Page 60 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

Removing the cylinder head
Learning objectives
1 List the four procedures in preparing an engine for disassembly.
2 Identify the differences in removing the cylinder heads from the L-head engine and the I-head or F-head
engine.
3 Identify the disassembly procedure for the rocker arm. The first engine component removed is the cylinder
head assembly, but before any disassembly is started, you must prepare the engine. A good repair or rebuild
job begins with engine preparation. Without good preparation, you may not only fail to locate unknown defects,
but you may also cause further damage.

Engine Preparation: With the engine removed from the vehicle, you can begin your preparation. The first
procedure is to cover all openings of the engine with clean, lint free rags. Look at figure 4-1. Note the arrows
indicating typical openings to be covered. Now imagine yourself as a surgeon and the engine as your patient. If
foreign matter enters your patient’s body, infection may result, and your operation could be a failure.
Engine Cleaning: Now that all openings are covered, the second procedure is to clean the engine thoroughly
to prevent foreign matter from entering the engine and causing internal damage during disassembly. First, take
a high-pressure cleaning unit and steam clean the entire outer surface of the engine. If a cleaning unit is not
available, use a high-pressure water hose to remove the dirt and loose matter. Next, with cleaning solvent and a
stiff brush, remove any grease or oil that may be on the engine. The third procedure is to drain the engine Using
two separate containers, one for oil and the other for the coolant, remove the oil pan drain plug and open the
cylinder block drain cock and drain the engine completely (fig 4-2). While the engine is draining, you might use
this time to make sure that your working area is thoroughly clean to prevent any chance of getting the internal
parts of the engine contaminated with dirt.

With the engine thoroughly cleaned and drained, the fourth procedure is to conduct a good visual inspection of
its outer surfaces for cracks and broken parts as you begin removing the accessories. If these conditions exist,
you must get a decision from a machinist on the feasibility of repairing the defects. New or rebuilt parts are of no
value if the engine block is damaged beyond repair.
At the point, you are ready to disassemble the engine. Mount the engine on the repair stand and begin the actual
disassembly. Remember to lay the parts out in an orderly manner as you disassemble the engine.
Doing so will make assembly easier.
Note: The removal and installation of the intake and exhaust manifold are not covered in this course. It is
essential, however, that these components be inspected and properly aligned for the engine to operate correctly.
As you disassemble the engine, check each part to make sure it can be used in the repair of the engine. If you wait
until reassembly, it will cause extra work and unnecessary time if you have to remove a part you earlier assumed
was good without checking. The three most common cylinder head engine types will be taught. Let’s begin with
the L-head engine.

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