Hitachi EX20UR-2 Manual page 337

CYLINDER HEAD
Cylinder head
Remove carbon deposit on bottom surface of head with
a care not to damage the valve seat. Also, check each
part for presence of damage using a flaw detective
agent.
Leakage: Water pressure test 5 kg/cm' (3 minutes)
Distortion of bottom surface
Measure distortion in diagonal directions using a straight
edge and thickness gauge.
(mm)
Standard
Value requiring
repair
Repair method
0.075 or less 0.15 or more
Repair with a grinder
within a total ground
amount 0.3 of cylinder
head and body.
In this case, the gasket
must be replaced.
ENGINE/Engine
W05-02-21