Lock Nuts; Strength Classes; Sealing Compounds Etc.; Safety Regulations For Fluorocarbon Rubber - Volvo Penta D1-13 Workshop Manual

Lock nuts

Removed locknuts may not be re-used; they must be
replaced by new ones, as locking properties are
impaired or lost with re-use.
In the case of lock nuts with plastic inserts the tight-
ening torque indicated must be reduced if the nut has
the same nut height as a standard, all-metal hexag-
onal nut.
Reduce the torque by 25% for bolt sizes of 8 mm or
larger.
In the case of lock nuts with plastic inserts with a high
nut-height (where the all-metal thread is as high as a
standard hexagonal nut), the indicated torque
applies.

Strength classes

Nuts and bolts are subdivided into different strength
classes. The classification is shown by a marking on
the bolt head. Markings of a higher number indicate
stronger material. For example, a bolt marked 10-9 is
stronger than one marked 8-8.
For this reason, it is important that when bolts are
removed they are returned to their original locations
on re-assembly. When replacing bolts check the
applicable Spare parts catalogue to ensure the cor-
rect bolt is used.

Sealing compounds etc.

To ensure service work is correctly carried out it is
important that the correct type of sealants and locking
fluids are used on joints where such are required.
In each service manual section concerned, the seal-
ants used in product manufacture are indicated. The
same sealants, or sealants with equivalent proper-
ties, must be used for maintenance work.
Make sure 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 regarding applicable
temperatures, hardening times and such.
Two basic types of compound are used:
RTV preparations (Room Temperature Vulcaniz-
ing).
Used most often together with gaskets, e.g. sealing
gasket joints, or are brushed on gaskets. RTV seal-
ants are completely visible when the part has been
removed. Old RTV sealant must be removed before
the component is sealed again. Use denatured alco-
hol.
47701798 05-2013 © AB VOLVO PENTA
Anaerobic agents.
These agents cure (harden) in the absence of air.
These preparations are used when two solid compo-
nents, e.g. 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-assembly, it is important to
carefully degrease and wipe dry components first,
before applying new sealant in accordance with the
instructions.
Safety regulations for fluorocarbon
rubber
Fluorocarbon rubber is a common material in sealing
rings for shafts, and in O-rings, for example.
When fluorocarbon rubber is exposed to high tem-
peratures (above 300°C/572°F), hydrofluoric acid
can form. This is highly corrosive. Contact with the
skin can result in severe chemical burns. Splashes in
your eyes can result in chemical wounds. If you
breathe in the fumes, your lungs can be permanently
damaged.
WARNING!
Seals must never be cut with a torch, or be burnt
afterwards in an uncontrolled manner. Risk for
poisonous gases.
WARNING!
Always use chloroprene rubber gloves (gloves for
chemicals handling) and goggles. Handle the
removed seal in the same way as corrosive acid. All
residue, including ash, can be highly corrosive. Never
use compressed air to blow clean.
Put the remains in a plastic container, seal it and
apply a warning label. Wash the gloves under running
water before removing them.
The following seals are most probably made from flu-
orocarbon rubber:
Seal rings for the crankshaft, camshaft, idler shafts.
O-rings, regardless of where they are installed. O-
rings for cylinder liner sealing are almost always
made of fluorocarbon rubber.
Please note that seals which have not been
exposed to high temperature can be handled nor-
mally.
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