GMC 1976 ZEO 6083 Maintenance Manual page 693

24C- 1 6 ONAN MOTOR GENERATOR
Figure 17-Checking Ring End Gap
CYLINDER BLOCK
INSPECTION :
Figure 18-Methods of Measuring The Diameter of a Cylinder
1 . Make a thorough check for cracks . Small
cracks may be detected by coating the suspected area
with a mixture of 25% kerosene and 75% light mo
tor oil. Wipe the part dry and immediately apply a
coating of zinc oxide (white lead) dissolved in wood
alcohol. If cracks are present, the white coating will
become discolored at the defective area .
2. Inspect the cylinder bore for scoring. Check
the Welsh plugs for a tight, even fit and fins for
breakage .
3 . Check the cylinder bore for taper, out of round
and wear, with a cylinder bore gauge, telescope
gauge or inside micrometer (figure 18). These meas
urements should be taken at four places - the top
and bottom of piston ring travel .
4. Record measurements taken lengthwise at the
top and bottom of the piston travel as follows:
a. Lengthwise of the block, measure and re-
cord as "A" the diameter of the cylinder at the top
of the cylinder where greatest ring wear occurs .
b. Also, lengthwise of the block, measure and
record as "B" the cylinder diameter at the piston
skirt travel .
c. Crosswise of the block, measure and record
as "C" the diameter of the top of the cylinder at the
greatest point of wear .