It’s not just government departments that leak.

MOTOR INDUSTRY TECHTALK ARTICLE

Mention fault diagnosis to almost anyone concerned with vehicle engineering, and their mind flies instantly to advanced electronics.

Manufacturers of cars and commercial vehicles alike require their distributors to be equipped with computer equipment and software capable of diagnosing engine computer management, electrical and other malfunctions, and to have their staff trained in its use. Few manufacturer-scrutinised workshops nowadays wish to acknowledge to their customers the importance of the grey-haired guy in the corner with sharp ears, a box of tools and an oily rag. It is just not the image.

However, the truth, as anyone in the trade will acknowledge, is that practical experience still counts in a big way. This is particularly true when the problem is not in the engine department, the electrics or one of those cunning intelligent transmission systems that do everything except tell you what they plan to do next. Know-how is everything if a workshop is to be efficient, profitable and a source of relief and pleasure to customers rather than of frustration and expense.

How many leaks?

Ask anyone with experience of vehicle maintenance, and they will tell you that the two causes of the greatest customer frustration and dissatisfaction are intermittent faults and leaks. Many of the intermittent faults are, nowadays, capable of being detected by those electronic diagnostic systems, but nobody has yet come up with a computer that can tell you exactly where the source of a leak is, whether of oil, coolant, air-conditioning refrigerant or rainwater. Finding leaks is down to the experience and ingenuity of the guys out at the back.

The snag is that, if they use hit or miss traditional methods, they are likely to find the largest leak, or even the largest two. However, they may well not spot smaller leaks, which will become apparent only when the bigger leaks have been cured and the furious customer is on a ferry to Belgium. Most (although, surprisingly, not all) workshops have therefore recognised that UV fluorescent leak detection systems, pioneered some seventeen years ago by Primalec in Kent, are the answer. UV leak detection provides the best method of ensuring that all the leaks have been found, and that customers do not self-combust on the way home (or on the way to Belgium).

To track down the leaks, an appropriate UV fluorescent fluid is added to the system in question (not brakes, it should be noted) and the engine, aircon system or whichever system is suffering leakage is run or pressurised so that fluid will emerge from whatever leaks are present. Shining a UV lamp all around possible leakage points then quickly reveals all the leaks because they glow brightly where the UV light encounters the fluorescent additive. OK, you knew that. Many people in the trade in 2004 do. However, bear in mind the word ‘brightly’. Brightness depends on the concentration of the leak detection agent in the carrier fluid – oil or whatever.

Look out for the catch

The problem is that, since Primalec originated this UV leak detection technique back in the eighties, the supply of UV leak detection fluids has become a seriously competitive business. In an effort to achieve the lowest price, or possibly because of a lack of technical expertise, some suppliers offer UV leak detection materials of much lower concentration than those of the market leaders (in some cases diluted beyond the point of real effectiveness). The result is that, when this diluted fluid is used in the same quantities as the original materials, the visibility of the fluorescent glow, even from large leaks, is much reduced. Very small leaks are likely not to be spotted at all, simply because the fluorescence is not sufficiently visible in the ambient light of the workshop. This problem has been particularly prevalent with air-conditioning leak-tracing fluids.

Of course, it is true that, if a much larger quantity of the dilute fluid is used, the result is once again bright enough to be effective. However, using larger quantities will increase the price per application dramatically, thereby eliminating the apparent price advantage of the cheaper fluid. In some cases, it will actually prove to be more expensive.

Other sources of hidden cost in the use of UV leak detection lie in using the wrong concentration for the job in hand, and in the method of application. As an example, Primalec has developed three main types of its Glo-Leak UV leak detection fluids to provide optimum efficiency in various applications. Glo-Leak GL310 is for engine, transmission and hydraulic oils, and for fuel leaks. GL390 is for radiators and cooling systems, GL396 is for bodywork. Use the right material for the job, and costs are minimised, efficiency is maximised.

In the case of air-conditioning systems, Primalec produces Glo-Leak for A/C in three standard strengths, giving you a choice of injection methods and dosage rates from a 1.25ml micro-dose through a 2.5ml mini-dose to the 5ml standard dose. For larger commercial systems, even higher concentrations are available.

Getting it right

A number of manufacturers of commercial and specialised vehicles now incorporate Primalec’s Glo-Leak products into the oils and A/C systems of their products in the factory, and then require their service agencies to be equipped with the right UV lamps to be able to detect leaks quickly and efficiently. Most of these manufacturers are wary of admitting that they do this, understandably not wishing to suggest that they expect their vehicles to leak at some stage in their lives. But it does point the way to how car manufacturers might give car distributors’ workshops the same degree of disciplined efficiency where leak detection is concerned as they already have when diagnosing engine management system failures.

You will notice the reference above to ‘the right UV lamps’. Some lamps seem brighter than others, but may be less effective as leak detectors. This is because, to achieve the best results, the lamp must provide both the right combination of wavelengths in the light beam and the correct degree of contrast between the light beam and the fluorescence. It is quite likely that cheaper products may be poorer value for money than those of specialist brands, such as Invictalux, Primalec or Vector.

Air conditioning is where it’s at

All this technology is only useful if it is saving time and generating profits. While there is and will probably always be a continuing need for cost-effective leak detection of oils and coolants, the growth in leak detection work for the garage trade is undoubtedly in the maintenance of air-conditioning systems. There has been a dramatic increase in the number of air-conditioned vehicles on the road over the last two or three years, and effective, fast A/C leak detection is becoming a key factor in generating profits from air-conditioning servicing work. But there are other factors too. Like achieving effective flushing of aircon systems. Like being able to seal all the tiny leaks in old systems at low cost without physically replacing them and like eliminating small leaks in the rubber parts of car air conditioners by rejuvenating the flexible components which tend to degrade during the winter.

Then there’s economically converting vehicle air conditioning systems from R12 to R134a without flushing, opening the systems or changing major components. It’s all possible, and profitable, if you have the know-how and the right materials. If you want to learn about this, you could do worse than do what I did, which was to go to www.primalec.co.uk and browse.