Group 23 EMS 2 Repair instructions
7
Torque-angle tightening
In torque/angle tightening, the fastener is tightened to
the specified torque, and tightening then continues
through a pre-determined angle. Example: for 90° an-
gle tightening, the joint is turned a further 1/4 turn in
one sequence, after the specified tightening torque
has been achieved.
Lock nuts
Disassembled locknuts shall not be re-used, they
shall be replaced by new ones, since the locking prop-
erties are impaired or lost when the nut is used sever-
al times. For lock nuts with a plastic insert such as
Nylock
®
the 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
torque by 25% for screw size 8 mm or larger. Where
Nylock
®
nuts are higher, where the metallic thread is
of the same height as a standard hexagonal nut, the
torques given in the as shown in table apply.
Strength classes
Screws and nuts are sub-divided into different
strength classes. The classification is shown by a
marking on the screw head. Markings of a higher num-
ber indicate stronger material. For example, a screw
marked 10-9 is stronger than one marked 8-8. For this
reason, it is important when fasteners are dismantled,
that the screws are put back in the correct places
when they are re-installed. If a bolt must be replaced
check in the spare parts catalogue to make sure the
correct type is used.
Sealant
Several types of sealant and locking liquid are used
on the engines. The properties of the sealants differ
as they are intended for different strengths of fasten-
ings, temperature, resistance to oil and other chemi-
cals, and also for different materials and gap thick-
nesses found in the engine.
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 Workshop Manual the user will
find that each section where these agents are applied
in production states which type was used on the en-
gine.
For service work, an similar product from the same
manufacturer, or corresponding product with the same
characteristics from another manufacturer, can be
used.
When using sealants and locking fluids, make sure
that mating surfaces are dry and free from oil, grease,
paint, anti-corrosion agent and old sealant. Always fol-
low the manufacturer’s instructions for use regarding
temperature range, curing time and any other instruc-
tions for the product
Two different basic types of agent are used on the en-
gine. These are:
1. RTV agent (Room Temperature Vulcanizing). Used
for gaskets, sealing gasket joints or coating gaskets.
RTV is visible when a part has been disassembled;
old RTV must be removed before resealing the joint.
The following agents are of RTV-type: Loctite® 574,
Volvo Penta 840879-1, Permatex® No. 3, Volvo Pen-
ta 1161099-5, Permatex® No 77. Old sealant can be
removed using denatured alcohol in all cases.
2. Anaerobic agents. These agents cure in the
absence of air. These agents are used when two solid
components, i.e. cast components, are fitted together
without a gasket. Common uses are also to lock and
seal plugs, stud threads, taps, oil pressure monitors
etc. Hardened anaerobic preparations are glassy and
for this reason, the preparations are colored to make
them visible. Cured anaerobic agents are extremely
resistant to solvents and the old agent cannot be re-
moved. When reinstalling the part, degrease it careful-
ly and then apply new sealant.
The following agents are anaerobic: Loctite® 572
(white), Loctite® 241 (blue).
Notice: Loctite® is a registered trademark for the Loctite Corpo-
ration.
Permatex® is a registered trademark for the Permatex Corpora-
tion.

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