Sentra XE L4-1597cc 1.6L DOHC MFI (GA16DE) (1997)
Valve Guide: Testing and Inspection
CLEARANCE
1. Measure valve deflection as shown in illustration. The valve and valve guide mostly wear in this direction. The valve deflection limit (dial gauge
reading) is 0.2 mm (0.008 inch.)
2. If it exceeds the limit, check the valve to valve guide clearance.
a. Measure valve stem diameter and valve guide inner diameter.
b. Calculate valve to valve guide clearance. Valve to valve guide clearance equals (=) valve guide inner diameter minus (-) valve stem diameter:
Intake standard clearance is 0.020 - 0.050 mm (0.0008 - 0.0020 inch.)
Exhaust standard clearance is 0.040 - 0.070 mm (0.0016 - 0.0028 inch).
The limit for both the intake and exhaust is 0.1 mm (0.004 inch.)
c. If it exceeds the limit, replace valve and remeasure clearance.
3. If clearance still exceeds the limit after replacing valve, replace valve guide.