1.2 Cylinder Head
DETROIT DIESEL 53
2. Check the bottom (fire deck) of the cylinder head for
flatness as follows:
a. Use an accurate straightedge and feeler gage
J 3172 to check for transverse warpage at each
end and between all of the cylinders. Also,
check for longitudinal warpage in six places as
shown in Fig. 3.Maximum allowable warpage is
given in the following chart:
Maximum
Maximum
Engine
Longitudinal
Transverse
Warpage
Warpage
6V-53
.005"
.040"
b. The maximum allowable warpage limits should
be used as a guide in determining the
advisability of reinstalling the head on the
engine or of refacing it. The number of times a
cylinder head may be refaced will, of course,
Fig. 3. - Checking Bottom Face of Cylinder
depend upon the amount of stock removed from
Head for Warpage
the head during previous reworking operations.
b. Install dummy or scrap injectors to ensure seating of
c.
If the cylinder head is to be refaced, remove the
the injector tubes. Dummy injectors may be made
injector tubes prior to machining. Not over .020"
from old injector nuts and bodies - the injector spray
of metal should be removed from the fire deck
tips are not necessary. Tighten the injector clamp
of the cylinder head. The distance from the top
bolts to 20-25 Ib-ft torque.
to the bottom (fire deck) of the cylinder head
must not be less than 4376", as shown in (Fig.
c.
Drill and tap into one of the water hole cover plates
4).
for an air hose connection and apply 80- 100 psi air
Stamp the amount of stock removed on the face of the
pressure to the water jacket. Then, immerse the
fire deck near the outer edge of the head, in an
head in a tank of water previously heated to 180-
area not used as a sealing surface.
200F. for twenty minutes to thoroughly heat the
cylinder head. Observe the water in the tank for
d. After a cylinder head has been refaced and new
bubbles indicating cracks or leaks.
injector tubes have been installed as outlined in
Section 2.1.4, pressure check the cylinder head
d. Remove the cylinder head from the tank and dry it
as outlined in Step 1.
with compressed air.
3. Inspect the cam follower bores in the cylinder head
for scoring or wear. Light score marks may be cleaned
e. If inspection revealed cracks, replace the cylinder
head.
f.
Replace any leaking injector tubes as outlined in
Section 2.1.4.
Over a prolonged period of operation, the cylinder head
may assume a contour to match that of the cylinder
block, which is normal. However, if the cylinder head is
Fig. 4. - Minimum Distance Between Top and
allowed to become overheated because of coolant loss,
Bottom Faces of Cylinder Head
the resultant high temperatures cause stresses to occur
in the casting which will affect the flatness of the head.
1970 General Motors Corp.
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