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Chapter 7

Chapter 7. Cylinder Head: Parts and Service. Objectives. Disassemble, clean, and inspect cylinder heads Analyze wear and damage to cylinder head parts Understand theory related to cylinder head parts Select and perform correct repair. Head Disassembly. Clean before disassembly

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Chapter 7

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  1. Chapter 7 Cylinder Head: Parts and Service

  2. Objectives • Disassemble, clean, and inspect cylinder heads • Analyze wear and damage to cylinder head parts • Understand theory related to cylinder head parts • Select and perform correct repair

  3. Head Disassembly • Clean before disassembly • Steam cleaned or hot tanked • If OHC, remove camshaft • Remove all rocker arms

  4. Spring Removal Tools • Wear face protection when removing valve springs • Come in manually operated and air-operated • Some are designed to work with heads still on engine

  5. Spring Removal Tools

  6. Head Disassembly • Keep valves in order • Keep valve components in storage container to prevent loss • Remove any o-ring seals • Valve tips • Dress with a file to remove mushrooming before removal

  7. Head Disassembly

  8. Measuring Stem Height • Distance between spring seat and valve spring retainer • Measure before any work is done • Vernier caliper or depth micrometer can be used

  9. Measuring Stem Height

  10. Removing Carbon from Combustion Chambers • Glass bead blast • Works well on cast iron and aluminum heads • Wire wheel with electric or air drill • Good on cast iron • Cannot be done on aluminum heads • Chemical carbon removers • Can be used on both iron and aluminum

  11. Removing Carbon from Valves • Glass bead blasting or wire wheel buffer • Clean valve keeper groove • Do not clean guide rub area of the valve

  12. Removing Carbon from Valves

  13. Crack Inspection • Cracks form in and between combustion chambers • Different methods to locate crack depending on style of head • Magnetic inspection • Dye penetrant • Pressure testing

  14. Crack Inspection

  15. Crack Repair • Only practical of bare head costs more than twice the repair • Cracks can be repaired in both iron and aluminum heads • Tapered plugs are installed into threaded holes drilled along crack • Welding is a common fix for aluminum heads • Occasionally done to cast iron

  16. Valve Guide Inspection • Worn valve guides are common cause of excessive oil consumption • Most wear occurs at bottom of guide due to heat and lack of lubrication • Clean guide before measuring • Measure with a ball gauge and outside micrometer

  17. Valve Guide Knurling • Repair process that does not require replacement of guide • Process that displaces metal in the guide • Ream guide to proper size after knurling process • Use lubrication when knurling cast iron guides, but NOT when reaming the guide.

  18. Valve Guide Repair

  19. Valve Guide Replacement • Come in either bronze or iron • Reamer used to cut the guide oversived • Guide is the pressed in • Top of guide cut off to proper height • Inside of guide is then reamed to proper clearance

  20. Valve Stem Seals • Umbrella seal • O-ring • Positive seal

  21. Valve Stem Seals

  22. Umbrella Seal Identification • Polyacrylate seals • Black • Nitrile seals • Blue or green

  23. Umbrella Seal Identification • Silicone seals • Red • Teflon seals • White

  24. Replacing Valve Springs or Seals (Head on Engine) • Induce air into cylinder • Loose both rocker arms • Compress and remove valve spring with special compressor • Check condition of valve guide by wiggling valve stem • Replace spring or seal

  25. Checking Cylinder Head Flatness • Heads with excessive warpage • Resurface to ensure proper gasket sealing • To check • Clean gasket surface • Use straight edge and feeler gauge • Check diagonally, vertically, and horizontally

  26. Resurfacing Heads • Cylinder head can be resurfaced by • Fly cutting on milling machine • Grinding on a head grinder • Sanding head on a belt sander machine

  27. Resurfacing Heads

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