Special car care in the dry season

There's always been plenty of advice on the special conditions and precautions of motoring in "the rainy season". There's much less information – but no less need -  for precautions in the so-called "dry season".

But if we recognize that "dry" also means "dusty", there is a full set of damages and dangers to think about.  To put that in perspective, a vehicle used in very dusty conditions needs to be serviced at least twice as often as a vehicle in wet conditions!

Unless it is actually raining, all roads are dusty.  Always.  Even the tarmac ones.   For dust is not only tiny particles of earth; it is any material in a finely powdered form, reduced to small enough peices that they can be blown about.  Tarmac roads are constantly covered in this road "grime" - particles of rubber wearing from tyres, powder worn from brake pads, drips of engine oil, soot from exhaust pipes, and all the other airmail dirt from sawdust and iron filings to lawn-mowings and carpet fluff.

Some of it you can see, some of it you can't, but  all of it has an effect on your car - in six main ways.

AIR FILTER:  car engines ingest huge volumes of air, and if it is not properly filtered the particles of dirt pollute the air:fuel mixture and reduce combustion efficiency,  they degrade lubricating oil, they clog carburettor jets, and larger particles increase engine wear by acting like sandpaper inside the engine.

While filters must stop the dirt, they must allow free passage of clean air or the engine will run too rich, reducing power, increasing fuel consumption and increasing wear - the rich fuel mixture dissolves the film of lubrication on the cylinder walls.

These factors are serious all the time, but obviously are most crucial in thoroughly "dusty" conditions.   Filters need to be cleaned and replaced even if you motor entirely on tarmac, and  much more often if you motor on unmetalled roads.

The most common type of filter is a "paper element".  The effective life of these components can sometimes be extended, slightly, by blowing dust out of the fibres with a gentle stream of air and very (very!) gentle tapping.   But they should never be cleaned with a direct blast of high-pressure air or tapped vigorously.  These actions tear the microscopic fibres, and even if the paper looks cleaner it will then allow larger particles of dirt through and no longer do its job properly.

The blow-clean technique is to place the filter on clean ground (eg concrete) and blow high pressure air onto the ground in the middle of the element – do not blow the air at the element itself.

Do not underestimate the damage that can be done by even a small (invisible) tear in the filter.  For every one lire of fuel your engine consumes, at a conventional air:fuel mixture of 15:1 it sucks in 15 kilos of air.  In dusty conditions, that is a lot of particulate material.

ENGINE OIL:  Even if your air filter is of the highest quality and in good condition, it is not perfect.  Some very fine particles will still get through.  These should be so small that they do no immediate damage and are burned off in the combustion process.

That burning off process might stop the dirt acting like grains of sandpaper, but it leaves a residue which pollutes the engine oil and reduces lubrication efficiency.  In very dusty conditions, engine oil should therefore be changed more often.  Twice as often.

GREASED PARTS: Grease not only prevents squeaks and rust; it reduces wear between moving parts...if it is clean.   But grease and dirt mixed together act like grinding paste, scouring the parts the grease is supposed to protect,  so it is important to completely pump out or wipe away old grease and replenish with new as a regular service item.

All mechanical joints under severe load or moving at high speed used to have grease nipples (the correct service technique on these is to keep pumping clean grease into them to force out all the old grease).  Most of these joints are now "sealed for life" units, with rubber sleeves to keep the dirt out and the grease in. 

In rough and dusty condition, it is important to check these rubber envelopes (called "boots") regularly, to ensure there are no cuts and cracks in them.  Damaged boots must be replaced without delay, or major and expensive parts of the car will be quickly destroyed beyond repair.

In addition to grease nipples and "sealed" joints, there are numerous other grease points on every car - the hinges and latches on doors, bonnet and boot; window-winding ratchets and runners, handbrake ratchet, the linkages on pedal levers, seat adjustment slides, etc etc. 

In dusty conditions it is particularly important to wipe these clean and replenish with fresh grease on a regular basis.  Everything will work better and last longer.

PAINTWORK:  Dust, per se, does no harm to paintwork.  The damage is done if that dust is wiped away without sufficient water.  Dust should be flushed off the paint with copious quantities of water before wiping, and the first wiping phase should also involve plenty of water to prevent the particles of dust acting like sandpaper, creating minute scratches that will dull the finish.

Remember, too, that road "grime" contains a lot more than just earthy dust.  It contains rubber and oil and all sorts of other sticky substances that, if left too long, can stain the paintwork.

BODY TRAPS:  Any part of a car where the metal panels are folded over, creating a "pocket" or "double-skin" effect, is a potential dust-trap.  Never mind; the dust is very welcome to the space (until you hit a bump, and the dust billows all over the place, making everything filthy).

To prevent this, it is a good idea to use high-pressure air and vacuum cleaning to regularly remove dust from body traps - especially just before the rains! 

TRIM:  The sixth main way dust damages a car is by getting inside it - into the seat fabric and carpets.  It does no direct harm, and for appearances sake and to prevent the occupants' clothes being dirtied, it is quite easily and commonly swept out.

However, sweeping does not remove embedded dust and, if left, it will sooner or later become damped and either stain, discolour, or generally degrade the appearance of seats, door trim, carpets etc.

The interior trim should be vacuumed,  thoroughly and regularly, even if it doesn't actually look dirty.  Once or twice a year (and especially just before the rains) it should also be "shampooed" with a foam cleaner, to keep it looking bright and new.

Apart from its direct impact on motor vehicles, dust also has two other big effects - on driving techniques on very dusty roads and on people who walk or live next to dusty roads (see Driving Tip section).

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