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Cylinder Head Disassembly & Repair Guide

Learn how to disassemble, clean, and inspect cylinder heads, analyze wear, select repair methods, and inspect cracks. Understand valve guide repair and replacement procedures for proper engine maintenance.

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Cylinder Head Disassembly & Repair Guide

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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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