Valves and Valve Guides Inspection
Valves and Valve Guides InspectionReference: Valves and Cylinder Heads Removal and Installation
Reference: Valves and Cylinder Heads Disassembly and Reassembly
Valve Guides
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-to-guide clearance
Valves
^ Remove all carbon from valves.
^ Inspect each valve for wear, burn or distortion at its face and stem and, as necessary, replace it.
^ Measure thickness of valve head. If measured thickness exceeds limit, replace valve.
Valve specifications
^ Inspect valve stem end face for pitting and wear. If pitting or wear is found, valve stem end may be resurfaced. But do not grind its taper excessively. When valve is excessively worn out too much or its taper is gone, replace it.
^ Check each valve for radial runout with a dial gauge and "V" block.
To check runout, rotate valve slowly. If runout exceeds its limit, replace valve.
Valve head radial runout
Limit: 0.08 mm (0.003 inch)
^ 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 rotatingly tapping seat with valve head. Valve lapper (tool used in valve lapping) must be used.
Pattern produced on seating face of valve must be a continuous ring without any break, and the width of pattern must be within specified range.
^ 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.
a. Exhaust valve seat
Use valve seat cutters (1) to make two cuts as illustrated in figure. Two cutters must be used: the 1st for making 15° angle, and the 2nd for making 45° angle. The 2nd cut must be made to produce desired seat width.
Seat width for intake valve seat: 1.1 - 1.3 mm (0.0433 - 0.0512 inch)
b. Intake valve seat
Use valve seat cutters (1) to make three cuts as illustrated in figure. Three cutters must be used: the 1st for making 15° angle, the 2nd for making 60° angle, and the 3rd for making 45° angle. The 3rd cut (45°) must be made to produce desired seat width.
c. 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
