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Vacuum Tank

A term used for vacuum canister, vacuum chamber, or vacuum reserve tank.

Vacuum Tap

A point at which a vacuum can be released from an enclosure.

Vacuum Test

A test to determine the presence of a vacuum.

Vacuum Testing

A test on the intake manifold pressure to determine the condition of the pistion rings, valves, ignition timing and valve timing or to test for a restricted exhaust system.

Vacuum-Advance Control

An emissions-control system component that allows vacuum advance only during certain modes of engine operation.

Vacuum-Advance Solenoid

An electrically operated two-position valve that provides or prevents a vacuum signal to the distributor vacuum-advance unit.

Vacuum-Check Valve

1. An air-operated mechanical device that closes a vacuum line to the vacuum reserve tank whenever the manifold vacuum pressure falls below the reserve vacuum pressure. 2. In a power-brake system, a one-way valve on the power cylinder vacuum-supply lose connection to maintain system vacuum under certain conditions.

Vacuum-Suspended Power Brake

A type of power brake in which both sides of the piston are subjects to a vacuum.

VAD

Vacuum advance delay.

VAF

Vane air flow.

VAG-COM

A laptop based scantool for VolksWagon and Audi Group vehicles. A ROSS-TECH product downloadable from www.ross-tech.com.

Valence Bond

The extent to which an atom combines or "bonds" with other atoms.

Valence Electron

The electron in the outermost shell or orbit of an atom.

Valence Ring

The outermost orbital path of electrons around the nucleus of the atom.

Valence Shell

The outermost shell or orbital path of an atom.

Validity List

A list of valid bulletins supplied by the manufacturer.

Valleys

The annular grooves or recessed areas between the lands of a valve spool.

Value Guides

A used-car price guide.

Valve

A circular-stemmed device used to control the flow or air/fuel mixture in and the flow of burned gasses out of the engine.

Valve Angle

The angle at which the valve face is machined.