Truck Repair: 99 F250 Powerstroke Hard To Start When Cold, valve cover gasket, glow plugs

Question
When the temperature is 35 degrees or below, my powerstroke diesel cranks over fine but won't start. When the temperature warms up I have no problem starting, is this a glow plug, harness, or relay issue? What do you check first?

Answer
The 99 PS glow plugs are pretty good and rarley go bad.  The first thing I would check is the relay.  If the relay tests fine, check the plugins at the valve cover for melting, when you unhook the connection at the valve cover gasket, look at the outer pins; if they show signs of melting the plastic, then you have issues under the valve cover.  Let me know if you need any further help. MIKE