Maintenance of Major Components
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5.7. Tightening Cylinder Head Bolts
1) Retightening cylinder head bolts on new engines
by authorized specialist personnel (engine cold or warm)
The cylinder heads are mounted with
cylinder head bolts which are tightened by
the angle-of-rotation method. On new
engines the cylinder head bolts are
tightened up for the first time at the factory
after the engine has been broken in.
After the first 400 hours of operation
retighten cylinder head bolts 1 to 4 in the
order shown in right figure by a further 90
°
(1/4 revolution).
The two outer screws (intake and exhaust
sides) must not be retightened.
NOTE :
The cylinder head bolts to be retightened must not be loosened first, but simply
tightened by a further 90
°
(1/4 revolution) from their actual position.
2) 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 “Optimoly 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.
z
1st pretightening step = to 10 N
⋅
m
z
2nd pretightening step = to 80 N
⋅
m
z
3rd pretightening step = to 150 N
⋅
m
z
4th pretightening step = turn by 90
°
z
Final tightening = turn by 90
°
1
Intake side injector
Exhaust side
4
3
2
EA6O6009
1
Intake side injector
Exhaust side
4
3
5
6
2
EA6O6010
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