7
Tightening torques-protractor (angle)
tightening
Tightening using both a torque set-
ting and a protractor angle requires
that first the recommended torque is
applied using a torque wrench and
then the recommended angle is add-
ed according to the protractor scale.
Example: a 90° protractor tightening
means that the joint is tightened a
further 1/4 turn in one operation af-
ter the stated tightening torque has
been applied.
Locknuts
Do not re-use lock nuts that have been removed
during dismantling as they have reduced service life
when re-used - use new nuts when assembling or
reinstalling. For lock nuts with a plastic insert such
as Nylock
®
the tightening torque stated in the table
is reduced if the Nylock
®
nut has the same head
height as a standard hexagonal nut without plastic
insert. Reduce the tightening torque by 25% for bolt
size 8 mm or larger. Where Nylock
®
nuts are high-
er, or of the same height as a standard hexagonal
nut, the tightening 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 materi-
al, for example a bolt marked 10-9 indicates a high-
er tolerance than one marked 8-8. It is therefore im-
portant 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 trengths,
operating temperature ranges, resistance to oil and
other chemicals and for the different materials and
gap sizes in the engines.
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 en-
gine.
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 be-
fore applying sealant or locking fluid. Always follow
the manufacturer’s instructions for use regarding;
temperature range, curing time and any other in-
structions for the product.
Two 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. 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 ex-
ample cast components, are installed face-to-face
without a gasket. They are also commonly used to
secure plugs, threads in stud bolts, cocks, oil pres-
sure switches and so on. The cured material is
glass-like and it is therefore colored to make it vis-
ible. Cured anaerobic agents are extremely resist-
ant to solvents and the old agent cannot be re-
moved. When reinstalling the part is carefully
degreased and then new sealant is applied.
Summary of Contents for AQ125A
Page 1: ...Workshop Manual Engine Unit AQ125A B AQ145A B C 2 0 ...
Page 2: ......
Page 74: ...7739856 8 English 11 1998 ...