GM Full-Size Trucks 1970-1979 Repair Guide

Vacuum Pump

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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



  1. Disconnect the batteries.
  2.  
  3. Remove the air cleaner, and cover the intake manifold.
  4.  
  5. Remove the vacuum pump clamp, disconnect the vacuum line and remove the pump.
  6.  
  7. Install a new gasket. Install the pump and reverse the removal procedures for installation.
  8.  

 
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