Mitsubishi 4G1 series, Service Manual

Page: 378 / 522

ENGINE Cvlinder Head and Valve SOHC
1
1
VALVE SPRINGS
Measure the free height of the spring and, if it is smaller
than the limit, replace.
Standard value:
SOHC
49.8 mm (1.961 in.)
DOHC
up to
1992 models 45.2 mm (1.780 in.)
From 1993 models
46.4 mm (1.827 in.)
Limit:
SOHC
48.8 mm (1.921 in.)
DOHC
up to
1992 models
44.2 mm in.)
From 1993 models
45.4 mm (1.878 in.)
(2) Measure the squareness of the spring and, if the limit is
exceeded, replace.
Standard value:
Limit: 4”
VALVE GUIDES
(1) Measure the clearance between the valve guide and valve
stem. If the limit
is
exceeded, replace the valve guide or
valve, or both.
Standard value:
Intake 0.03 0.06 mm in.)
Exhaust
0.05 0.09 mm in.)
Limit
Intake
0.10 mm in.)
Exhaust
0.15 mm in.)
VALVE SEAT RECONDITIONING PROCEDURES
(1) Before valve seat reconditioning, check the valve
guide clearance.
(2) Recondition the valve seat with a seat grinder or cutter. The
valve seat width should be the specified value at the center
of the valve face.
Inspect the valve seat with prussian blue to determine
where the valve contacts the seat. To do this, coat the valve
seat lightly with prussian blue, and then set the valve in
place.
Rotate the valve with a light pressure. If the blue is
transferred to the center of the valve face, contact is
satisfactory.
If the blue is transferred to the top edge of the valve face,
lower the valve seat with a 30 degrees stone or cutter. If
the
blue is transferred to the bottom edge of the valve face,
raise the valve seat with a 65 degrees stone or cutter.
Valve seat diameter:
Intake 44 mm (1.73 in.)
Exhaust 38 mm (1.50 in.)
Seat width: 0.9 1.3 mm in.)
(3) The valve and valve seat should be lapped with lapping
compound.
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