Doosan G420F Service Manual page 114

Piston Pins
1. Measure the diameter of the piston pin.
Piston pin diameter
20.001~20.006 mm (0.7874 ~ 0.7876in.)
2. Measure the piston pin-to-piston clearance.
Piston pin-to-piston clearance
0.01 ~ 0.02 mm (0.0004 ~ 0.0008in.)
3. Check the difference between the piston pin
diameter and the connecting rod small end
diameter.
Piston pin-to-connecting rod interference
0.016 ~ 0.032 mm (0.00063 ~ 0.00126in.)
G420F(FE) Service Manual
Reassembly
NOTE: Thoroughly clean all parts to assembled.
Before installing the parts, apply fresh engine oil to
all sliding and rotating surfaces. Replace all gaskets,
O-rings and oil seals with new parts.
1. Assemble piston and connecting rod.
1) Use a hydraulic press for installation.
2) The piston front mark and the connecting rod
front mark must face the timing belt side of the
engine.
2. Install piston rings.
1) Install the oil ring expander and 2 side
rails by hand.
2) Using a piston ring expander, install the
2compression rings with the code mark facing
upward.
3) Position the piston rings so that the
ring ends are as shown.
113 Chapter 3. Engine Mechanical System