6.3. Tightening Cylinder Head Bolts
1) Tightening cylinder head bolts after a repair by authorized specialist personnel
(engine cold)
Before inserting the cylinder head bolts
oil them with engine oil on the thread
(not to the bore) and coat the contact
face of the bolt head with "Optimal
White T" assembly paste. Do not use
any oils or oil additives that contain
MoS
2
.
The bolts must be tightened by the
angle-of-rotation method as shown in
right figure.
•
1st pre-tightening step = to 8 kg.m
•
2nd pre-tightening step = to 15 kg.m
•
3rd pre-tightening step = turn by 90
˚
•
Final tightening = turn by 90
˚
NOTE : When a cylinder head has been removed the cylinder head gasket must always be
changed.
2) Standard and repair length of cylinder head bolts
•
Checking
Re-using old cylinder head bolts check them ad follows;
•
Length
During tightening the bolts are intentionally stressed beyond the yield point and therefore
subjected to some permanent elongation each time they are tightened.
•
Surface
The surface of the bolts must be in satisfactory condition, i.e. The phosphate coating must
be intact and there must be no rust.
Rusted or damaged bolts or bolts elongated beyond the maximum permissible length must
immediately be made unusable i.e. by destroying the threads with a hammer and scrapped.
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1
Intake side injector
Exhaust side
4
3
5
6
2
EA6O6010
EOA11115
L
Standard
Permissible
Bolt No.
length "L" on
maximum repair
new bolts
length (mm)
(mm)
3, 6
168
171
2, 4, 5
144
147
1
109
112
