Alignment

  15. Checking Main Bearing Bore Alignment • Coat main journals of crankshaft with Prussian Blue • Install crank and bearings I block • After torquing main caps, rotate crankshaft twice

  16. Checking Main Bearing Bore Alignment • Turn engine upside down and rotate engine twice • Carefully unbolt main caps and remove crank • At least 75% of bearing area should be “blued” for acceptable alignment

  17. Decking the Block • Clean deck surface with a file or whetstone • Remove any nicks or burs that may give false readings • Use a straight edge and a feeler gauge to check block deck for flatness

  18. Decking the Block • If block shows warpage, block should be decked • Machine shop will use a grinder or milling machine to deck block

  19. Inspecting Cylinder Bores • Inspect cylinders for taper and out-of-round wear • Maximum wear is at 90º to wrist pin • Due to lack of lubrication at top of cylinder

  20. Inspecting Cylinder Bores • Top of cylinder is subject to high pressure of the piston rings against cylinder wall • When air-fuel mixture is ignited

  21. Measuring the Bore • Square ring just below ring ridge • Measure ring gap with feeler gauge • Compare this measurement to butt gap measurement taken at bottom of cylinder

  22. Measuring the Bore • To determine taper, divide difference between the two gaps by three

  23. Deglazing Cylinders with Engine in Car • Rotate crank to BDC • Put a length of hose on bottom of glaze breaker • This prevents it from damaging crankshaft

  24. Deglazing Cylinders with Engine in Car • Newspaper at bottom of bore will protect crank from oily grit • It is not necessary to stroke all the way to bottom of cylinder

  25. Clean the Block of Grit • Hand brush or use air drill • Ordinary cleaning solvent will not lift grit from pores of metal • Check cylinder walls and crankcase for cleanliness

  26. Clean the Block of Grit • Following cleaning • Grit can often be found in crankcase area just under cylinder bores

  27. Reboring Cylinders • Cylinders with excessive or unusual wear or rust should be rebored • Following boring • Cylinders are honed to fit new oversized pistons • Popular oversize • .020", .030", and .040"

  28. Reboring Cylinders • Small change in compression ratio will occur when boring

  29. Ultrasonic Thickness Testing • Used to check thickness of cylinder walls • Determines if enough material exists in block to safely bore cylinder • Considered a non-destructive tester

  30. Ultrasonic Thickness Testing • Can produce sound waves from 500 KHz and 100 MHz • Higher frequencies for thinner materials • Lower frequencies for thicker metals

  31. Honing Cylinders • Two stones and two aluminum guides on a rigid hone • Ensure guides are not too tight against cylinder walls • As honing of each cylinder is completed • Allow stones to run with very little pressure for several strokes

  32. Honing Cylinders • Stroke hone at speed necessary to generate a crosshatch of between 20º and 30º off horizontal surface of block

  33. Cylinder Surface Finish • One micro-inch is one millionth of an inch • Higher micro-inch number • Means rougher finish • Average finish recommended • 25 to 30 micro-inches

  34. Cylinder Sleeves • Cylinder sleeve can be used to fix a cracked, rusted, defective cylinder • Most sleeves come with a 1/8” or 3/32” wall thickness

  35. Cylinder Sleeves • To install sleeve • Bore block • Cool sleeve and heat block • Press in sleeve

  36. Final Block Preparation • Clean block with soap and hot water • Oil machined surfaces • Clean all bolt holes • If block has been decked • Bolt holes can be chamfered at top to remove burrs • Clean out galleries with rifle brush

  37. Oil Gallery Plug Installation • Coat threaded oil gallery plugs with sealer or Teflon tape and tighten into block • Install press fit core plugs with red loctite • Cross stake outside of core holes with cold chisel

  38. Oil Gallery Plug Installation

  39. Coolant Core Plug Installation • Clean core holes in block with emery cloth • Put sealer on outside of core plug and drive into block • Lip is just past chamfer when core plug is properly installed on block • Core plugs of same diameter can have different depths

  40. Coolant Core Plug Installation

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