1. Cylinder Head: Parts and Service
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 If OHC, remove camshaft
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