Yanmar 4LHA-DTP, Operation Manual

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Chapter 2 Basic Engine
4. Cylinder Head
,4LHA Ser
4-5 Assembling the cylinder head
Partially tighten the bolts in the specified order and then
tighten to the specified torque, being careful not to distort the
head.
(1) Clean out the cylinder head bolt holes.
(2) Check for foreign matter on the cylinder head surface
where it comes in contact with the block.
(3) Coat the head bolt threads and nut seats with lube oil.
(4) Use the positioning pins to line up the head gasket with the
cylinder block.
(5) Match up the cylinder head with the head gasket and
mount.
Exhaust manifold side
Intake manifold side
4 Cylinder engine
mn
Top clearance
4LHA-
DTE/DTZE/DTP/DTZP
STE/STZE/STP/STZP
4LHA-
HTE/HTZE/HTP/HTZP
0.71-0.89
0.81-0.99
(When head gasket thickness 1.35mm)
N*m(kgf-m)
First Second Final
Tightening torque
108
(11)
167
(17)
206
(21)
(Head bolt size : M13X1.5), Apply engine oil to the thread and
seat surface
4-6 Measuring top clearance
(1) Place a high quality fuse (<P 1.5mm(0.0591 in.), 10mm
(0.3937 in.) long) in three positions on the fiat part of
the piston head.
(2) Assemble the cylinder head gasket and the cylinder
block and tighten the bolts in the specified order to the
specified torque.
(3) Tum the crank, (in the direction of engine revolution),
and press the fuse against the piston until it breaks.
(4) Remove the head and take out the pressed fuse.
(5) Measure the three positions where each fuse is
pressed and calculate the average.
4-7 Intake and exhaust valve rocker arms
Valve rocker arm and valve rocker arm bushing wear may altei
opening/ closing timing of the valve, and may in turn affec
engine performance according to the extent of the change.
2-19