 |
|
An
engine works hardest when it accelerates...
|
Driving
a new car is fun but, as the car ages, you lose confidence
in its ability to take you on any long trips. This
is not just a psychological phenomenon. Conditions
on a long journey are sufficiently different to a
succession of short trips for a car to protest by
breaking down. You have a vague feeling that the car
needs attention, but do not know how to examine it
systematically.
A
great deal can be learned by driving the car attentively,
listening to the noises, and monitoring the fuel and
oil consumption. An engine works hardest when it accelerates,
so a good test of its condition is to floor the throttle
at about 1 500 r/min in the highest gear. If the engine
pulls smoothly, accelerating slowly at first and later
more strongly, it means that a host of components
are doing their job properly.
But
if the engine jerks soon after you put your foot down,
•
the distributor points or the spark plug gaps may
need adjustment
•
or there could be a crack in the distributor cap,
the body of the
ignition coil, or one of the HT leads;
•
it could be a faulty radio interference suppressor;
these are fitted into the HT leads and get troublesome
due to dirt or old age.
If
there is no jerk, but the car seems to struggle to
accelerate at a particular vehicle speed, and then
recovers, this is known as a flat spot. It is usually
due to an incorrect accelerator pump setting in the
carburettor or even a worn-out, or broken, pump component.
If
the engine pinks, ie makes a tinkling noise during
acceleration, the ignition timing is too far advanced,
or the engine has carboned-up from day-to-day town
driving. In the latter case, an hour or two on a freeway
at 120 km/h will burn most of the carbon away and
the car will be noticeably more lively. If the engine
is just sluggish at all speeds then the ignition timing
is most likely retarded.
If
the engine misfires (seems to run on only some of
the cylinders) take it to a competent mechanic, because
there could be several causes. However, if it's fine
while it idles the fault is not likely to be serious.
|
