Service manual

G420F(FE) Service Manual Chapter 3. Engine Mechanical System 68
Inspection
Cylinder Head
1. Check the cylinder head for crack, damage and
leak.
2. Clean out fur, adhesive and accumulated carbon
and after cleaning the oil passage, bleed the
passage with compressed air to check it for
clogging.
3. Using a square, check the cylinder head gasket
for flatness from shown in the illustration. If any
flatness is out of the limit, replace the cylinder
head or slightly cut the cylinder head gasket
surface.
Standard 0.03mm or less
Flatness of cylinder
Head gasket surface
Limit 0.06mm
Valve
1. Clean the valve with a wire brush.
2. Check each valve for wear and damage and
inspect the head and stem for torsion.
If the stem end is cave or worn, trim it.
At this time, trim it least.
Also, trim the valve surface.
If the margin is less than the limit, replace the
valve.
Valve margin
Intake 1.15mm
Standard
Exhaust 1.35mm
Intake 0.8mm
Limit
Exhaust 1.0mm