Since the air crossover and intake manifold in a diesel engine is unrestricted (unlike a gasoline engine which has throttle plates creating a venturi effect) there is no vacuum source. To provide vacuum, a vacuum pump is mounted in the location occupied by the distributor in a gasoline engine. This pump supplies the air conditioning servos, the cruise control servos, and the transmission vacuum modulator where required.
The pump is a diaphragm type which needs no maintenance. It is driven by a drive gear on its lower end which meshes with gear teeth on the end of the engine's camshaft.
REMOVAL & INSTALLATION
- Disconnect the batteries.
- Remove the air cleaner, and cover the intake manifold.
- Remove the vacuum pump clamp, disconnect the vacuum line and remove the pump.
- Install a new gasket. Install the pump and reverse the removal procedures for installation.