Volvo Penta TAD420VE, Workshop Manual

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8
General Information Group 20
Sealant
It is therefore important that bolts removed during the
disassembly of a bolted joint must be reinstalled in
their original position when assembling the joint. When
replacing a bolt, check in the spare parts catalogue to
make sure the correct bolt is used.
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 as
described in the Workshop Manual or the Service Bul-
letin.
During service operations use the same agent or an
alternative.
Make sure that mating surfaces are dry and free from
oil, grease, paint and anticorrosion agent before apply-
ing sealant or locking fluid.
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:
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.
Old sealant can be removed using methylated spirits
in all cases.
Anaerobic agents:
These agents cure in an absence of air. They are use-
d 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, petcocks, oil pressure switches, and so on.
The cured material is glass like and it is therefore co-
lored to make it visible. Cured anaerobic agents are
extremely resistant to solvents and the old agent can-
not be removed. When reinstalling the part is carefully
degreased and then new sealant is applied.
Safety rules for fluorocarbon
rubber
Fluorocarbon rubber is a common material in seal
rings for shafts, and in O-rings.
When fluorocarbon rubber is subjected to high tempe-
ratures (above 300°C or 572°F),
hydrofluoric acid can
be formed, which is highly corrosive.
Skin contact can give severe chemical burns. Splas-
hes in eyes can give severe chemical burns.
Breathing of fumes can be permanently damaged
lungs.
WARNING! Be very careful when working on
engines that have been exposed to high tempe-
ratures, e.g. overheating during a seizure or fire.
Seals must never be cut with an oxy-acetylene
torch, or be burned up afterwards in an uncon-
trolled manner.
Always use gloves made of chloroprene rubber
(gloves for handling chemicals) and protective
goggles.
Handle the removed material like corrosive acid.
All residues, including ash, can be highly corro-
sive.
Never use compressed air to blow anything clean.
Put the remains in a plastic box which is sealed
and provided with a warning label. Wash the glov-
es under running water before removing them.
These following seals are probably made out of fluoro-
carbon rubber:
Seal rings for crankshaft, camshaft, and interme-
diate shafts.
O-rings irrespective of where they are installed.
O-rings for cylinder liner sealing are usually made
out of fluorocarbon rubber.