1D-30 Engine Mechanical:
Valve Stem Deflection
Lift the valve about 10 mm (0.39 in) “a” from the valve
seat. Measure the valve stem deflection in two
directions, “X” and “Y”, perpendicular to each other.
Position the dial gauge as shown. If the deflection
exceeds the service limit, then determine whether the
valve or the guide should be replaced with a new one.
Special tool
(A): 09900–20606 (Dial gauge (1/100 mm))
(B): 09900–20701 (Magnetic stand)
Valve stem deflection (IN & EX)
Service limit: 0.35 mm (0.014 in)
Valve Stem Diameter
Measure the valve stem O.D. using the micrometer. If it
is out of specification, replace the valve with a new one.
If the valve stem O.D. is within specification but the valve
stem deflection is not, replace the valve guide. After
replacing the valve or valve guide, recheck the
deflection.
Special tool
(A): 09900–20205 (Micrometer (0 – 25 mm))
Valve stem O.D.
Standard (IN): 4.475 – 4.490 mm (0.1762 – 0.1768 in)
Standard (EX): 4.455 – 4.470 mm (0.1754 – 0.1760 in)
NOTE
If valve guides have to be removed for
replacement after inspecting related parts,
carry out the steps shown in valve guide
replacement. Refer to “Valve Guide
Replacement (Page1D-32)”.
Valve Springs
The force of the coil spring keeps the valve seat tight.
Weak-ened spring result in reduced engine power
output, and often account for the chattering noise
coming from the valve mechanism.
Check the valve spring for proper strength by measuring
its free length and also by the force required to compress
it.
If the spring length is less than the service limit, or if the
force required to compress the spring does not fall within
the range specified, replace the spring.
Special tool
(A): 09900–20102 (Vernier calipers)
Valve spring free length (IN & EX)
Service limit: 38.6 mm (1.52 in)
Valve spring tension (IN & EX)
Standard: 137.3 N (14.0 kgf, 30.1 lbs) 33.35 mm
(1.313 in)
(A)
(B)
“X”
“Y”
I705H1140057-02
I310G1140110-01
Tension “a” Length “b”
137.3 N
(14.0 kgf, 30.1 lbs)
33.35 mm
(1.313 in)
(A)
I649G1140237-02
“a”
“b”
I649G1140238-02
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