Cylinder Head: Parts and Service 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 If OHC, remove camshaft Steam cleaned or hot tanked If OHC, remove camshaft Remove all rocker arms

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

Spring Removal Tools

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

Head Disassembly

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

Measuring Stem Height

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

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

Removing Carbon from Valves

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

Crack Inspection

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

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

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.

Valve Guide Repair

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

Valve Stem Seals Umbrella seal O-ring Positive seal

Valve Stem Seals

Umbrella Seal Identification Polyacrylate seals Black Nitrile seals Blue or green

Umbrella Seal Identification Silicone seals Red Teflon seals White

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

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

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

Resurfacing Heads