Valve and Valve Guide Inspection

Valve and Valve Guides Inspection

Valve Guide

Valve stem-to-guide clearance
Using 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 cylinder head.
Valve stem and valve guide specification








Valve stem end deflection
If bore gauge is not available, check end deflection of valve stem with a dial gauge instead. Move stem end in directions (1) and (2) to measure end deflection.
If deflection exceeds its limit, replace valve stem and cylinder head.
Valve stem end deflection limit
In: 0.14 mm (0.0055 in.)
Ex: 0.18 mm (0.0071 in.)





Valve

Visual inspection
^ Remove all carbon from valves (1).
^ Inspect each valve for wear, burn or distortion at its face and stem end, as necessary, replace it.
^ Measure each valve installation height.
If measured height exceeds specification, replace valve.
Valve installation height
IN & EX: 35.23 - 36.69 mm (1.3870 - 1.4445 in.)








Valve head radial runout
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
Standard: 0 - 0.038 mm (0 - 0.0015 in.)
Limit: 0.05 mm (0.0020 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 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.
Standard seating width "a" revealed by contact pattern on valve face
Intake: 1.0 - 1.4 mm (0.0394 - 0.0551 in.)
Exhaust: 1.4 - 1.8 mm (0.0551 - 0.0709 in.)





Valve seat repair
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) Use valve seat cutters (1) to make three cuts as illustrated in figure. Three cutters must be used: the 1st for making 30 degrees angle, the 2nd for making 60 degrees angle, and 3rd for making 45 degrees angle. The 3rd cut (45 degrees) must be made to produce desired seat width.
Seat width for valve seat "a"
Intake: 1.0 - 1.4 mm (0.0394 - 0.0551 in.)
Exhaust: 1.4 - 1.8 mm (0.0551 - 0.0709 in.)
2) 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.











Oil relief valve
Check that oil relief valve in not clogged.
If oil relief valve is clogged, clean or replace oil relief valve.