Technical data

7
General instructions
Angular tightening torque
For angular tightening torque the screw union is
tightened with a given torque, thereafter further
tightening with a predetermined angle. Example: at
90° angular tightening the union is tightened and an
additional
1/4 turn is made in a work procedure after the given
tightening torque has been reached.
In order to conduct satisfactory service work it is
therefore important that the correct type of sealant
and locking liquids are used for the unions where such
are required.
In the Workshop Manual we have indicated in
respective chapters the agents which are used in our
engine production.
During service work the same agent, or agent with
similar properties but of other manufacture, shall be
used.
When using sealants and locking liquids it is important
that the surfaces are free from oil, grease, paint and
anti-rust agent, and that they are dry.
Always follow the instructions of the manufacturer
concerning application temperature, hardening time
and other instructions for the product.
Two different basic types of agents are used on the
engine, and these are characterised by:
RTV-agent (Room temperature vulcanising). Most
often used with gaskets, e.g. sealing of gasket joints
or applied on gaskets. RTV-agent is fully visible when
the part has been dismantled: old RTV-agent must be
removed before the union is sealed again.
The following RTV-agents are named in the Workshop
Manual: Loctite® 574, Volvo Penta 840879-1,
Permatex®. No. 3, Volvo Penta 1161099-5,
Permatex® No. 77. Old sealant is removed in each
case with denatured spirit.
Anaerobic agents. These agents harden on the
absence of air. The agent is used when two solid
parts, e.g. cast components, are fitted together
without gasket. A common application is also to
secure and seal plugs, threads on pin bolts, taps, oil
pressure relays, etc. Hardened anaerobic agents are
transparent and therefore they are coloured to make
them visible. Hardened anaerobic agents are very
resistant to solvents and old agent cannot be
removed. Careful degreasing is conducted prior to
refitting, and new sealant is applied.
The following anaerobic agents are named in the
Workshop Manual: Loctite® 572 (white), Loctite® 241
(blue).
NOTE! Loctite® is a registered trade-mark for Loctite Corporation,
Permatex® is a registered trade-mark for Permatex Corporation.
Lock nuts
Dismantled lock nuts shall not be reused but replaced
with new items, since the locking properties diminish
or are lost with repeated use. For lock nuts with
plastic inserts, e.g. Nylock®, the tightening torque
given in the table shall be reduced if the Nylock® nut
has the same nut height as a standard full-metal
hexagonal nut. The tightening torque is reduced by
25% for screw size 8 mm or larger. For Nylock® nuts
with higher nut heights, where the full-metal thread is
equally high as a standard hexagonal nut, the
tightening torque as per the table are applicable.
Strength classes
Screws and nuts are divided into different strength
classes; affiliation is indicated by the marking on the
screw head. A higher number on the marking
represents a stronger material, e.g. a screw marked
10-9 has a higher strength than a screw marked 8-8. It
is therefore important when dismantling screw unions
that the screws are refitted in their original places. For
replacement of screws see the Parts Catalogue to
ensure that the correct version is obtained.
Sealants
A number of different sealants and locking liquids are
used on the engine. The properties of the mediums
differ, and they are intended for different union
strengths, temperature ranges, resistance to oils and
other chemicals, and for the different materials and
column sizes in the engine.