See Figure 1
The glow plugs provide a means of ignition during starting and perform the same function as normal spark plugs, although they do so in a different manner.
The light on the dashboard which indicates when the glow plugs are hot enough to fire can also serve as a troubleshooting aid. If the light does not glow, it usually indicates a faulty plug.
- Test the plugs by having an assistant hold the starting knob in the preheat position while shorting the plugs to ground, in turn, with a screwdriver. Each plug should produce a spark if working properly. While bridging the connections, the light on the dashboard should light.
- If, after disconnecting the ground lead of the preheating system, the light still stays lit, a short circuit in the system is indicated. This is usually caused by a carbon-fouled plug electrode or by a lead touching the cylinder head. Check the leads first.
- If they seem O.K., pull the knob to the preheat position and disconnect one plug power lead at a time, starting from the ground end, until the light goes out, indicating the faulty plug.
- Glow plugs can be cleaned, but it is better to replace them if they are badly fouled.
REMOVAL & INSTALLATION
See Figures 2 through 6
- Loosen the cable, if this has not been done already, by removing the knurled nut.
- Unscrew the other nuts and remove the insulators and the bus bars.
- Using a 21 mm. socket, unscrew and remove the glow plugs.
- Before installing new plugs, clean the ducts and prechamber bores with a stiff bristle brush or a small scraper. The ball pin in the prechamber is easy to break, so don't go much deeper than 2 in. into the plug hole.
- Crank the engine a few times to blow out any carbon particles loosened by the scraping, then insert the plugs. Do not exceed 35 ft lbs torque.
- It might be a good idea to recheck these new plugs to ensure that all connections are tight and not grounded and that the plugs are not faulty.