Page 66 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Check the TM for the proper torque specifications and sequence. Figure 6-8 gives examples of cylinder heads
having two and three rows of head bolts. Note the tightening sequence for both.
The installation of the cylinder head on the I-head and F-head engines is the same as that for the L-head up to
this point. However, before head installation is considered complete on these two engines, the rocker arms and
pushrods must also be installed.
The pushrods are inserted through holes provided in the cylinder head. The bottom end of the pushrod must seat
in the recess located in the tip of the valve tappet or the engine will not operate and the pushrod will be damaged.
Engine Diagnosis and Service: Cylinder Head and Valve train
Disassemble a cylinder head in the correct manner Clean and inspect a cylinder head for cracks and warpage
Diagnose cylinder head and valve train wear problems and determine the correct repair procedure Understand
machine shop repair processes for cylinder heads.
Objectives (cont’d.)

• Reassemble a cylinder head
• Understand camshaft and cam drive service procedures Introduction
• Valve job
• Cylinder head is removed for valve refinishing

• Leaking head gasket
• Removed for resurfacing and gasket replacement
• Timing chain or timing belt service
• Important maintenance procedures on today’s long-life engines
Head Disassembly and Carbon Removal

• Cylinder heads: easier to work on if clean
• OHC heads with removable cam caps: verify caps are correctly numbered
• Removing valve springs: wear face protection
• Keep valves in order

• Measure and record valve stem and spring height
• Carbon removal
• Most OHC heads have oil galleries
• Carbon can be removed from necks of valves
Cylinder Head Inspection
Cylinder heads sometimes warp

• Warped heads are resurfaced
• Clean head before checking for flatness
• Rock the straightedge so one edge of it rests against the opposite side of the head
• A round, straight bar is also available for checking straightness

• Warpage
• Cast iron head warpage
• Aluminum head warpage
Resurfacing by Grinding, Cutting, or Sanding
• Resurfacing methods

• Fly-cutting

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CITS : Automotive - Mechanic Diesel - Lesson 11 - 14 CITS : Automotive - Mechanic Diesel - Lesson 11 - 14