Assembling The Cylinder Head; Measuring Top Clearance - Yanmar 3JH4E Service Manual

5. Inspection and Servicing of Basic Engine Parts
6) Spring retainer and spring cotter
Inspect the inside face of the spring retainer, the
outside surface of the spring cotter, the contact
area of the spring cotter inside surface and the
notch in the head of the valve stem. Replace the
spring retainer and spring cotter when the contact
area is less than 70%, or when the spring cotter
has been recessed because of wear.

5.2.5 Assembling the cylinder head

Partially tighten the bolts in the specified order and then
tighten to the specified torque, being careful that the
head does not get distorted.
(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.
Cylinder head bolt
tightening torque

5.2.6 Measuring top clearance

(1) Place a high quality fuse (
long) in three positions on the flat 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) Turn 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 broke fuse.
(5) Measure the three positions where each fuse is broken and calculate the average.
Top clearance
N•m (kgf•m)
First Second
44-54 85.2-91.2
(4.5-5.5) (8.69-9.30)
1.5mm, 10mm
Ø
0.68-0.80
Disassembly
8
2
12
10
4
6
Head bolt disassembly order
(3 cylinder head)
Assembly
7
13
11
9
Head bolt tightening order
(3 cylinder head)
Fuse wire
mm
102
Camshaft side
14 5
9 3
11
1
13 7
Camshaft side
1 10
12
3 6
5 4 14
2
8