Page 62 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

as the engine block was; therefore, it is unnecessary to go into a detailed description. Let’s get right to inspection
and the repair of the cylinder head.
Cylinder Head Inspection and Repair
Begin disassembly by removing the valves. With a valve spring compressing tool compress the valve spring and
remove the valve stem locks. There are various types of valve spring compressors.
The one described is one of the more common. The spring is compressed by placing the solid end of the
compressing tool on the valve head and the split end of the spring retainer, then compress it with the lever located
on the tool.
Once this is accomplished, you can easily remove the valve stem locks with your fingers. Cup your hand over the
end of the spring now and release the lever. The valve spring and its related parts are then removed by hand?
The valve may also be removed from the bottom side of the cylinder head by hand.
Keeping each valve and its related components together, lay them out on a clean surface and carefully inspect
each piece for damage.

Now, remove the coolant outlet connection and check the thermostat operation. To remove the outlet connection,
simply remove the cap screws retaining it and lift it from the head.
Remove the thermostat and drop it into boiling water to check its operation. The thermostat should open.
Remove the expansion plugs and replace them as you did in the engine block.
Check the head for nicks, burrs, and cracks. Smooth any nicks and burrs with oil stone. A cracked head may be
sealed in some cases. The cylinder head is now ready for specification checks.
The flatness check is performed to ensure that the head is not warped. This check is made in the same manner
as the cylinder head gasket surface of the cylinder block. A straight edge and a feeler gage are used to determine
the amount of warpage. Fig 5-25 is a good illustration of how to perform the checks.
Checking cylinder head flatness
Fig 5-26 shows where these checks should be made. The lines drawn across the surface indicate the positions
in which the straight edge should be placed for checking. If you were working on a cylinder head from an L-head
engine, this is the only check you would be required to make.

If the results of the check reveal that the cylinder head warpage exceeds the tolerances listed in the TM, you must
have the head ground to obtain a new, flat surface. In some cases, the head may have already been ground as
far as allowed and in other cases, heads are manufactured in such a design that they cannot be ground at all. In
these cases, discard the cylinder head and obtain a new one through the supply system.
Valve Seat Inspection and Repair

Your first step would be a visual inspection. It is important that the valve seat be of the proper width to ensure an
air-tight seal and proper valve cooling. Although the entire surface of the valve seat is machined smooth, only a
small portion of that surface is actually contacted by the valve when it is closed.

49
CITS : Automotive - Mechanic Diesel - Lesson 11 - 14 CITS : Automotive - Mechanic Diesel - Lesson 11 - 14