In vehicles, diesel vacuum pumps are used when the intake manifold cannot generate the required vacuum, such as direct injection or turbo engines with variable valve time. The vacuum pump creates a negative air pressure between 750 mbar and 850mbar (10-12 psi), by removing the air from the vacuum system.

There are two main types of vacuum pumps for engines: electric and mechanical.

1. Mechanical Vacuum pump: This type is driven by the engine camshaft or accessory drive. The vacuum is created by a rotating piston or vane mechanism that draws air from the intake manifold of the engine. Many older vehicles, as well as some performance engines, have mechanical vacuum pumps.
2. Electric vacuum pump: Many modern vehicles, particularly those with turbocharged or diesel engines, use electric vacuum pumps. These pumps are usually separate units powered by the vehicle’s electrical system. Electric motors are used to drive a diaphragm pump or rotary one. Mechanical vacuum pumps are bulkier and less versatile than electric ones.

The type of vacuum pumps used in engines can vary depending on their manufacturer and design.