A small nipple valve that allows connection of a pipe and is operated by loosening.

A defect in which pigment from a lower coat of paint diffuses into an upper coat and discolours the latter. A non-bleeding colour is one that is not soluble in materials used over it and consequently does not work up into succeeding layers. Body filler may also cause bleeding if an excessive amount of hardener is added.

Repainting of panels or parts of panels and fading out the new colour onto adjacent prepared panel work to render the repair invisible. Normally only carried out on basecoat-and- clear finishes, as it is very difficult to blend a direct gloss paint finish.

Flaps used to mix hot/cold and fresh/recirculated air in a heater system.

Description of a 'quick press' of the throttle to make the engine rev up.

The development of hollow bubbles or water droplets in a paint film. Blistering is usually caused by the expansion of air or moisture trapped beneath the film. It can occur rapidly or any time after application as the paint film ages. Blistering may also occur from the presence of unreacted acid within the paint film.

A diagram of a system, in which the main parts or functions are represented by blocks connected by lines, which show the relationships between the blocks.

General term used to describe a bar that prevents an action of some kind.

A powder-like deposit which sometimes forms on the surface of a paint. It is often the result of a solvent component partly dissolving the pigment(s) and then depositing them on the surface when the temperature is below the 'dew point',( i.e. the temperature at which moisture will condense on the surface)

Ignition of fuel in the inlet manifold causing a flame to rise out of the air intake through the carburettor.