Mitsubishi S4Q, User Manual

Page: 23 / 174

23 / 174 Service Manual Mitsubishi SQ-Series diesel engines
Version 08/2004
CYLINDER HEADS AND VALVE
MECHANISM
ENGLISH
ENGINE MAIN PARTS
7.1.7 Measuring piston protrusion
1) Determine the top dead center of the piston
with a dial indicator.
2) Install a dial indicator on the crankcase with its
point on the top of the piston. Set the indicator
to read 0 (zero).
3) Check the piston protrusion at three points on
the top of the piston, as shown in the
illustration, and average the three
measurements to determine the protrusion.
Subtract the projection from the compressed
thickness of the gasket to determine the
clearance between the piston top and the
cylinder head.
If the piston protrusion is not correct, check
the various parts for clearance.
Unit: mm [in.]
Figure 15 Measuring piston protrusion
Item Assembly Standard
Piston protrusion
0.13 to 0.60
[0.0051 to 0.0236]
Compressed thickness of
gasket 1.27 to 1.35
[0.0500 to 0.0531]
CAUTION
Incorrect piston protrusion affects engine
performance and causes valve interference with
piston.