1986 BMW 3 SERIES tach not working

the stop-light switch (see Section 13). Note:
On right-hand-drive models, the brake pedal
in on the right-hand side of the vehicle, and is
connected to the left-hand side by a cross-
shaft. The adjustment is carried out on the
pushrod at the left-hand side, but the
dimension is measured at the pedal on the
right-hand side.
14On 5-Series models, adjust the brake
pedal height and the stop-light switch (see
Section 13).
15Refit the master cylinder (see Section 7)
and attach the vacuum hose.
16Carefully test the operation of the brakes
before returning the vehicle to normal use
9 Hydraulic brake servo-
description, removal and
refitting
3
Warning: Brake fluid is
poisonous. It is also an effective
paint stripper. Refer to the
warning at the start of Section 16.
Description
1On 5-Series E28 (“old-shape”) models, a
hydraulic brake servo system is fitted. The
servo unit, located between the brake pedal
(left-hand-drive) or cross-shaft lever (right-
hand-drive) and the master cylinder, is
operated by hydraulic pressure generated by
the power steering pump. When the engine is
running, the power steering pump supplies
hydraulic pressure to a power flow regulator/
accumulator. The regulator/accumulator
stores and regulates the pressure to the
hydraulic brake servo. When you press the
brake pedal, the pressure in the servo helps
actuate the master cylinder, reducing pedal
effort.
2The hydraulic brake servo cannot be
overhauled; if it fails, a new one must be fitted.
Testing the system requires special tools, so
even fault diagnosis is beyond the scope of
the home mechanic. If the system fails, take it
to a dealer service department or other
qualified garage for repairs.
Removal and refitting
3With the engine off, discharge the hydraulic
accumulator by depressing the brake pedal
20 times or more.
4Remove the master cylinder (see Section 7).
5Clean the area around the return and
supply line fittings, then disconnect them.
Plug the lines, to prevent dirt from entering the
system, and to prevent further fluid loss.
Caution: Even a particle of dirt
can damage the servo, so be
extremely careful to prevent dirt
from entering the system while
the lines are disconnected.
6Working from inside the passenger
compartment, remove the lower left trim
panels above the brake pedal (left-hand-drive
models) or glovebox and trim (right-hand-drive models). On left-hand-drive models, also
disconnect the pedal return spring.
7Prise off the retaining clip, and disconnect
the pushrod from the brake pedal (see
illustration 8.9) or cross-shaft lever.
8Remove the four mounting nuts and
remove the brake servo (see illus-
tration 8.10).
9Refitting is the reverse of removal. Tighten
the hydraulic lines to the torque listed in this
Chapter’s Specifications. Note:Don’t try to
tighten these fittings without a torque wrench.
If they’re loose, they can leak, which can affect
system operation; if they’re tight, they can be
damaged, and they’ll also leak. You’ll need a
crowfoot-type split ring (“brake”) attachment
for your torque wrench to tighten the fittings
properly.
10When you’re done, bleed the brake
hydraulic system (Section 16) and adjust the
brake pedal travel and the stop-light switch
(see Section 13).
10 Handbrake cable(s)- renewal
2
1Peel back the boot at the base of the
handbrake lever, and remove the handbrake
cable adjusting nut (see illustration)which
also secures the cable to the handbrake lever.There are two cables - one for each rear wheel
- and a nut for each cable. On some models, it
may be necessary to remove the centre
console completely for access.
2Raise the vehicle and support it securely on
axle stands.
3Remove the rear brake drum (see Section 6)
or rear brake disc (see Section 5).
4On rear drum models, unhook the
handbrake cable from the lever on the rear
brake shoe (see Section 6). On rear disc
models, remove the handbrake shoes and the
actuator (see Section 12) and unhook the
handbrake cable from the actuator (see
illustrations).
5On rear drum models, pull the cable and
cable conduit (tube) out of the back of the
brake backplate, then detach the cable
conduit from the cable clips on the back of
the trailing arm (it’s easier to pull out the old
cable, and fit the new cable, with the conduit
straight instead of curved). On rear disc
models, it’s unnecessary to detach the cable
conduit from the brake backplate, but it’s a
good idea to detach the conduit from the clips
and guides securing it to the trailing arm, to
take some of the bend out of the conduit.
6Working from the wheel end of the cable
conduit, pull the cable out of the conduit (see
illustration).
7Lubricate the new cable with multi-purpose
grease, then insert it into the cable conduit
Braking system 9•11
10.1 Peel back the handbrake lever boot
and remove the relevant handbrake cable
adjusting nut (both arrowed)
10.6 Pull the cable out of its conduit;
before you refit the new cable, be sure to
lubricate it with multi-purpose grease10.4b . . . then remove the pin securing the
cable to the inner cam, and remove the
inner cam
10.4a To detach the handbrake cable from
the handbrake actuator on models with rear
disc brakes, pull on the outer cam and
disconnect it from the inner cam . . .
9

4On some models, working inside the boot,
you can remove the trim to access the upper
mounting nuts; on later models, you’ll have to
remove the rear seat back to get at the upper
mounting nuts. On Touring (Estate) models,
remove the side backrest and rear seat belt
reels, and unscrew the centring shell on the
wheel arch. On Convertibles, simply remove
the top from the recessed well behind the
passenger compartment, and remove the
small rubber access cover. As you remove the
mounting nuts (see illustration), have an
assistant support the shock absorber from
below so it doesn’t fall out.
5Look for oil leaking past the seal in the top
of the shock absorber body. Inspect the
rubber bushings in the shock absorber eye. If
they’re cracked, dried or torn, renew them. To
test the shock absorber, grasp the shock
absorber body firmly with one hand, and push
the damper rod in and out with the other. The
strokes should be smooth and firm. If the rod
goes in and out too easily, or unevenly, the
shock absorber is defective and must be
renewed.
Refitting
6Fit the shock absorbers in the reverse order
of removal, but don’t tighten the mounting
bolts and nuts yet.
7Bounce the rear of the vehicle a couple of
times to settle the bushings, then tighten the
nuts and bolts to the torque values listed in
this Chapter’s Specifications.
10 Rear coil springs (3-Series)-
removal and refitting
4
Note: Although coil springs don’t always wear
out simultaneously, renew both left and right
springs at the same time, to prevent handling
peculiarities or abnormal ride quality.
Removal
1Loosen the wheel bolts. Chock the front
wheels, then raise the rear of the vehicle andsupport it securely on axle stands. Make sure
the stands don’t interfere with the rear
suspension when it’s lowered and raised
during this procedure. Remove the wheels.
2Disconnect the mountings and brackets
which support the rear portion of the exhaust
system, and temporarily lower the exhaust
system (see Chapter 4). Lower the exhaust
system only enough to lower the suspension
and remove the springs. Suspend the exhaust
with a piece of wire.
3Support the differential with a trolley jack,
then remove the differential rear mounting
bolt. Push the differential down, and wedge it
into this lowered position with a block of
wood. This reduces the drive angle,
preventing damage to the CV joints when the
trailing arms are lowered to remove the
springs.
4Place a trolley jack under the trailing arm.
5If the vehicle has a rear anti-roll bar,
disconnect the bar from its connecting links,
or disconnect the links from the trailing arms
(see Section 12).
6Loop a chain through the coil spring, and
bolt the chain together, to prevent the coil
spring from popping out when the trailing arm
is lowered. Be sure to leave enough slack in
the chain to allow the spring to extend
completely.
7Disconnect the shock absorber lower
mounting bolt (see Section 9), carefully lower
the trailing arm and remove the coil spring.
Refitting
8Refitting is the reverse of removal. As the
trailing arm is raised back up, make sure the
spring seats properly.
11 Rear shock absorber/coil
spring assembly (5-Series)-
removal and refitting
4
Removal
Note:Although shock absorbers don’t always
wear out simultaneously, renew both left and
right shock absorbers at the same time, to
prevent handling peculiarities or abnormal ride
quality.1Loosen the wheel bolts, then chock the
front wheels. Raise the vehicle and support it
securely on axle stands. Remove the wheels.
2Remove the shock absorber lower
mounting bolt (see illustration).
3On early models, peel back the trim inside
the luggage compartment far enough to
access the upper mounting nuts. To get at the
upper mounting nuts on later models, first
remove the rear seat cushion (see Chap-
ter 11), then remove the two bolts holding the
rear seat backrest, and remove the backrest.
Support the trailing arm with a jack, and
remove the upper mounting nuts (see
illustration). Lower the jack, and remove the
shock absorber and the gasket. To separate
the shock absorber and spring, refer to
Section 6.
Refitting
4Refitting is the reverse of removal. Don’t
forget to fit the gasket between the upper end
of the shock absorber and the body. Tighten
the upper nuts to the torque listed in this
Chapter’s Specifications. Don’t tighten the
lower bolt until the vehicle is lowered.
5Lower the vehicle, and with it sitting at the
normal ride height, tighten the lower bolt to
the torque listed in this Chapter’s Specifi-
cations.
12 Rear anti-roll bar-
removal and refitting
2
Removal
Note:The rear anti-roll bar is mounted
basically the same way on all models. Follow
these general removal and refitting
procedures, keeping in mind any variations.
1Chock the front wheels, then raise the rear
of the vehicle and support it securely on axle
stands.
2Remove the anti-roll bar bracket bolts or
nuts (see illustration).
3Disconnect the anti-roll bar from the link at
each end of the bar (see illustrations)and
detach the anti-roll bar.
Suspension and steering systems 10•9
11.3 Shock absorber upper mounting nuts
(arrowed) on a later (E34) 5-Series model11.2 Remove the shock absorber lower
mounting bolt (arrowed)9.4 Shock absorber upper mounting nuts
(arrowed) - late-model convertible shown.
On other early models, upper nuts are
accessible from the luggage compartment;
on later models, they’re behind the back of
the rear seat, up under the parcel shelf
10

the longer side of the sleeve facing towards
the centre of the vehicle.
Refitting
12Refitting is the reverse of removal. Refit
the inner pivot bolt first. Don’t fully tighten the
nuts on the pivot bolts or the shock absorber
yet.
13Bleed the brakes as described in Chap-
ter 9.
14Support the trailing arm with a trolley jack,
and raise it to simulate normal ride height.
Tighten the bolts and nuts to the torques
listed in this Chapter’s Specifications.
15 Rear wheel bearings-
renewal
4
3-Series models
1Loosen the driveshaft nut and the rear
wheel bolts, then chock the front wheels.
Raise the rear of the vehicle and place it
securely on axle stands. Remove the rear
wheel. Note: Depending on the type of rear
wheel, it may be necessary to remove the
wheel first, remove the hubcap, then refit the
wheel and loosen the driveshaft nut.
2Remove the driveshaft (see Chapter 8).3On models with rear brake drums, remove
the drum. On models with rear disc brakes,
remove the brake caliper and mounting
bracket. Don’t disconnect the hose. Hang the
caliper out of the way with a piece of wire.
Remove the brake disc (see Chapter 9).
Working from behind, drive the wheel hub out
of the wheel bearing with a large socket or a
piece of pipe.
4Remove the large circlip (see illustration)
that holds the wheel bearing in the wheel
bearing housing, then drive out the bearing
with a large socket or piece of pipe.
5Refitting is basically the reverse of removal,
bearing in mind the following points:
a) Be extremely careful where you place the
socket or piece of pipe when you drive
the new bearing into the housing. It
should be butted up against the outer
race of the bearing. Driving in the new
bearing using the inner race will ruin the
bearing.
b) Refit the wheel and lower the vehicle to
the ground before attempting to tighten
the driveshaft nut to the torque listed in
the Chapter 8 Specifications.
5-Series models
6Chock the front wheels, then raise the rear
of the vehicle and support it securely on axle
stands. Disconnect the outer CV joint from the
drive flange (see Chapter 8). Support the outer
end of the driveshaft with a piece of wire -
don’t let it hang, as this could damage the
inner CV joint.
7Prise out the lockplate that secures the
drive flange nut (see illustration). Once
you’ve prised out an edge of the lockplate,
pull it out with a pair of needle-nose pliers.
8Lower the vehicle and unscrew the drive
flange nut, but don’t remove it yet. You’ll need
a long bar (see illustration).
Warning: Don’t attempt to loosen
this nut with the vehicle on axle
stands. The force required to
loosen the nut could topple the
vehicle from the stands.
9Loosen the rear wheel bolts, raise the rear
of the vehicle again, place it securely on axle
stands and remove the wheel.
10Remove the brake caliper and the brake
disc (see Chapter 9). Hang the caliper out of
the way with a piece of wire.
11Remove the drive flange nut. Using a
suitable puller, remove the drive flange (see
illustration).
12Using a soft-faced hammer, drive the stub
axle out of the bearing (see illustration). If the
bearing inner race comes off with the stub
Suspension and steering systems 10•11
15.7 Prise out the lockplate that secures
the drive flange nut - once you’ve prised
out an edge of the lockplate, pull it out
with a pair of needle-nose pliers15.4 An exploded view of the 3-Series rear
wheel bearing assembly14.8 On 1983 and later models, remove
one of these trailing arm-to-axle carrier
bolts (it doesn’t matter which one you
remove - one attaches the link to the
trailing arm, and the other attaches the link
to the axle carrier)
15.12 Using a soft-faced hammer, drive
the stub axle out of the bearing15.11 Remove the drive flange with a
puller15.8 Lower the vehicle and loosen the
drive flange nut
10
If the bearing inner race
sticks to the hub (it probably
will), use a puller to remove
the race from the hub.

it to the approximate size and shape required,
then pull off the backing paper (if used) and
stick the tape over the hole; it can be
overlapped if the thickness of one piece is
insufficient. Burnish down the edges of the
tape with the handle of a screwdriver or
similar, to ensure that the tape is securely
attached to the metal underneath.
Bodywork repairs - filling and
respraying
Before using this Section, see the Sections
on dent, deep scratch, rust holes and gash
repairs.
Many types of bodyfiller are available, but
generally speaking, those proprietary kits
which contain a tin of filler paste and a tube of
resin hardener are best for this type of repair. A
wide, flexible plastic or nylon applicator will be
found invaluable for imparting a smooth and
well-contoured finish to the surface of the filler.
Mix up a little filler on a clean piece of card
or board - measure the hardener carefully
(follow the maker’s instructions on the pack),
otherwise the filler will set too rapidly or too
slowly. Using the applicator, apply the filler
paste to the prepared area; draw the
applicator across the surface of the filler to
achieve the correct contour and to level the
surface. As soon as a contour that
approximates to the correct one is achieved,
stop working the paste - if you carry on too
long, the paste will become sticky and begin
to “pick-up” on the applicator. Continue to
add thin layers of filler paste at 20-minute
intervals, until the level of the filler is just
proud of the surrounding bodywork.
Once the filler has hardened, the excess
can be removed using a metal plane or file.
From then on, progressively-finer grades of
abrasive paper should be used, starting with a
40-grade production paper, and finishing with
a 400-grade wet-and-dry paper. Always wrap
the abrasive paper around a flat rubber, cork,
or wooden block - otherwise the surface of
the filler will not be completely flat. During the
smoothing of the filler surface, the wet-and-
dry paper should be periodically rinsed in
water. This will ensure that a very smooth
finish is imparted to the filler at the final stage.
At this stage, the “dent” should be
surrounded by a ring of bare metal, which in
turn should be encircled by the finely
“feathered” edge of the good paintwork.
Rinse the repair area with clean water, until all
of the dust produced by the rubbing-down
operation has gone.
Spray the whole area with a light coat of
primer - this will show up any imperfections in
the surface of the filler. Repair these
imperfections with fresh filler paste or
bodystopper, and once more smooth the
surface with abrasive paper. Repeat this
spray-and-repair procedure until you are
satisfied that the surface of the filler, and the
feathered edge of the paintwork, are perfect.
Clean the repair area with clean water, and
allow to dry fully.The repair area is now ready for final
spraying. Paint spraying must be carried out
in a warm, dry, windless and dust-free
atmosphere. This condition can be created
artificially if you have access to a large indoor
working area, but if you are forced to work in
the open, you will have to pick your day very
carefully. If you are working indoors, dousing
the floor in the work area with water will help
to settle the dust which would otherwise be in
the atmosphere. If the repair area is confined
to one body panel, mask off the surrounding
panels; this will help to minimise the effects of
a slight mis-match in paint colours. Bodywork
fittings (eg chrome strips, door handles etc)
will also need to be masked off. Use genuine
masking tape, and several thicknesses of
newspaper, for the masking operations.
Before commencing to spray, agitate the
aerosol can thoroughly, then spray a test area
(an old tin, or similar) until the technique is
mastered. Cover the repair area with a thick
coat of primer; the thickness should be built
up using several thin layers of paint, rather
than one thick one. Using 400-grade wet-and-
dry paper, rub down the surface of the primer
until it is really smooth. While doing this, the
work area should be thoroughly doused with
water, and the wet-and-dry paper periodically
rinsed in water. Allow to dry before spraying
on more paint.
Spray on the top coat, again building up the
thickness by using several thin layers of paint.
Start spraying at one edge of the repair area,
and then, using a side-to-side motion, work
until the whole repair area and about 2 inches
of the surrounding original paintwork is
covered. Remove all masking material 10 to
15 minutes after spraying on the final coat of
paint.
Allow the new paint at least two weeks to
harden, then, using a paintwork renovator, or
a very fine cutting paste, blend the edges of
the paint into the existing paintwork. Finally,
apply wax polish.
Plastic components
With the use of more and more plastic body
components by the vehicle manufacturers (eg
bumpers. spoilers, and in some cases major
body panels), rectification of more serious
damage to such items has become a matter
of either entrusting repair work to a specialist
in this field, or renewing complete
components. Repair of such damage by the
DIY owner is not really feasible, owing to the
cost of the equipment and materials required
for effecting such repairs. The basic technique
involves making a groove along the line of the
crack in the plastic, using a rotary burr in a
power drill. The damaged part is then weldedback together, using a hot-air gun to heat up
and fuse a plastic filler rod into the groove.
Any excess plastic is then removed, and the
area rubbed down to a smooth finish. It is
important that a filler rod of the correct plastic
is used, as body components can be made of
a variety of different types (eg polycarbonate,
ABS, polypropylene).
Damage of a less serious nature (abrasions,
minor cracks etc) can be repaired by the DIY
owner using a two-part epoxy filler repair
material. Once mixed in equal proportions,
this is used in similar fashion to the bodywork
filler used on metal panels. The filler is usually
cured in twenty to thirty minutes, ready for
sanding and painting.
If the owner is renewing a complete
component himself, or if he has repaired it
with epoxy filler, he will be left with the
problem of finding a suitable paint for finishing
which is compatible with the type of plastic
used. At one time, the use of a universal paint
was not possible, owing to the complex range
of plastics encountered in body component
applications. Standard paints, generally
speaking, will not bond to plastic or rubber
satisfactorily. However, it is now possible to
obtain a plastic body parts finishing kit which
consists of a pre-primer treatment, a primer
and coloured top coat. Full instructions are
normally supplied with a kit, but basically, the
method of use is to first apply the pre-primer
to the component concerned, and allow it to
dry for up to 30 minutes. Then the primer is
applied, and left to dry for about an hour
before finally applying the special-coloured
top coat. The result is a correctly-coloured
component, where the paint will flex with the
plastic or rubber, a property that standard
paint does not normally possess.
6 Bodywork repair-
major damage
5
1Major damage must be repaired by a
qualified bodywork repair specialist, or
preferably by a BMW dealer. Specialised
equipment is required to do the job properly.
2If the damage is extensive, the bodyshell
must be checked for proper alignment, or the
vehicle’s handling characteristics may be
adversely affected and other components
may wear at an accelerated rate.
3Due to the fact that all of the major body
components (bonnet, wings, etc.) are
separate units, any seriously damaged
components should be replaced with new
ones rather than repaired.
Bodywork and fittings 11•3
11
If bodystopper is used, it can
be mixed with cellulose
thinners to form a really thin
paste which is ideal for filling
small holes
Sometimes bodywork
components can be found in
a scrapyard that specialises
in used vehicle components,
often at a considerable saving over the
cost of new parts.

REF•18Automotive chemicals and lubricants
A number of automotive chemicals and
lubricants are available for use during vehicle
maintenance and repair. They include a wide
variety of products ranging from cleaning
solvents and degreasers to lubricants and
protective sprays for rubber, plastic and
vinyl.
Cleaners
Carburettor cleaner and choke cleaner
is a strong solvent for gum, varnish and
carbon. Most carburettor cleaners leave a
dry-type lubricant film which will not harden or
gum up. Because of this film, it is not
recommended for use on electrical
components.
Brake system cleaneris used to remove
grease and brake fluid from the brake system,
where clean surfaces are absolutely
necessary. It leaves no residue, and often
eliminates brake squeal caused by
contaminants.
Electrical cleaner removes oxidation,
corrosion and carbon deposits from electrical
contacts, restoring full current flow. It can also
be used to clean spark plugs, carburettor jets,
voltage regulators and other parts where an
oil-free surface is desired.
Moisture dispersantsremove water and
moisture from electrical components such as
alternators, voltage regulators, electrical
connectors and fuse blocks. They are non-
conductive and non-corrosive.
Degreasersare heavy-duty solvents used
to remove grease from the outside of the
engine and from chassis components. They
can be sprayed or brushed on, and are usually
rinsed off with water.
Lubricants
Engine oilis the lubricant formulated for
use in engines. It normally contains a wide
variety of additives to prevent corrosion and
reduce foaming and wear. Engine oil comes in
various weights (viscosity ratings) from 5 to
60. The recommended weight of the oil
depends on the season, temperature and the
demands on the engine. Light oil is used in
cold climates and under light load conditions.
Heavy oil is used in hot climates, and where
high loads are encountered. Multi-viscosity
(multigrade) oils are designed to have
characteristics of both light and heavy oils,
and are available in a number of weights from
5W-20 to 20W-50.
Gear oilis designed to be used in
differentials, manual transmissions and other
areas where high-temperature lubrication is
required.
Chassis and wheel bearing greaseis a
heavy grease used where increased loads and
friction are encountered, such as for wheel
bearings, balljoints, tie-rod ends and universal
joints.High-temperature wheel bearing grease
is designed to withstand the extreme
temperatures encountered by wheel bearings
in disc brake-equipped vehicles. It usually
contains molybdenum disulphide (moly),
which is a dry-type lubricant.
White greaseis a heavy grease for metal-
to-metal applications where water is a
problem. White grease stays soft at both low
and high temperatures, and will not wash off
or dilute in the presence of water.
Assembly lubeis a special extreme-
pressure lubricant, usually containing moly,
used to lubricate high-load parts (such as
main and rod bearings and cam lobes) for
initial start-up of a new engine. The assembly
lube lubricates the parts without being
squeezed out or washed away until the engine
oiling system begins to function.
Silicone lubricants are used to protect
rubber, plastic, vinyl and nylon parts.
Graphite lubricantsare used where oils
cannot be used due to contamination
problems, such as in locks. The dry graphite
will lubricate metal parts while remaining
uncontaminated by dirt, water, oil or acids. It
is electrically conductive, and will not foul
electrical contacts in locks such as the
ignition switch.
Penetrating oilsloosen and lubricate
frozen, rusted and corroded fasteners and
prevent future rusting or freezing.
Heat-sink greaseis a special electrically
non-conductive grease that is used for
mounting electronic ignition modules where it
is essential that heat is transferred away from
the module.
Sealants
RTV sealantis one of the most widely-
used gasket compounds. Made from silicone,
RTV is air-curing; it seals, bonds, waterproofs,
fills surface irregularities, remains flexible,
doesn’t shrink, is relatively easy to remove,
and is used as a supplementary sealer with
almost all low- and medium-temperature
gaskets.
Anaerobic sealantis much like RTV in that
it can be used either to seal gaskets or to form
gaskets by itself. It remains flexible, is solvent-
resistant, and fills surface imperfections. The
difference between an anaerobic sealant and
an RTV-type sealant is in the curing. RTV
cures when exposed to air, while an anaerobic
sealant cures only in the absence of air. This
means that an anaerobic sealant cures only
after the assembly of parts, sealing them
together.
Thread and pipe sealant is used for
sealing hydraulic and pneumatic fittings and
vacuum lines. It is usually made from a Teflon
compound, and comes in a spray, a paint-on
liquid and as a wrap-around tape.
Chemicals
Anti-seize compoundprevents seizing,
chafing, cold welding, rust and corrosion in
fasteners. High-temperature anti-seize,
usually made with copper and graphite
lubricants, is used for exhaust system and
exhaust manifold bolts.
Anaerobic locking compoundsare used
to keep fasteners from vibrating or working
loose, and cure only after installation, in the
absence of air. Medium-strength locking
compound is used for small nuts, bolts and
screws that may be removed later. High-
strength locking compound is for large nuts,
bolts and studs which aren’t removed on a
regular basis.
Oil additivesrange from viscosity index
improvers to chemical treatments that claim
to reduce internal engine friction. It should be
noted that most oil manufacturers caution
against using additives with their oils.
Fuel additivesperform several functions,
depending on their chemical make-up. They
usually contain solvents that help dissolve
gum and varnish that build up on carburettor,
fuel injection and intake parts. They also serve
to break down carbon deposits that form on
the inside surfaces of the combustion
chambers. Some additives contain upper
cylinder lubricants for valves and piston rings,
and others contain chemicals to remove
condensation from the fuel tank.
Miscellaneous
Brake fluidis specially-formulated
hydraulic fluid that can withstand the heat and
pressure encountered in brake systems. It is
poisonous and inflammable. Care must be
taken so this fluid does not come in contact
with painted surfaces or plastics. An opened
container should always be resealed, to
prevent contamination by water or dirt. Brake
fluid absorbs moisture from the air, if left in an
unsealed container.
Weatherstrip adhesiveis used to bond
weatherstripping around doors, windows and
boot lids. It is sometimes used to attach trim
pieces.
Undersealis a petroleum-based, tar-like
substance that is designed to protect metal
surfaces on the underside of the vehicle from
corrosion. It also acts as a sound-deadening
agent by insulating the bottom of the vehicle.
Waxes and polishesare used to help
protect painted and plated surfaces from the
weather. Different types of paint may require
the use of different types of wax and polish.
Some polishes utilise a chemical or abrasive
cleaner to help remove the top layer of
oxidised (dull) paint on older vehicles. In
recent years, many non-wax polishes
containing a wide variety of chemicals such as
polymers and silicones have been introduced.
These non-wax polishes are usually easier to
apply, and last longer than conventional
waxes and polishes.