Engine Mechanical: 1D-45
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): 09900–20607 (Dial gauge (1/100 mm, 10
mm))
(B): 09900–20701 (Magnetic stand)
Valve stem deflection (IN. & EX.)
Service limit: 0.35 mm (0.014 in)
Valve Stem Wear
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 (Page 1D-47)”.
Valve Spring
The force of the coil spring keeps the valve seat tight. A
weakened spring results in reduced engine power output
and often accounts for the chattering noise coming from
the valve mechanism.
Check the valve springs for proper strength by
measuring their free length and also by the force
required to compress them. If the spring length is less
than the service limit or if the force required to compress
the spring does not fall within the specified range,
replace the valve spring.
Special tool
(A): 09900–20102 (Vernier calipers (1/20 mm,
200 mm))
Valve spring free length (IN. & EX.)
Service limit: 39.6 mm (1.56 in)
Valve spring tension (IN. & EX.)
Standard: Approx. 147 N (15.0 kgf, 33.1 Ib-ft)/36.0
mm (1.42 in)
(A)
(B)
“X”
“Y”
I718H1140121-01
(A)
I718H1140122-01
(A)
I649G1140237-03
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