7
General instructions
Tightening torques-protractor
(angle) tightening
Tightening using both a torque setting and a protractor
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 ope-
ration after the stated tightening torque has been app-
lied.
Sealing compound
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, ope-
rating temperature ranges, resistance to oil and other
chemicals and for the different materials and gap si-
zes in the engines.
To ensure service work is correctly carried out it is im-
portant that the correct sealant and locking fluid type
is used on the joint where the agents are required.
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 app-
lying sealant or locking fluid.
Always follow the manufacturer’s instructions for use
regarding; temperature range, curing time and any oth-
er 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 Servi-
ce Manual: Loctite
®
574, Volvo Penta 840879-1, Per-
matex
®
No. 3, Volvo Penta P/N 1161099-5, Permatex
®
No. 77.
Old sealant can be removed using denatured alcohol
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 wit-
hout a gasket. They are also commonly used to secu-
re 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 reinstal-
ling the part is carefully degreased and then new sea-
lant is applied.
The following anaerobic agents are mentioned in the
Service Manual: Loctite
®
572 (white), Loctite
®
241
(blue).
NOTE! Loctite® is the registered trademark of Loctite Corporation,
Permatex® is the registered trademark of the Permatex Corpora-
tion.
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 re-
duced if the Nylock
®
nut has the same head height as
a standard hexagonal nut without plastic insert. Redu-
ce the tightening torque by 25% for bolt size 8 mm or
larger. Where Nylock
®
nuts are higher, or of the same
height as a standard hexagonal nut, the tightening tor-
ques given in the table apply.
Strength 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 tole-
rance 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.
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