Man D 2840 LE 301, Repair Manual

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Removing and installing cylinder head
97
General notes
The sealing effect of the cylinder head gasket largely depends on whether the required initial tension for the
cylinder head bolts is reached and maintained.
Use calibrated torque wrenches to tighten the cylinder head bolts. When the specified final torque is applied
it must be maintained for at least 5 seconds. When using snap-type torque wrenches tighten bolts gradually
since otherwise the torque selected will not be fully transferred to the bolts.
Observe notes on usability of cylinder head bolts, order of tightening and specified tightening method in
publication “Service Data”.
Tightening
“Tightening” is defined as the first − time tightening of newly fitted bolts that have not been tightened after a
repair, e.g. changing the cylinder head gasket. Tighten cylinder head bolts while the engine is cold, i.e. the
crankcase is warm to the touch or colder.
Before inserting the cylinder head bolts, apply engine oil to the thread (not to the threaded hole) and “Opti-
moly White T” assembly paste to the contact faces of the bolt heads.
Do not use oil or oil additives containing MoS
2
.
If the bolts are not oiled, a significant amount of the tightening torque is converted into friction and thus lost
for the bolt pretensioning.
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To position cylinder heads, tighten cylinder head bolts only lightly.
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Align cylinder heads by screwing on the steel ruler (special tool). If a steel ruler is not available, use ex-
haust or intake manifold.
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Tighten bolts in specified order and to specified torque / tightening angle in steps.
Caution:
If during initial tightening some bolts are excessively tightened, the cylinder head will be distorted.
This distortion cannot be cancelled out by continuing to tighten according to the instructions.