May 2nd 2008
 

Road testing after repair is a vital part of what we do. We don't test after oil changes, but essentially if the  wheels have been
off, it goes out for a trial run and final approval (usually by me). 

I'm sure that most experienced automotive technicians can detect faults in the same way that I do and road testing has a couple
of other advantages, if the tester knows his stuff.

At this time of year, we are very busy, but people will show up at the last moment with a noise in their car that is of concern to them.
Since we cannot possibly find a free lift, the next best solution is a road test.

A bumpy road will show up any looseness in the suspension and depending on the noise, it is very often possible to gauge the
seriousness of the fault. A loose sway bar link sounds terrible but is not really a danger and can be treated as a routine repair.
But a loose ball joint is now or never and has to be fitted into our schedule somehow.

The same principle applies to brake noises. A loud scraping noise usually indicates metal on metal and severe vibration under
braking needs immediate attention also. On the other hand, a little intermittent noise when turning usually indicates a mild amount
of rust build up on the edges of the rotors or drums and a routine cleaning may be all that is required. If the car has alloy wheels, there
is even the possibility of assessing how much life is left in the brakes, because the pads and rotors are easily visible.

Engine noises can be analysed mostly by just blipping the throttle and listening carefully to differentiate between piston slap,
wrist pin looseness, noisy valves and a terminal rapping noise from the main bearings..

Automatic transmissions don't usually make any noise, they just begin to misbehave and a road test is the only way to
analyse this fault.

A second advantage of road testing is that in many cases, where someone wants an inspection on an almost new car,
say one that is two years old and has less than 40,000 Km on the clock, a full wheels up inspection is probably not necessary.
Particularly if the prospective owner cannot wait a week.

A road test over a bumpy road signals any problems with the suspension.
A good hard application of the brakes tells a similar story.

Then an empty parking lot, where noise is at a minimum, is selected, the car is parked with the engine running and the front wheels
cranked over as far as they will go. An under the hood inspection of all fluids, except coolant, and a revving of the engine to detect
noises, is followed by engine shut down to inspect all the belts.

Going down on hands and knees then allows inspection of the CV boots, the exhaust system, the rust condition underneath
and a check for any fluid leaks.

A careful walk around will always show if the car has been repainted.

Tires condition is easily noted. On the way back to the shop, the clutch, air conditioning and electrical functions such as electric
windows can be checked. Wheel alignment can be judged with a smooth road and a "hands off the steering wheel to see what
happens next" approach. All this usually takes about twenty minutes and can only be done on a dry day, preferably with plenty of
sunshine.

Then there is the "seat of the pants factor" which develops in ones mind over many years. In spite of finding nothing immediately
wrong, it's sometimes hard to ignore the warning bell ringing in ones head that says all is not correct.

In which case, even a very late model used car has to go on the lift.

Of course there is also the "CR" factor. If a particular car has a bad reputation, it had better be in first class shape, because an
inherently unreliable vehicle that has been abused is just going to get worse and worse as time goes on.