Pistons And Connecting Rods - Onan T260G Service Manual

CRANKSHAFT
GEAR PULLER
INSTALLING TIMING
FIGURE 11. TIMING GEAR REMOVAL AND INSTALLATION
PISTONS AND CONNECTING RODS
Observe the following procedure when removing
pistons and connecting rods from the engine.
1. Drain oil.
2. Remove the cylinder head and oil base pan from
the engine.
3.
Remove the ridge from the top of each cylinder
with a ridge reamer before attempting piston
removal (Figure 12).
CAUTION
Forcing the piston from the
cylinder before reaming may
cause damage to the piston lands and break
rings.
FIGURE 12. REMOVING RIDGE FROM CYLINDER
4. Turn the crankshaft until the piston is at the
bottom of its stroke and remove the connecting
rod nuts. 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. A v o i d
scratching the crankpin and cylinder wall whel
removing the piston and rod.
5. 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.
6. Remove the piston rings from the
piston with a
piston ring spreader (Figure 13). Remove the piston
pin retainer and push the piston pin out.
FIGURE
13.
REMOVING PISTON RINGS
7 . Remove dirt and deposits from the piston surfaces
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:
CAUTION
These materials will cause piston damage.
Do not use a caustic cleaning solvent
or wire brush for cleaning pistons.
When cleaning the connecting rods in solvent, be sure
to include the rod bore. Blow out all passages with
compressed air.
Engines that have been fitted with 0.005 inch (0.1 3 mm)
oversize pistons at the factory are identified by the letter
E after the serial number. Number is stamped on t h e
cylinder block and on the unit nameplate.
10-8