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.
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