GMC 1976 ZEO 6083 Maintenance Manual page 691

24C- 1 4 ONAN MOTOR GENERATOR
THESE MARKS MUST
ALIGN WHEN INSTALL-
ING TIMING GEARS .
A-1600
1 . Drain oil.
Figure 11-Timing Gear
2. Remove the cylinder heads and oil base pan
from the engine .
3. Remove the ridge from the top of each .cylinder
with a ridge reamer before attempting piston re-
moval (figure 12). Forcing the piston from the cylin
der before reaming may cause damage to the piston
lands.
4. Turn the crankshaft until the piston is at the
bottom of its stroke and remove the connecting rod
bolts: Lift the rod bearing cap from the rod and push
the rod and piston assembly out through the top of
the cylinder using a hammer handle . Avoid scratch-
ing the crankpin and cylinder wall when removing
the piston and rod.
Figure 12-Removing Ridge From The Cylinder
Removal and Installation
NOTE :
Mark each piston and rod assembly so
they can be returned to their respective cylinders
after overhaul . Keep connecting rod bearing
caps with their respective rods .
5. Remove the piston rings from the piston with
a piston ring spreader as shown in Figure 13 .
Remove the piston retainer and push the piston pin
out.
CLEANING
Remove dirt and deposits from the piston sur-
faces with an approved cleaning solvent. Clean the
piston ring grooves with a groove cleaner or the end
of a piston ring filed to a sharp point (figure 14). Care
must be taken not to remove metal from the groove
sides.
NOTE :
Do not use a caustic cleaning solvent or
wire brush for cleaning pistons .
Figure 13-Removing Piston Rings