Volvo Penta D2-55, Workshop Manual

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7
Repair instructions
Torque-angle tightening
With torque/angle tightening, the fastener is tightened
to the specified torque, and tightening then continues
through a pre-determined angle. Example: for 90°
angle tightening, the fastener 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
properties are impaired or lost when the nut is used
several times. For locknuts with plastic inserts, i.e.
Nylock
®
the tightening-torque given in the table shall be
reduced if the Nylock
®
-nut has the same nut height as
a standard all-metal hex-nut. Reduce the torque by
25% for screw size 8 mm or larger. Where Nylock
®
nuts are higher, i.e. the metallic thread is of the same
height as a standard hexagonal nut, the torque given
in the table apply.
Strength classes
Screws and nuts are sub-divided into different
strength classes. Classification is indicated by
markings on the screw head. A marking with higher
number indicates stronger material. For example, a
screw marked 10-9 is stronger than one marked 8-8.
For this reason, when fasteners are removed, it is
important that the screws are put back in the correct
places when they are re-installed. If a screw must be
replaced, check in the spare parts catalogue to make
sure the correct screw is used.
Sealant
Several different types of sealant and locking fluids
are used on the engine. The properties of the
preparations differ, and they are intended for different
strengths of fastener, temperature, resistance to oil
and other chemicals, and for the different materials
and gap thicknesses found in the engine.
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
required.
In this Service Manual, the user will find that each
section where these agents are applied in production
states which type was used on the engine.
In service work, the same preparations or preparations
of corresponding properties, but of other makes, shall
be used.
When sealants and locking fluids are used, it is
important that the surfaces are free from oil, grease,
paint and rust-protection, and that they are dry.
Always follow the manufacturer’s instructions for use
regarding temperature range, curing time and any oth-
er instructions for the product.
Two different basic types of agent are used on the
engine. These are:
RTV preparations (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 RTV preparations are mentioned in the
workshop manual: Loctite
®
574, Silicone GE
RTV1473W, Permatex ® No. 3, Volvo Penta 1161099-
5, Permatex ® No 77. Old sealant can be removed
using denatured alcohol in all cases.
Anaerobic agents. These agents cure in the absence
of air. These preparations are used when two solid
components, such as two 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. Hardened anaerobic
preparations are highly resistant to solvents, and old
compound can not be removed. On re-installation,
degrease carefully and then apply new sealant.
The following anaerobic preparations are mentioned in
the workshop manual: Loctite
® 572 (white color).
NOTE: Loctite® is a registered trademark belonging to the Loctite
Corporation, Permatex® is a registered trademark belonging to the
Permatex Corporation.