Volvo Penta 230, Руководство по ремонту

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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
added according to the protractor
scale. Example: a 90° protractor
tightening means that the joint is
tightened a further 1/4 turn in one
operation after 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 higher,
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 material,
for example a bolt marked 10-9 indicates a higher
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 strengths,
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 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; tempe-
rature 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 Ser-
vice Manual: Loctite
® 574, Volvo Penta 840879-1,
Permatex ® No. 3, Volvo Penta P/N 1161099-5, Perma-
tex ® No. 77. Old sealant can be removed using methy-
lated spirits in all cases.
Anaerobic agents. These agents cure in an absence of
air. They are used when two solid parts, for example
cast components, are installed face-to-face without a
gasket. They are also commonly used to secure
plugs, threads in stud bolts, cocks, oil pressure swit-
ches and so on. The cured material is glass-like and it
is therefore colored to make it visible. Cured anaer-
obic agents are extremely resistant to solvents and
the old agent cannot be removed. When reinstalling
the part is carefully degreased and then new sealant
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 Corpora-
tion, Permatex® is the registered trademark of the Permatex
Corporation.