These plugs are "Instant-Heat" and are STILL GLOWING even after 10 second after shut off. Your engine will start definately better for a long long run.
The engine glow plugs are used to heat air entering the combustion chamber. Heating the air results in improved cold temperature starting and engine warm-up. A total of eight glow plugs are used; one for each cylinder. Each glow plug is threaded into a cylinder head port located just below the injector nozzle. The tip of each plug extends into a pre-chamber which concentrates the fuel/air mixture prior to combustion.
The glow plugs are operated by a controller/relay mounted on the rocker cover or intake manifold. The relay is in circuit with the ignition switch and is energized only when the switch is in the Start and Run positions. Turning the ignition switch to Start position allows current to flow through the switch to the controller. Once energized the controller allows current to flow through the relay and to the individual glow plugs.
If you start it up and it blows black smoke and then quits it's probably some bad plugs or the glow plug controller.
Please NOTE that Wellman Automotive has become Diesel Rx! That is why they are now boxed in Diesel Rx Boxes