Self appointed experts are increasingly appearing on the (private) TV channels. We don't mean the car-doctors, who generally produce pretty good work, but the fast young men (and women), who take a look at the car from the outside, go for a short test-run, then tell you exactly what's wrong with it. Mostly, they have one or two defects, typical for this vehicle handy and at least they do consider a look underneath the car as a must, although only with a torch and generally without, e.g., even a tyre lever.

As long as it concerns fairly new vehicles with not too much mileage on the clock, this may be ok, but with older cars, this is by far, just not enough. Indeed, laymen tend to rely quite happily on this type of 'expert opinion' and possibly, flush a great deal of money down the drain. Even if the price is afterwards haggled down, the remedying of internal corrosion e.g., causes substantially higher costs. The only, and not quite legal way out, is to find a similarly stupid buyer, for whom the optical impression is all that matters.

What one actually needs, is X-ray vision or the capability to send one's eyes into the hollow profiles. In the medical world this has been around for a long time, in the meantime, it has been thus perfected, so that one can examine the stomach for ulcers, right up to the intestine. Admittedly, the flexible tube is not the thinnest and sometimes causing gagging. For the motor mechanic a very much thinner and more flexible fibre-glass cable, with an optical lens is available. The times of rigid endoscopes (see figure 3), which had an outside casing-sheath holding a fibre-optical guide, a cable approach and a lens with a deflection prism and a distance spacer, are a thing of the past (see figure 4).

To inspect larger spaces, one had to work with a so-called 'adjustable-prism endoscope', which is a rigid instrument with a prism at the end which gave an unchangeable 90° angle of view. Not much was achieved by pushing this down the 10-millimetre spark plug hole. Added to this, was the price, about DM 1200. What a difference to the modern, flexible endoscope of today. It transfers the pictures through bundled fibre-glass cables. One can look forwards in any direction and also has a limited view to the rear, e.g., of the valves. It enables the inspection of far more areas in the most varying machines, equipment or engines even if there is no direct access. Light, e.g., from halogen lamps, can be externally generated and can be guided to the inside. A further application to be considered, is e.g., the clutch, if it doesn't happen to lie in an oil-bath.

The most advanced and at the same time, the highest quality sub-group of the flexible endoscopes, are the so-called video-endoscopes. They can, depending on the manufacturer, have various names, such as Videoscope. Video-endoscopes use the newest digital technology to generate and transmit pictures. A CCD- or CMOS chip is mounted directly in the lens. This chip creates the digital picture of the area to be examined, and transmits it to the other components in the endoscope. More precisely, this can be a processor, which assimilates the received data before sending it to a monitor or saving it to a connected hard-disc. Apart from this, video-endoscopes can, depending on their features, produce the pictures as stills or as video-clips. Using this possibility, the operator can afterwards optimise the pictures or measure an object.

The application areas of the endoscopes seems, at the moment, to be limitless. You may have seen these video-clips, which show the combustion process inside the combustion chamber. Images like these can come from an endoscope, indeed, it must have a rigid optical light-conducter for the transmitting of the colour images. Of course, this may not penetrate the intensely hot combustion zone. It is protected by special glass, which should however, also even be suitable for Diesel engines running at full power. The illumination is provided through a second hole, drilled straight through the cylinder head from the other side.

In the event that you're looking for a practice orientated example: Compensating shafts are often driven by chains. Should they be installed in the crankshaft area or even beneath it, one can check whether the're functioning correctly by lowering the endoscope's camera in through the chain-shaft. 01/14