Vacuum Pump: Description and Operation

Some models equipped with the V8-350 diesel engine are use a gear driven vacuum pump. This pump is used to operate the EGR system, heater and A/C system, as well as the transmission modulator and/or cruise control as equipped.
The pump is a diaphragm pump that requires no periodic maintenance. This pump is driven by a cam inside the drive assembly on which the pump is mounted. The drive housing assembly includes a gear on the lower end that meshes with the camshaft gear in the engine. This gear causes the cam in the drive housing to turn. The gear also operates the engine oil lubricating pump.