Volvo Penta 31 Series Workshop Manual page 9

Tightening torques-protractor
(angle) tightening
Tightening using both a torque setting and a protrac-
tor angle requires that first the recommended torque
is applied using a torque wrench and then the recom-
mended angle is added according to the protractor
scale. Example: a 90° protractor tightening means
that the joint is tightened a further 1/4 turn in one op-
eration after the stated tightening torque has been ap-
plied.
Locknuts
Do not re-use lock nuts that have been removed dur-
ing dismantling as they have reduced service life
when re-used - use new nuts when assembling or re-
installing. For lock nuts with a plastic insert such as
Nylock the tightening torque stated in the table is re-
®
duced if the Nylock nut has the same head height as
®
a standard hexagonal nut without plastic insert. Re-
duce the tightening torque by 25% for bolt size 8 mm
or larger. Where Nylock
same height as a standard hexagonal nut, the tighten-
ing torques given in the table apply.
Tolerance classes
Screws and nuts are divided into different strength
classes, the class is indicated by the number on the
bolt head. A high number indicates stronger material,
for example a bolt marked 10-9 indicates a higher tol-
erance than one marked 8-8. It is therefore important
that bolts removed during the disassembly of a bolted
joint must be reinstalled in their original position when
assembling the joint. If a bolt must be replaced check
in the replacement parts catalogue to make sure the
correct bolt is used.
Sealants
A number of sealants and locking liquids are used on
the engines. The agents have varying properties and
are used for different types of jointing strengths, oper-
ating temperature ranges, resistance to oil and other
chemicals and for the different materials and gap siz-
es in the engines.
nuts are higher, or of the
®
To ensure service work is correctly carried out it is
important that the correct sealant and locking fluid
type is used on the joint where the agents are re-
quired.
In this Volvo Penta Service Manual the user will find
that each section where these agents are applied in
production states which type was used on the engine.
During service operations use the same agent or an
alternative from a different manufacturer.
Make sure that mating surfaces are dry and free from
oil, grease, paint and anti-corrosion agent before ap-
plying sealant or locking fluid.
Always follow the manufacturer's instructions for use
regarding; temperature range, curing time and any
other instructions for the product.
Tow different basic types of agent are used on the
engine and these are:
RTV agent (Room temperature vulcanizing). Use for
gaskets, sealing gasket joints or coating gaskets.
RTV agent is clearly visible when a component has
been dismantled; old RTV must be removed before
the joint is resealed.
The following RTV agents are mentioned in the Serv-
ice Manual: Loctite ® 574, Volvo Penta 840879-1, Per-
matex No. 3, Volvo Penta P/N 1161099-5, Perma-
®
tex ® No. 77. Old sealant can be removed using
methylated spirits in all cases.
Anaerobic agents. These agents cure in an absence
of air. They are used when two solid parts, for exam-
ple cast components, are installed face-to-face with-
out a gasket. They are also commonly used to se-
cure plugs, threads in stud bolts, cocks, oil pressure
switches and so on. The cured material is glass-like
and it is therefore colored to make it visible. Cured
anaerobic agents are extremely resistant to solvents
and the old agent cannot be removed. When reinstall-
ing the part is carefully degreased and then new seal-
ant is applied.
The following anaerobic agents are mentioned in the
Service Manual: Loctite
(blue).
NOTE! Loctite® is the registered trademark of Loctite Corpora-
tion, Permatex® is the registered trademark of the Permatex
Corporation.
Repair instructions
® 572 (white), Loctite ® 241
7