GM Cutlass RWD 1970-1987 Repair Guide

Glow Plugs


There are two types of glow plugs used on General Motors Corp. diesels; the "fast glow" type and the "slow glow" type. The fast glow type use pulsing current applied to 6 volt glow plugs while the slow glow type use continuous current applied to 12 volt glow plugs.

An easy way to tell the plugs apart is that the fast flow (6 volt) plugs have a 5 / 16 in. wide electrical connector plug while the slow flow (12 volt) connector plug is 1 / 4 in. wide. Do not attempt to interchange any parts of these two glow plug systems.


A burned out glow plug tip may bulge and then break off and drop into the pre-chamber when the glow plug is removed. If this occurs, the cylinder head must be removed, remove the pre-chamber and remove the broken tip.

  1. Disconnect the negative (-) battery cable and glow plug electrical connector.
  3. Turn the plug out of the cylinder head slowly.
  5. Coat the new plug with anti-seize compound for electrical components.
  7. Torque the plug to 12 ft. lbs. (16 Nm) and connect the electrical connector.