Page 61 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

L-head Engine: You have already inspected the outer surfaces of the cylinder head along with the rest of the
engine. The internal portion of the head must be cleaned before it can be inspected. When you remove the
cylinder head, lay it aside and inspect it later in a separate area. To clean it now would result in carbon deposits
flying through the air, possibly contaminating the rest of the engine.
The removal of the cylinder head from an L-head engine is very simple. Remove the cylinder head bolts from the
head, lift the cylinder head from the engine, and lay it flat on a flat surface. To stand it on end or lean it against
another object would result in the head warping which in many cases could require repairs that would not have
been necessary. At this time, also remove the cylinder head gasket, inspect it for signs of leakage, and discard
it. Any signs of leakage should be recorded so that you may concentrate on the cause during your cylinder head
and cylinder block gasket surface inspection.
I- or F-head Engine: Removing an I- or F-head engine’s cylinder head requires a little more effort. First, remove
the rocker arm cover and discard the gasket and retaining seals. At this time, check the retainer seal surface of
the cover for dents. Check for any other dents. Some mechanics have a tendency to over-torque the retaining
nuts and bolts; this bends the retainer seal surface of the cover. If a dent exists, you may straighten it at this time
or record the defect so that it is not forgotten.
With the cover removed, back off (loosen) the valve adjustment at least one complete turn to relieve the pressure
on the rocker arms (fig 4-3). If the pressure is not relieved, damage to the rocker arm shaft could result when it
is being removed.

Relieving rocker arm pressure
When the pressure is relieved, remove the rocker arm attaching bolts and nuts and lift the rocker arm shaft from
the engine. If the engine does not have a rocker arm shaft, simply remove the rocker arm.
Once the shaft is removed, you might make a preliminary inspection by removing a couple of rocker arms and
checking their pivot points on the shaft. If you find grooves worn into the shaft, discard both the shaft and the
rocker arms, retaining all other parts.
To prevent damage to the pushrods when the cylinder head is removed, take them out of their holes (before
removing the cylinder head) and lay them in order on your workbench or in the area you are storing the parts you
have removed. You might as well take this opportunity to ensure that all the pushrods are perfectly straight. A
bent rod will continue to bend when reinstalled in the engine. Discard any bent rods and make a note of the holes
from which they were removed. Now, loosen the cylinder head bolts, lift the head from the engine, and lay it on
a flat surface.
Cylinder head
The cylinder head from an L-head engine does not require major disassembly. Therefore, the disassembly portion
of this study unit refers mostly to the I-head and F-head engines. The cylinder head is cleaned and inspected just

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CITS : Automotive - Mechanic Diesel - Lesson 11 - 14