Service manual

G420F(FE) Service Manual Chapter 3. Engine Mechanical System 96
Disassembly
1. Remove the cylinder head assembly.
NOTE: Put an identification mark on the connecting
rod and cap before disassembly to refer to the
original position and direction.
2. Remove the oil pan and remove the oil screen.
3. After removing the connecting rod cap, remove
the piston and connecting rod assembly from the
cylinder. Arrange the connecting rod bearing in
cylinder number order.
4. Using the special tool piston pin setting tool
(09234-33001), disassemble the piston from the
connecting rod as below.
1) Remove the piston ring.
2) When placing the assembly on a press, face
the front mark on the piston upward.
3) Using the press, remove the piston pin.
Inspection
Piston and Pistonpin
1. Check the piston for scratch, wear, etc. and
replace it if necessary.
2. Check the piston ring for break, damage and
abnormal wear and replace it if necessary. When
replacing the piston, the ring should be replaced
also.
3. Check that the piston pin is inserted in the piston
hole and replace the piston and pin if necessary.
Piston should be smoothly pressed at normal
room temperature.
Piston Ring
1. When measuring the side clearance of piston ring,
if the measured value is out of the limit, insert a
new ring to the ring groove and re-measure the
side clearance.
Item
Specified
value
Limit
No.1 0.04 ~ 0.08mm 0.1mm
Side clearance
of piston ring
No.2 0.03 ~ 0.07mm 0.1mm
2. To measure the end gap of piston ring, insert the
piston ring to the cylinder bore. At this time,
smoothly insert the ring to the piston so as to
place the ring and cylinder wall to right position.
After this, smoothly insert the ring to the piston.
And then, pull out the piston upward and measure
gap using a feeler gauge. When the gap exceeds
the limit, re-place the piston ring.