8
General instructions
Protractor tightening torques
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 rec-
ommended angle is added according to the protrac-
tor 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 8
mm bolt sizes or larger. Where Nylock
®
nuts are
higher, or of the same height as a standard hexago-
nal nut, the tightening torques given in the table ap-
ply.
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 materi-
al, for example a bolt marked 10-9 indicates a high-
er strength 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.
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, operating temperature ranges, resistance
to oil and other chemicals and for the different ma-
terials 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.
Ensure that mating surfaces are dry and free from
oil, grease, paint and anti-corrosion agent before
applying sealant or locking fluid.
Always follow the manufacturer’s instructions for
use regarding; temperature range, curing time and
any other instructions for the product.
Two different basic types of agent are used on the
engine. These are:
RTV agent (Room temperature vulcanizing). Used
for gaskets, sealing gasket joints or coating gas-
kets. RTV agent is clearly visible when a compo-
nent has been dismantled; old RTV must be re-
moved before the joint is resealed.
The following RTV agents are mentioned in the
Service Manual: Loctite
®
574, Volvo Penta 840879-
1, Permatex
®
No.3, Volvo Penta P/N 1161099-5, Permatex
(r)
No.
77. Old sealant can be removed using denatured al-
cohol 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. Used to seal and lock plugs, stud
threads, stopcocks, oil pressure sensors etc. Cured
anaerobic agents are glassy and the agents are
colored to make them visible. Cured anaerobic
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 Corporation,
Permatex® is the registered trademark of the Permatex Corpora-
tion.
Summary of Contents for MD22
Page 1: ...Engine repair MD22 TMD22 TAMD22 Workshop Manual 2 0 A ...
Page 2: ......
Page 129: ...127 Notes ...
Page 130: ...128 Notes ...
Page 132: ...7738684 5 English 04 1999 ...