From Khartoum to Cape Town/AFRICAN JOURNEY. How the glamour of a trans-Africa trek by Land Rover can begin to wear thin

YOU do know how to repair cars, don't you?'' the Australian expatriate painter asked, wiping his hands with an oily rag. A weathered Land Rover, scratched, battered, and with a roomy canvas tent affixed to one side, stood parked beneath the baobab trees overlooking the Indian Ocean. ``I mean, you wouldn't go knocking around Africa without knowing some of the basics, would you?''

I wasn't going to tell him that I barely knew where the fuel pump was located or that my sole source of mechanical know-how was a do-it-yourself manual. The fact was, my vehicle had mysteriously conked out and there was no way I could start it up again. For one embarked on a ``trek'' across Africa the problem was more than a little disconcerting.

The Australian, who lived, traveled, and painted out of his car, gave my Land Rover a quick once-over. The problem was simple enough, he concluded. No gas. I had accidentally switched from the main fuel tank to one of the empty reserve tanks.

Embarrassing as it was, the incident did bring home the urgent need for boning up on car repair methods, particularly for someone used to the convenience of airplanes, rental cars, horse caravans, or one's own legs when reporting in the third world. Mechanics are few and far between in the middle of the Somali outback or the Kalahari Desert. Maneaters of Tsavo

As it happened, less than a week later, I did break down in the wilds of Tsavo National Park about 100 miles southeast of Nairobi. Recalling tales of the Maneaters of Tsavo -- lions which plagued construction of the Mombasa-Uganda railway at the turn of the century -- I struggled to fix a faulty fuel line while my companion scanned the surrounding savannah for predators. It was with no uncertain relief that I saw a group of park maintenance men, casually clinging to the back of a tractor, rolling up to help me.

Traveling in one's own vehicle is undoubtedly one of the most exciting ways of roaming the continent. Apart from the personal freedom of movement, one can penetrate areas otherwise inaccessible and meet people more easily. Recently, driving along the coast road south of Mombasa, I picked up a hitchhiker.

``What tribe are you from?'' he asked.

Somewhat taken aback, I said ``American.''

He nodded thoughtfully. ``That's a very big tribe, isn't it?''

Breakdowns, however, are but one of many impediments that can make overland expeditions in Africa a hazardous or at least thoroughly complicated venture. With so many facilities taken for granted in the United States or Europe, one can hardly imagine some of the drawbacks that seem specifically designed to frustrate even the most patient and determined traveler. Insurance pitfalls

This network of obstacles is illustrative, perhaps, of the lack of unity or economic cooperation throughout much of Africa. For example, it is virtually impossible to obtain a single automobile insurance policy which gives coverage everywhere in the continent. The only option is to purchase new coverage at each border post and hope for the best.

``Apart from Kenya and a few other countries, you'll find the insurance pretty useless,'' said Benny Jorgensen, a Danish company manager based in Uganda. ``Should anything happen, you'll be lucky if they reimburse you. And even if they do, it is usually in a worthless, inconvertible currency.''

The romantic notion of driving from Africa's north to its south is further tarnished by raw political realities: Civil wars, bandits, spy paranoia, road permits, border controls, corruption. A surprising number of countries require special travel documents for certain ``security'' areas, or forbid visitors outright.

Even the most innocuous of activities -- photographing the parliament buildings in downtown Nairobi -- can suddenly turn dangerous when security men appear to grab your camera.

As a traveler in Kenya will quickly discover, personal security and protection against theft are overriding concerns, if not obsessions, among many residents. Not only in Nairobi, but in the countryside, too. Daily newspapers are peppered with stories of murders, muggings by ``panga'' (machete) gangs, and burglaries. Just how tense feelings are is suggested by the extremely violent, impromptu form of mob justice meted out to those who are caught. Urban violence

Over the past few years, the Kenya government has been trying to crack down on urban violence, a difficult task considering the high rate of unemployment, particularly among the young who have left school.

The arrival of 15,000 women in Nairobi for the world conference on the United Nations Decade for Women and the consequent potential for bad international publicity, seems to be what it takes to get authorities to dragnet streets and suburbs in a bid to keep the city safe at least for the duration of the gathering.

While some observers insist that crime is not as bad as is often made out, others maintain that it is getting steadily worse. ``I can guarantee that you will be robbed at least once before you leave Kenya,'' blithely remarked the English shipping director whose company was handling my vehicle. ``In fact, there is a pretty good chance that your vehicle will have been plundered before you even receive it.''

Sure enough, despite padlocked trunks, various pieces of equipment -- a shortwave radio, jerry cans, clothes, and rock tapes -- had already been removed from the vehicle by the time it had passed through customs in Mombasa. The thieves proved to be quite discriminating. Camping gear, boots, and classical music tapes did not interest them.

What can be done to minimize the risks? ``Well you see, I have a distinct advantage over you. I'm fat,'' continued the enormous Englishman. ``Africans respect big people. It's a sign of power. They'll think twice about tackling you.

``All I can say is assume that everything you've got in your vehicle is up for grabs and take whatever precautions you can. Car break-ins are a fact of life in this country.''

Once back in Nairobi, I had firm wire mesh fitted over the rear windows, strongboxes bolted into the back, and extra locks attached to anything that moved.

Following crime, one of the most nerve-wracking gauntlets facing overland travelers are Kenya's lethal driving habits, far worse than what I have seen in Pakistan or India. One Kenya guidebook recommends ``evasive'' rather than ``defensive'' driving as a way to survive the country's roads.

Drunk driving is an acute problem, but so are the favorite pastimes of overtaking on blind curves, dangerously overloading trucks, hogging the center of the road, and keeping headlights switched off to save on bulbs until the sheer darkness mandates their use.

The worst offenders, however, are the matatus, jampacked minibuses whose name can be loosely translated as ``always room for three more.'' Hurtling down the highways, their main ambition seems to be to take on as many passengers as possible while reaching a destination in the shortest time possible.

On several occasions I have watched foreigners intent on savoring some local color, climb out of matatus with blanched, ``never again'' expressions on their faces.

Recently, Kenyan President Daniel Arap Moi announced his intention to ``declare war'' on speeding matatus. But one wonders what can really be done about their drivers who pilot the vehicles with an abandon suggesting immunity to the normal considerations of personal safety.

Police have been ordered to haul in offenders and there are plans to introduce stricter driving regulations. And in an effort to educate the young, authorities recently opened a youth traffic center in Nairobi where school children can ride around on bikes and learn the highway code under simulated road conditions.

In the meantime I ponder the relative security of my Land Rover beset as it is by an internal propensity to break down at awkward moments and an external vulnerability to the reckless driver or the acquisitive thief.