77PANEL REPAIRS
10
SEALING AND CORROSION PROTECTION Underbody Protection Repairs
When body repairs are carried out, always ensure that
full sealing and corrosion protection treatments are
restored. This applies both to the damaged area, and
also to areas where protection has been indirectly
impaired as a result of accident damage or repair
operations.
Prior to straightening out or panel beating, remove all
corrosion protection material in the damaged area.
This applies in particular to panels coated with wax,
PVC underbody sealer, sound deadening pads etc.
WARNING: DO NOT use oxy-acetylene gas
equipment to remove corrosion prevention
materials. Large amounts of fumes and
gases are liberated by these materials when they
burn.
Equipment for the removal of tough anti-corrosion
sealers offers varying degrees of speed and
effectiveness. The compressed air-operated scraper
(NOT an air chisel) offers a relatively quiet mechanical
method of removal using an extremely rapid
reciprocating action. During use, direct the operating
end of the tool along the work surface.
The most common method is by the use of a hot air
blower with integral scraper.
CAUTION: High temperatures can be
generated with this equipment which may
cause fumes. Always exercise care in its
use.
Another tool, and one of the most efficient methods, is
the rapid-cutting’hot knife’. This tool uses a wide
blade and is quick and versatile, able to be used
easily in profiled sections where access is otherwise
awkward.
Use the following procedure when repairing
underbody coatings:
1.Remove existing underbody coatings.2.After panel repair, clean the affected area with a
solvent wipe, and treat bare metal with an etch
phosphate material.
3.Re-prime the affected area.DO NOT under any
circumstances apply underbody sealer
directly to bare metal surfaces.
4.Replace all heat-fusible plugs which have been
disturbed. Use rubber grommets of equivalent
size if plugs are not available, but ensure that
they are embedded in sealer.
5.Mask off all mounting faces from which
mechanical components, hoses and pipe clips,
have been removed. Underbody sealer must be
appliedbeforesuch components are refitted.
6.Brush sealer into all exposed seams.
7.Spray the affected area with an approved
service underbody sealer.
8.Remove masking from component mating faces,
and touch-in where necessary. Allow adequate
drying time before applying underbody wax.
Underbody Wax
After refitting mechanical components, including
hoses, pipes and small fixtures, mask off the brake
discs and apply a coat of approved underbody wax.
NOTE: Where repairs include the
application of finish paint coats in the
areas requiring underbody wax, paint
operations must be carried out BEFORE wax
application.
Underbonnet Wax
Where repairs have involved replacement of engine
bay panels, treat the entire engine compartment
including all components, clips and small fixtures with
an approved underbonnet lacquer or wax.
Proprietary Anti-Corrosion Treatments
The application of proprietary anti-corrosion
treatments in addition to the factory-applied treatment
could invalidate the Corrosion Warranty and should be
discouraged. This does not apply to approved,
compatible, preservative waxes which may be applied
on top of existing coatings.
ProCarManuals.com
