!always! put either something under the glow plugs or have a magent with a string on hand and be working over concrete, because the da#$ little nuts that hold the electrical leads onto the glow plugs have a tendency to fly off down into the black hole between your injection pump and engine block. I had to go to Home Depot to buy new ones...they had none of that size except ones which lock (have soft plastic strip after threads). I guess I'll have a good time putting in new ones eventually... Also, if one of those falls in the grass, you're done, because they blend right in with the dirt. It's funny how the simplest jobs always wind up taking the longest.