Bought a 05 excursion 6.0 diesel. What was told to take some precautions in starting it, because it may have oil in the cylinders. Removed the glow plugs turned the engine over once waited a minute and turned it over again. Went into the house to get the new plugs to install and thought I'd turn it over again make sure cylinders purged before placing new plugs. This time no go, no click, however it could be the battery, I only had one hooked up. Could I have shorted something out? Also is it nessessary to replace the cracked glow plug wire cover just above the glow plug cap/cork?