Valve-to-Guide Clearance Measurement (Wobble
If a small bore gauge is not available, inspect the valve
guide wear by measuring the valve to valve guide clearance
with the wobble method as indicated below.
Insert a new valve [A] into the guide [B] and set a dial
gauge against the stem perpendicular to it as close as
possible to the cylinder head mating surface.
Move the stem back and forth [C] to measure valve/valve
Repeat the measurement in a direction at a right angle to
If the reading exceeds the service limit, replace the guide.
The reading is not actual valve/valve guide clearance
because the measuring point is above the guide.
Valve/Valve Guide Clearance (Wobble Method)
0.09 ∼ 0.16 mm (0.0035 ∼ 0.0063 in.)
0.03 ∼ 0.10 mm (0.0012 ∼ 0.0039 in.)
0.36 mm (0.014 in.)
0.29 mm (0.011 in.)
Valve Seat Inspection
Remove the valve (see Valve Removal).
Check the valve seating surface [A] between the valve [B]
and valve seat [C].
Measure the outside diameter [D] of the seating pattern
on the valve seat.
If the outside diameter is too large or too small, repair the
seat (see Seat Repair).
Valve Seating Surface Outside Diameter
24.7 ∼ 24.9 mm (0.972 ∼ 0.980 in.)
28.9 ∼ 29.1 mm (1.138 ∼ 1.146 in.)
Measure the seat width [E] of the portion where there is
no build-up carbon (white portion) of the valve seat with a
If the width is too wide [G], too narrow [H] or uneven [J],
repair the seat (see Valve Seat Repair).
Valve Seating Surface Width
0.8 ∼ 1.2 mm (0.031 ∼ 0.047 in.)
0.5 ∼ 1.0 mm (0.020 ∼ 0.039 in.)
ENGINE TOP END 5-31