ENGINE
3-12
Service limit
0.03 mm (0.0012 in)
VALVE HEAD RADIAL RUNOUT
Place a dial gauge as shown and measure valve head
radial runout.
If the service limit is exceeded, replace the valve.
Valve head radial
runout
Dial gauge : 09900-20606
Magnetic stand : 09900-20701
V-block : 09900-21304
Dial gauge : 09900-20606
Magnetic stand : 09900-20701
Micrometer(0~25 mm) : 09900-20201
Standard
0.010
0.037 mm
(0.0004
0.0015 in)
0.030
0.057 mm
(0.0012
0.0022 in)
Valve stem diameter
IN.
EX.
Standard
4.975~4.990 mm (0.1959 0.1965 in)
4.955~4.970 mm (0.1951 0.1957 in)
VALVE STEM DIAMETER
Measure the valve stem outside diameter.
If the diameter measured exceeds the standard, replace
the valve.
VALVE GUIDE-VALVE STEM CLEAR-
ANCE
Measure the clearance in the valve guide-valve stem, by
rigging up the dial gauge as shown. If the clearance is
measured exceeds the limit specified below, then deter-
mine whether the valve or the guide should be replaced
to reduce the clearance to within the standard range:
Service limit
41.65 mm (1.64 in)
Valve spring free
length(IN. & EX.)
Venier calipers : 09900-20101
VALVE SPRING
The force of the coil spring keeps the valve seat tight. A
weakened spring results in reduced engine power out-
put and often accounts for the chattering noise coming
from the valve mechanism.
Check the valve springs for proper strength by measur-
ing their free length and also by the force required to
compress them. If the spring length is less than the ser-
vice limit or if the force required to compress the spring
does not fall within the specified range, replace both the
inner and outer springs as a set.
Valve guide-valve stem clearance
IN.
EX.