Valve and Valve Guide Inspection
Valve and Valve Guide InspectionReference: Valve and Cylinder Head Disassembly and Reassembly
Valve Guide
Valve stern-to-guide clearance
^ Using a micrometer and bore gauge, take diameter readings on valve stems and guides to check stem-to-guide clearance.
^ Be sure to take reading at more than one place along the length of each stem and guide.
^ If clearance exceeds limit, replace valve and valve guide.
Valve stem outside diameter
IN: 5.465 - 5.480 mm (0.2152 - 0.2157 in.)
EX: 5.440 - 5.455 mm (0.2142 - 0.2147 in.)
Valve guide inside diameter
IN & EX: 5.500 - 5.512 mm (0.2166 - 0.2170 in.)
Stem-to-guide clearance
Standard
IN: 0.020 - 0.047 mm (0.0008 - 0.0018 in.)
EX: 0.045 - 0.072 mm (0.0018 - 0.0028 in.)
Limit
IN: 0.070 mm (0.0027 in.)
EX: 0.090 mm (0.0035 in.)
Valve stem end deflection
Check valve stem end deflection using a dial gauge.
Move stem end in directions (1) and (2) to measure end deflection.
If deflection exceeds its limit, replace valve and valve guide.
Valve stem end deflection limit
In: 0.14 mm (0.0055 in.)
Ex: 0.18 mm (0.0070 in.)
Valve
Visual inspection
^ Remove all carbon deposits from all valves (1).
^ Check each valve for wear, burn or distortion at its face and stem end.
Replace it if necessary.
^ Measure valve protrusion length "a".
If measured length is out of standard value, replace valve.
Valve protrusion length "a
Standard
IN: 44.00 - 44.60 mm (1.733 - 1.755 in.)
EX: 43.55 - 44.15 mm (1.715 - 1.738 in.)
Valve head radial runout
Check each valve for radial runout using a dial gauge and "V" block.
To check runout, rotate valve slowly.
If runout exceeds its limit, replace valve.
Valve head radial runout
Standard
IN: 0.000 - 0.045 mm (0.0000 - 0.0017 in.)
EX: 0.000 - 0.030 mm (0.0000 - 0.0011 in.)
Limit
IN: 0.090 mm (0.0035 in.)
EX: 0.060 mm (0.0023 in.)
Seating contact width
Create contact pattern on each valve in the usual manner, i.e., by giving uniform coat of marking compound to valve seat and by rotating tapping seat with valve head. Valve lapper (tool used in valve lapping) must be used.
Pattern produced on seating surface of valve must be a continuous ring without any break, and the width of pattern must be within specified range.
Standard seating width "a" revealed by contact pattern on valve face
IN: 1.05 - 1.35 mm (0.0414 - 0.531 in.)
EX: 1.12 - 1.42 mm (0.0441 - 0.0559 in.)
Valve seat repair
A valve seat not producing a uniform contact with its valve or showing width of seating contact that is out of specified range must be repaired by regrinding or by cutting and regrinding and finished by lapping.
1) Intake valve seat:
Use valve seat cutters to make three cuts as illustrated in figure. Three cutters must be used: the 1st for making 22° angle, the 2nd for making 60° angle, and 3rd for making 45° angle. The 3rd cut (45°) must be made to produce desired seat width.
Seat width for intake valve seat
"a": 1.05 - 1.35 mm (0.0414 - 0.0531 in.)
2) Exhaust valve seat:
Use valve seat cutters to make three cuts as illustrated in the figure. Three cutters must be used: the 1st for making 22° angle, the 2nd for making 65° angle, and 3rd for making 45° angle. The 3rd cut must be made to produce desired seat width.
Seat width for exhaust valve seat
"b": 1.12 - 1.42 mm (0.0441 - 0.0559 in.)
3) Valve lapping:
Lap valve on seat in two steps, first with coarse size lapping compound applied to face and the second with fine-size compound, each time using valve lapper according to usual lapping method.
Venturi Plug Inspection
Check that venturi plug passage is not clogged.
If venturi plug passage is clogged, clean or replace venturi plug.
