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WHEN THE
ENGINE STOPS
There you are
bowling along on a nice sunny day (?) when suddenly
the Austin’s engine cuts out or begins to
stutter and whatever and then cuts out. Usually
this happens in the thick of traffic or in some
remote spot and where ever it happens it is a minor
disaster and it can happen to the best maintained
vehicle. So what is the cause of this lack of
forward motion?
One possibility
is simply water or filth in the petrol which has
got through the filter at the fuel pump and has
landed up in the carburettor bowl. There it can
clop the tiny jets found in the bottom of the float
chamber. These can be easily removed and carefully
blown through before replacing. Other causes of
fuel problems can be more serious such as failure
of the fuel pump itself. The diaphragm inside which
makes the suck and blow, can fail as can the two
valves, but this is not a common problem.
Nevertheless, I carry a spare pump in the 1001 box
of bits in my car. Sometimes the fuel has run out
altogether because the fuel gauge is telling big
lies – I have had that happen to me as well
– so spare petrol is carried as
well.
The next and most
common area of sudden failure is in the electrical
system, most notably the ignition system. Now this
problem area strikes at modern cars as well, and
when their ECU’S (electrical control unit)
fails, the vehicle in question has to go home on a
lowloader because the fault is terminal (and
expensive). The same total failure can afflict the
Austin, but in this case the remedy is not only
cheap, but fixable by the roadside. Starting with
the distributor, sometimes the ignition points can
close up with wear (readjust) or they can be burned
and pitted. This latter condition is caused by a
failing condenser and if spotted before breakdown
day, a new condenser and set of points can be
fitted thus avoiding trouble. However, the
condenser can fail without any warning other than
for the engine to begin the spluttering and
wheezing that often precedes the actual running out
of petrol or a carburation problem. This problem is
terminal as far as forward motion is concerned, but
the fitting of a new condenser (which you will now
be carrying in the 1001 box) cures the trouble and
happy days are here again. Condensers are strange
little creatures made out of thin metal foil and
old age plus damp puts them to sleep in the end.
The points by the way, switch on and off the low
voltage current that runs back into the coil and is
converted to high voltage and then fires off at the
appropriate spark plug.
Moving on to the
coil, this is the equivalent of the modern ECU
because when it fails it does so without early
warning and fails totally. When this happens, the
car is disabled and replacing the coil ends the
problem (cost about 10 pounds). The failure is
often as not the high tension windings where an
internal short circuit has developed. Coils are
made up from thousands of turns of fine copper wire
would around a core and eventually, the insulation
between the windings breaks down and so does the
coil. These things can work OK for decades until
one day they don’t, as happened to me on the
April 1st Run. On this occasion a 23 year old coil
had failed so I fitted the spare 67 year old one I
was carrying and away we went. But I now have a new
coil in the 1001 box – just in
case.
Whilst on the
subject of electrics, it is advisable to renew all
the ignition leads and the HT and LT coil wiring at
intervals of 5 years of so. You’d be surprised
how this wiring deteriorates gradually and dodgy
plug leads can cause misfiring and reduced
efficiency. Wire is very cheap and you can use
Lucas Hyperlon (60p a foot) for plug and coil
leads. It is copper cored (don’t use anything
else but copper core wire) and has a soft black
rubbery insulation which looks very period. Make
sure that all the terminals are clean and bright
including the rotor in the distributor (which has
also been known to fail) and install the new
wiring. These days suppressors don’t seem to
be needed on our cars and this is just as well as
they can set up a resistance in the circuit when
they get knackered by time.
And what about
magnetos you may ask? Well the points about wiring
apply to them, but magnetos can also suffer from
total stoppages due to internal shorting and wires
coming adrift. There are also points to be kept in
order. As these devised (which are excellent when
in good health) need an exposition of their own and
as I haven’t dealt with one of them lately,
this needs to be a matter for another
article.
In conclusion you
might be interested to learn that in the
1930’s when coil ignition had replaced the
magnetos, heavy goods vehicles of the day sometimes
had both systems with two plus per cylinder. I used
to run a 1936 Leyland-Metz fire appliance for the
Enfield & District Veteran Vehicle Society and
this machine, being an emergency vehicle, had dual
ignition as a fail safe. I usually ran on the
magneto and started on coil and magneto together.
Running on both did not produce that much more
power from the 8.8 liter petrol engine!
TONY
ELDRIDGE
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