Man D 2842 LE 620 Repair Manual page 83

General notes
The sealing effect of the cylinder head seal depends mainly on whether the required initial tension of the
cylinder−head bolt is actually achieved and retained.
To tighten the cylinder−head bolts, use a calibrated torque wrench. The specified final torque must be main-
tained for at least 5 seconds when it is applied. When using snap−type torque wrenches, tighten the bolts
gradually as otherwise the torque selected will not be fully transferred to the bolts.
Observe the notes on the usability of cylinder−head bolts, tightening sequence, and prescribed tightening
method in the chapter "Service Data".
Tightening
"Tightening" is the initial tightening of the newly fitted bolts that have not yet been tightened following a re-
pair - e.g. after replacement of the cylinder head seal. Tighten the cylinder−head bolts with the engine cold,
i.e. the crankcase is hand−warm or colder.
Before inserting the cylinder−head bolts, apply engine oil to the thread (not the threaded hole) and coat the
seating surface of the bolt head with installation paste "Optimoly White T".
Do not use oils or oil additives containing MoS
In the case of unoiled bolts, a significant portion of the tightening torque is converted into friction and is thus
lost for the bolt pretensioning.
D To secure the cylinder heads, tighten the cylinder head bolts only slightly
D Align the cylinder heads by screwing on the straightedge (special tool).
If no straightedge is available, use the exhaust or intake pipe
D Tighten step by step in the right order and with the prescribed tightening torque and / or angle of rotation
Caution:
If individual bolts are tightened too much during preliminary tightening, the cylinder head is dis-
torted. The distortion can no longer be removed with continued tightening in accordance with re-
gulations!
Removing and installing the cylinder head
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